阅读说明：本技术 一种利用nad(p)-依赖型醇脱氢酶催化生产d-阿洛酮糖的方法 (Method for producing D-psicose by using NAD (P) -dependent alcohol dehydrogenase as catalyst ) 是由 林建强 温鑫 宋欣 任一林 林建群 于 2020-12-29 设计创作，主要内容包括：本发明公开了一种利用NAD(P)-依赖型醇脱氢酶催化生产D-阿洛酮糖的方法,包括以下步骤：对NAD(P)-依赖型醇脱氢酶基因adh进行优化合成,构建重组质粒pET22b-adh,构建重组菌株,重组菌株在低温下诱导培养,得到粗酶液,分离纯化粗酶液并经超滤浓缩后得到纯酶液,利用粗酶液或纯酶液构建反应体系催化阿洛醇溶液生产D-阿洛酮糖。本发明方法简单、条件温和、转化效率高,且是本发明首次证实NAD(P)-依赖型醇脱氢酶能够用于催化阿洛醇生产D-阿洛酮糖,因此本发明方法有利于D-阿洛酮糖的工业化生产。(The invention discloses a method for producing D-psicose by using NAD (P) -dependent alcohol dehydrogenase catalysis, which comprises the following steps: for NAD (P) -dependent alcohol dehydrogenase gene adh Optimized synthesis is carried out to construct a recombinant plasmid pET22b- adh Constructing a recombinant strain, carrying out induction culture on the recombinant strain at low temperature to obtain a crude enzyme solution, separating and purifying the crude enzyme solution, carrying out ultrafiltration concentration to obtain a pure enzyme solution, and constructing a reaction system by using the crude enzyme solution or the pure enzyme solution to catalyze the arabitol solution to produce the D-psicose. The method is simple, mild in condition and high in conversion efficiency, and the method proves that the NAD (P) -dependent alcohol dehydrogenase can be used for catalyzing the production of D-psicose from the allol for the first timeThe method of the invention is beneficial to the industrial production of D-psicose.)

1. A method for producing D-psicose catalyzed by NAD (P) -dependent alcohol dehydrogenase, comprising the steps of:

(1) after the NAD (P) -dependent alcohol dehydrogenase gene is amplified, the NAD (P) -dependent alcohol dehydrogenase gene is connected to a vector plasmid through double enzyme digestion to obtain a recombinant plasmid;

(2) transforming the recombinant plasmid into escherichia coli to obtain a recombinant strain;

(3) inoculating the recombinant strain into a culture medium, carrying out induction culture under a low-temperature condition, then collecting and resuspending thalli, crushing the resuspended thalli by using ultrasonic waves, and centrifugally collecting supernatant, wherein the supernatant is crude enzyme liquid;

(4) purifying the crude enzyme solution by using a separation and purification column, and performing ultrafiltration concentration to obtain a pure enzyme solution;

(5) and (3) constructing a reaction system by using the crude enzyme solution or the pure enzyme solution, and catalyzing the arabitol solution to produce the D-psicose.

2. The method for producing D-psicose by NAD (P) -dependent alcohol dehydrogenase catalysis according to claim 1, wherein the NAD (P) -dependent alcohol dehydrogenase gene in the step (1) has one of the following nucleotide sequences:

(1) a nucleotide sequence shown as SEQ ID NO. 2;

(2) has more than 95 percent of homology with the nucleotide sequence shown in SEQ ID NO.2 and codes the nucleotide sequence with the same functional amino acid sequence with the amino acid sequence shown in SEQ ID NO. 1.

3. The method for producing D-psicose catalyzed by NAD (P) -dependent alcohol dehydrogenase as claimed in claim 1, wherein the primer pair amplified in step (1) is:

adh-pET22b-Nde I-U：5’-GGGAATTCCATATGGCCCAGGCCCTGGTGCTG GAAAAG-3’；

adh-pET22b-Xho I-D：5’-CCGCTCGAGCAGAACAATCTGCAGTTTAACA TC-3’。

4. the method for producing D-psicose catalyzed by NAD (P) -dependent alcohol dehydrogenase as claimed in claim 1, wherein the inducing culture in step (3) is performed under the following conditions: inoculating the recombinant strain into LBG medium containing antibiotics, and shake culturing to OD₆₀₀IPTG was added at 0.8 and then the temperature was lowered to continue induction culture.

5. The method for producing D-psicose catalyzed by NAD (P) -dependent alcohol dehydrogenase as claimed in claim 4, wherein the ultrasonication in step (3) is performed under the following conditions: and after the induction culture is finished, resuspending the thalli collected by the bacterial liquid through low-temperature centrifugation, then carrying out ultrasonic crushing on the resuspended bacterial liquid until the bacterial liquid is transparent, and collecting supernatant through low-temperature centrifugation, wherein the supernatant is the crude enzyme liquid.

6. The method for producing D-psicose catalyzed by NAD (P) -dependent alcohol dehydrogenase according to claim 1, wherein the purification step in the step (4) is: and (3) passing the crude enzyme solution through a nickel column, and then leaching by using a buffer solution containing imidazole to obtain a leaching solution, namely a pure enzyme solution.

7. The method for producing D-psicose by NAD (P) -dependent alcohol dehydrogenase catalysis according to claim 1, wherein the reaction system in the step (5) comprises 70% by volume of Na₂HPO₄-NaH₂PO₄Buffer, 10% alcolol solution, 10% NAD⁺Solution and 10% pure enzyme solution or crude enzyme solution.

8. The method for producing D-psicose by using NAD (P) -dependent alcohol dehydrogenase as claimed in claim 1, wherein the reaction system in step (5) comprises 10% by volume of the solution of the psicose and 90% by volume of the crude enzyme solution.

9. The method for producing D-psicose catalyzed by NAD (P) -dependent alcohol dehydrogenase as claimed in claim 7 or 8, wherein the concentration of the solution of the said psicose is 500 mM.

10. The method for producing D-psicose catalyzed by NAD (P) -dependent alcohol dehydrogenase according to claim 1, wherein the catalysis conditions in the step (5) are as follows: and uniformly mixing the solution in the reaction system, and then placing the mixture in a 50 ℃ shaking table for reaction for 4 hours to obtain the D-psicose.

Technical Field

The invention belongs to the technical field of rare sugar biotransformation, and particularly relates to a method for producing D-psicose by catalysis of NAD (P) -dependent alcohol dehydrogenase).

Background

The International Society for Rare Sugars (ISRS) defines Rare Sugars as a class of monosaccharides and their derivatives that occur in nature but in very small amounts. The rare sugar has the characteristics of low calorie, low absorption and the like, has various physiological functions, and plays an important role in the fields of diet, health care, medicine and the like.

D-psicose is a C-3 position epimer of D-fructose, is a rare sugar with ultralow calorie, has the sweetness of 70 percent of that of cane sugar, and is hardly absorbed by the digestive tract, so the D-psicose can be an ideal cane sugar substitute sweetener beneficial to losing weight. In addition, the D-psicose also has the effects of reducing blood sugar, resisting oxidation, protecting nerves, treating cardiovascular diseases and the like. D-psicose is also approved by the U.S. Food and Drug Administration (FDA) as "generally recognized as safe" (GRAS) number 400, allowing use as an ingredient in foods and dietary supplements.

Currently, D-psicose is produced mainly by means of biotransformation. D-psicose 3-epimerase (DPE), D-tagatose 3-epimerase (DTE) or L-ribulose 3-epimerase (LRE) were reported to catalyze D-fructose to D-psicose. Wherein, the D-psicose 3-epimerase has higher substrate specificity to D-psicose, and has important research value. However, the production of D-psicose by using epimerase to catalyze D-fructose is restricted by thermodynamic equilibrium, resulting in low conversion rate and poor production capacity of D-psicose. In addition, the strainBacillus pallidusY25 andEnterobacter aerogenesthe resting cell reaction of IK7 can realize the direct production of D-psicose from the aloitol, but the microbial transformation method for preparing the D-psicose does not relate to the thermodynamic equilibrium problem, and the process steps are simple, but the microorganisms existThe problems of long production period, different reaction conditions, complex product extraction process and the like also cause higher total cost, and are not suitable for industrial production.

The enzyme catalysis conversion method has the advantages of mild catalysis reaction conditions, high conversion rate, easy product separation and the like, but no patent and report about the production of D-psicose by catalyzing the allol with any enzyme are available at present.

Disclosure of Invention

In order to solve the technical problems, the invention aims to provide a method for producing D-psicose by using NAD (P) -dependent alcohol dehydrogenase catalysis, which converts the psicose into the D-psicose by the enzyme catalysis, has simple operation and low cost, and can realize the large-scale production of the D-psicose.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a method for producing D-psicose by using NAD (P) -dependent alcohol dehydrogenase catalysis, which comprises the following steps:

(1) recombinant plasmid pET22b-adhThe construction of (1): synthesis of His-tag-free recombinant plasmid pETDuet from NAD (P) -dependent alcohol dehydrogenase Gene_-1-adhAnd using this as a template and a primer pairadh-pET22b-Nde I-U：5’-GGGAATTCCATATGGCCCAGGCCCTGGTGCTGGAAAAG-3’；adh-pET22b-Xho I-D: 5'-CCGCTCGAGCAGAACAATCTGCAGTTTAACATC-3' is the target gene obtained by PCR amplification of upstream and downstream primersadhFragments, products recovered by restriction enzyme NdeIAnd Xho ICarrying out double enzyme digestion on plasmid pET22b and PCR amplification products respectively, and recycling the double enzyme digestion products and then utilizing T₄The ligase is used for ligation to obtain a recombinant plasmid pET22b-adh；

(2) Construction of recombinant strains: the recombinant plasmid pET22b-adhTransferring the cells into expression competent cells by a heat shock transformation method, recovering the cells on an LB liquid culture medium, coating the recovered cells on an LB solid plate containing ampicillin resistance, and standing and culturing the cells overnight; selecting a single colony, transferring the single colony to an LB culture medium added with ampicillin, and continuously culturing to obtain a recombinant strain;

(3) preparation of crude enzyme solution: inoculating the recombinant strain to LBG medium containing Amp according to the inoculation amount of 1%, and performing shake culture at 37 ℃ until OD is achieved₆₀₀Adding IPTG at 0.8, then reducing the temperature to 20 ℃, and continuing induction culture; after the culture is finished, centrifuging the bacterial liquid at low temperature, collecting thalli, then resuspending, carrying out ultrasonic crushing on the resuspended bacterial liquid by using an ultrasonic crusher, setting the amplitude to be 60, crushing for 5 s, stopping for 10 s until the bacterial liquid is transparent, centrifuging at low temperature, and collecting supernatant, wherein the supernatant is crude enzyme liquid;

(4) preparation of pure enzyme solution: selecting a nickel column as a separation and purification column, passing the crude enzyme solution through the nickel column, firstly washing the nickel column by using a Binding Buffer, then leaching the protein by using an precipitation Buffer, and concentrating and purifying the obtained leaching solution by using a 10 kDa ultrafiltration tube until the protein concentration is 20 mg/ml to obtain a pure enzyme solution;

(5) preparation of D-psicose: mixing 10% pure enzyme solution or crude enzyme solution with 70% 20mM Na₂HPO₄-NaH₂PO₄Buffer, 10% 500 mM Arolol solution, 10% 20mM NAD⁺The solution forms a reaction system, the solution in the reaction system is uniformly mixed and then placed at 50 ℃ for shaking table reaction for 4 h to obtain the D-psicose.

Further, the NAD (P) -dependent alcohol dehydrogenase is derived fromGluconobacter frateurii。

Further, the NAD (P) -dependent alcohol dehydrogenase gene is synthesized by codon-optimizing an original sequence according to an amino acid sequence of NAD (P) -dependent alcohol dehydrogenase in accordance with a codon analysis table for Escherichia coli.

Further, the NAD (P) -dependent alcohol dehydrogenase gene has one of the following nucleotide sequences:

(1) a nucleotide sequence shown as SEQ ID NO. 2;

(2) has more than 95 percent of homology with the nucleotide sequence shown in SEQ ID NO.2 and codes the nucleotide sequence with the same functional amino acid sequence with the amino acid sequence shown in SEQ ID NO. 1.

Further, another reaction system in the step (5) comprises 10% by volume of 500 mM allohol solution and 90% by volume of crude enzyme solution.

Further, the Binding Buffer comprises 20mM NaH₂PO₄500 mM NaCl, 30 mM imidazole, pH 7.4.

Further, the Elution Buffer comprises 20mM NaH₂PO₄500 mM NaCl, 200 mM imidazole, pH 7.4.

Further, the LBG medium includes 10 g/L peptone, 5 g/L yeast powder, 10 g/L sodium chloride and 5 g/L glucose.

Compared with the prior art, the technical scheme of the invention has the following advantages:

the invention is derived from the first utilizationGluconobacter frateuriiAs a biocatalyst, nad (p) -dependent Alcohol Dehydrogenase (ADH) catalyzes the conversion of allol to produce D-psicose. The method is simple and rapid, can produce D-psicose by using crude enzyme liquid and pure enzyme liquid, and can produce D-psicose without adding expensive coenzyme NAD +; the method has the advantages of mild reaction conditions, high conversion rate, short conversion time, few byproducts, particularly few byproducts in pure enzyme solution, and excellent conversion effect; the product obtained by the method is easy to separate and low in cost, the production method of the D-psicose is expanded, the method can be used for large-scale separation and purification of the D-psicose, and the method is suitable for industrial production of the D-psicose, so that the method has high practical application value.

Drawings

FIG. 1: recombinant plasmid pET22b-adhAnd constructing a graph.

FIG. 2: recombinant plasmid pET22b-adhColony PCR verification (a) and double enzyme digestion verification map (b); wherein M: marker; c1: with pETDuet_-1-adhPositive control PCR product as template; c2: a negative control PCR product with sterile double distilled water as a template; 1-10: by recombinant strainsE.coli DH5a-pET22b-adhSingle colony is PCR product of template; 11: nde IAnd Xho IDouble enzyme digestion products.

FIG. 3: SDS-PAGE recombinant protein analysis map; wherein M: protein marker; 1: recombinant strainE.coliBL21 star (DE3) -pET22b holoprotein; 2: recombinant strainE.coli BL21 star (DE3)-pET22b-adhA whole protein; 3: recombinant strainE.coli BL21 star (DE3)-pET22b-adhSupernatant fluid; 4: recombinant bacteriumE.coli BL21 star (DE3)-pET22b-adhAnd (4) precipitating.

FIG. 4: ADH purification diagram; wherein M: marker; 1: ADH crude enzyme solution; 2: 200 mM imidazole rinse.

FIG. 5: a liquid phase diagram of catalyzing the D-psicose with the ADH pure enzyme liquid; wherein 1: an allol standard; 2: d-psicose standard; 3: and (3) reaction liquid.

FIG. 6: in the presence of coenzyme NAD⁺The crude ADH enzyme liquid catalyzes the allol to be D-psicose in a liquid phase diagram; wherein 1: an allol standard; 2: d-psicose standard; 3: and (3) reaction liquid.

FIG. 7: without addition of coenzyme NAD⁺The crude ADH enzyme liquid catalyzes the allol to be D-psicose in a liquid phase diagram; wherein 1: an allol standard; 2: d-psicose standard; 3: reaction solution; 4: by-products.

Detailed Description

The technical solution of the present invention will be described in further detail with reference to specific examples.

Example 1

NAD (P) -dependent Alcohol Dehydrogenase (ADH) is derived fromGluconobacter frateuriiNBRC 3264 (NZ _ BEWN 01000006.1), the ID number of the enzyme is WP _099183078.1, and the amino acid sequence is shown as SEQ ID NO. 1.

NAD (P) -dependent alcohol dehydrogenase geneadhIs synthesized by codon-optimizing the original sequence according to the codon analysis table of Escherichia coli based on the amino acid sequence of NAD (P) -dependent Alcohol Dehydrogenase (ADH), and optimized NAD (P) -dependent alcohol dehydrogenase geneadhThe nucleotide sequence of (A) is shown in SEQ ID NO. 2.

A method for producing D-psicose by using NAD (P) -dependent alcohol dehydrogenase catalysis comprises the following specific steps:

one, the recombinant plasmid pET22b-adhIs constructed and verified

Recombinant plasmid pET22b-adhThe constructed spectrum is shown in FIG. 1.

1. PCR amplification of target genesadh: optimizing NAD (P) -dependent alcohol dehydrogenase geneadhHis-tag-free recombinant plasmid pETDuet synthesized by Biotech_-1-adhUsing the obtained mixture as a template and a primer pairadh-pET22b-Nde I-U: 5'-GGGAATTCCATATGGCCCAGGCCCTGGTGCTG GAAAAG-3' (SEQ ID NO. 3) andadh-pET22b-XhoI-D: 5'-CCGCTCGAGCAG AACAATCTGCAGTTTAACATC-3' (SEQ ID NO. 4) is used as the target gene for the amplification of the upstream and downstream primersadhAnd recovering the PCR amplification product.

2. Double restriction enzyme plasmid pET22b and PCR amplification productadh: using restriction enzyme NdeIAnd Xho IPlasmid pET22b and PCR amplification product were separately identifiedadhCarrying out double enzyme digestion, and recovering the double enzyme digestion product.

3. Connecting: by T₄Ligase ligates double-enzyme products pET22b andadhand obtaining the connecting liquid.

4. Construction of recombinant bacteriaE.coli DH5a-pET22b-adh: 50. mu.L of clone competent cells were takenE.coliDH5 alpha, adding 10 mu L of the above prepared connecting liquid, ice-cooling for 30 min; then hot shocking in 42 ℃ water bath for 45 s, and immediately carrying out ice bath for 2 min; then 500 mL of sterile LB liquid medium without antibiotics is added, the mixture is recovered at 37 ℃ and 200 rpm for 1 h, 100 mL of transformation solution is taken and spread on an Amp resistant LB solid plate, and the mixture is kept still and cultured at 37 ℃ overnight.

5. And (3) colony PCR verification: 10 single colonies were picked from the LB solid plate described above and mixed in a sterile PCR tube containing 10. mu.L of sterile double distilled water in order, and the resulting bacterial solution was used as a template for PCR amplification. In addition, a recombinant plasmid pETDuet was set_-1-adhA positive control C1 was used as a template, and a negative control C2 was used as a template in sterile double distilled water. After the PCR reaction, the PCR reaction was verified by agarose gel electrophoresis, and the verification result is shown in FIG. 2a, wherein all 10 single colonies picked up were positive and the verification was successful.

6. And (3) double enzyme digestion verification: taking a single colony solution with successful colony PCR verification to inoculate LB liquid containing 100 mu g/ml AmpIn a culture medium, cultured at 37 ℃ and 200 rpm for 12 hours, and then the plasmid was extracted using restriction enzyme NdeIAnd Xho ICarrying out double digestion on the plasmid, and verifying by agarose gel electrophoresis after the digestion is finishedadhAnd (3) if the connection is successful, the obtained verification result is shown in figure 2b, and the double enzyme digestion verification is successful.

7. Company sequencing: the recombinant plasmid which is successfully verified by colony PCR and double enzyme digestion is sent to a sequencing company for sequencing verification, the sequence obtained by sequencing is consistent with the known sequence, the verification is successful, and finally the recombinant plasmid pET22b-adh。

II,E.coli BL21 star (DE3)-pET22b-adhConstruction of (3) and SDS-PAGE protein expression verification

1. Recombinant strainE.coli BL21 star (DE3)-pET22b-adhConstruction of (3) and Induction culture thereof

(1) 50 μ L of expression competent cells were takenE.coliBL21 star (DE3) added with 5. mu.L of successfully sequenced recombinant plasmid pET22b-adhIce-bath is carried out for 30 min, then the mixture is thermally shocked in a water bath at 42 ℃ for 45 s, ice-bath is carried out immediately for 2 min, then 500 mu L of sterile LB liquid culture medium without antibiotics is added, the mixture is revived at 37 ℃ and 200 rpm for 1 h, then 100 mu L of transformation liquid is taken and spread on an LB solid plate containing ampicillin resistance, and the mixture is kept still and cultured overnight at 37 ℃. The next day, single colonies were picked from LB solid plates, transferred to 50 mL Erlenmeyer flasks containing 10 mL LB medium, and ampicillin was added to a concentration of 100. mu.g/mL, and cultured at 37 ℃ and 200 rpm for 12 h.

(2) The recombinant strain was inoculated at 1%E.coli BL21 star (DE3)-pET22b-adhInoculating into 50 mL Erlenmeyer flask containing 10 mL LBG medium, culturing at 37 deg.C and 200 rpm for about 3 h to OD₆₀₀0.2 mM IPTG was added at around 0.8, the temperature was lowered to 20 ℃ and the rotation speed was lowered to 100 rpm, and the induction culture was continued for 12 hours. Wherein the LBG culture medium comprises 10 g/L peptone, 5 g/L yeast powder, 10 g/L sodium chloride and 5 g/L glucose.

2. Control strainsE.coliConstruction of BL21 star (DE3) -pET22b and induction culture thereof

(1) 50 μ L of expression competent cells were takenE.coli BL21 star (DE3) 5 mu L of empty plasmid pET22b is added, ice bath is carried out for 30 min, then heat shock is carried out in water bath at 42 ℃ for 45 s, ice bath is carried out immediately for 2 min, 500 mu L of sterile LB liquid culture medium without antibiotics is added, recovery is carried out at 37 ℃ and 200 rpm for 1 h, 100 mu L of transformation solution is taken and spread on an LB solid plate containing ampicillin resistance, and standing culture is carried out at 37 ℃ overnight. The next day, single colonies were picked from LB solid plates, transferred to 50 mL Erlenmeyer flasks containing 10 mL LB medium, and ampicillin was added to a concentration of 100. mu.g/mL, and cultured at 37 ℃ and 200 rpm for 12 h.

(2) The recombinant strain is inoculated according to the inoculation amount of 1 percentE.coliBL21 star (DE3) -pET22b was inoculated into a 50 mL Erlenmeyer flask containing 10 mL LBG medium, incubated at 37 ℃ and 200 rpm for about 3 hours to OD₆₀₀0.2 mM IPTG was added at around 0.8, the temperature was lowered to 20 ℃ and the rotation speed was lowered to 100 rpm, and the induction culture was continued for 12 hours.

3. Recombinant strainE.coli BL21 star (DE3)-pET22b-adhProtein expression verification of

Each 1mL of the cell suspension obtained by the induction culture was centrifuged at 14000 rpm for 1 min, and the supernatant of the medium was removed to obtain cells. Resuspending and washing the thalli twice by sterile double distilled water, centrifuging at 14000 rpm for 1 min, removing supernatant to obtain thalli, and then adding 400 mu L of sterile double distilled water to resuspend the thalli; then the thalli is crushed by an ultrasonic crusher, the amplitude is set to be 60, the thalli is crushed for 5 s, and the process is stopped for 10 s until the bacterial liquid is transparent. And taking 30 mu L of the suspension for whole protein detection, centrifuging the rest 370 mu L of the suspension at 14000 rpm for 5 min, taking 30 mu L of supernatant as soluble protein for detection, re-suspending and washing the thalli by using sterile double distilled water for the obtained precipitate twice, then adding the sterile double distilled water for re-suspending and precipitating, and taking 30 mu L of the re-suspension as insoluble protein for detection. Adding 6 μ L of loading buffer solution into each 30 μ L of protein sample, mixing well, and performing lysis at 100 deg.C for 10 min by PCR instrument for denaturation. Finally, SDS-PAGE protein electrophoresis was performed to verify that the target protein ADH was expressed, mainly present in the supernatant and soluble as shown in FIG. 3.

Purification of NAD (NAD) (P) -dependent Alcohol Dehydrogenase (ADH)

The recombinant strain was inoculated at 1%E.coliBL21 star (DE3) -pET22b andE.coli BL21 star (DE3)-pET22b-adhinoculated in LBG liquid medium containing 100. mu.g/ml Amp, cultured at 37 ℃ and 200 rpm for about 3 hours to OD₆₀₀0.2 mM IPTG was added at around 0.8, the temperature was lowered to 20 ℃ and the rotation speed was lowered to 100 rpm, and the induction culture was continued for 12 hours. After the culture was completed, the cells were collected by centrifugation at 10000 rpm and 4 ℃ for 5 min, and then 5 mL of Binding Buffer (pH 7.4, 20mM NaH) was added to 1 g of the cells₂PO₄500 mM NaCl, 30 mM imidazole) was added to a Binding Buffer for resuspension; then crushing the thalli by using an ultrasonic crusher, setting the amplitude to be 60, crushing for 5 s, stopping for 10 s until the bacterial liquid is transparent, centrifuging for 15 min at 4 ℃ at 10000 rpm, and collecting supernatant, wherein the supernatant is the crude enzyme liquid. The protein concentration was quantified by the Bradford method, and the concentration of the protein in the obtained crude enzyme solution was 20 mg/ml.

5 mL of nickel column was selected as the separation and purification column, and the supernatant was passed through the nickel column, followed by washing the nickel column with Binding Buffer and then with Elution Buffer (pH 7.4, 20mM NaH)₂PO₄500 mM NaCl, 200 mM imidazole) to obtain an eluate, all on ice. The purity of the eluate was verified by SDS-PAGE, and the result is shown in FIG. 4. Elution Buffer containing 200 mM imidazole can elute ADH protein to obtain purified ADH protein. The resulting ADH protein was then concentrated and purified to a concentration of 20 mg/ml using a 10 kDa ultrafiltration tube for subsequent reactions.

Fourth, the verification that the pure enzyme liquid of NAD (NAD) (P) -dependent Alcohol Dehydrogenase (ADH) catalyzes the conversion of the allol into the d-psicose

500 mM of the substrate solution of allonol was prepared in double distilled water, and 20mM of NAD was prepared in double distilled water⁺The solution was made up of 20mM Na in double distilled water₂HPO₄-NaH₂PO₄Buffer (pH 7.0) to purify the ADH-purified enzyme solution as a biocatalyst. 1mL of the reaction system contained 700. mu.L of 20mM Na₂HPO₄-NaH₂PO₄Buffer (pH 7.0), 100. mu.L of 500 mM substrate solution of Allol, 100. mu.L of 20mM NAD⁺Solution and 100. mu.L of ADH purified enzyme solution. Mixing the above solutions, placing in a shaker at 50 deg.C and 200 rpm for reaction for 4 hThe reaction solution was analyzed by HPLC. The apparatus used was a Japanese Shimadzu liquid chromatograph, the detector was a differential Refractive Index Detector (RID), the column was a Carbomix Pb-NP 10: 8% (7.8X 300 mm, 10 μm) analytical column from Seiki technology, the mobile phase was double distilled water, the column temperature was 78 ℃, the flow rate was 0.5 ml/min, and the sample size was 10 μ l. The obtained HPLC spectrogram is shown in FIG. 5, and the ADH pure enzyme solution is verified to catalyze the conversion of the allonol into the d-psicose.

Example 2

1. Adding coenzyme NAD (NAD) by using crude NAD (P) -dependent Alcohol Dehydrogenase (ADH) enzyme solution⁺Under the condition of catalyzing the conversion of the allol into the D-psicose

500 mM of the substrate solution of allonol was prepared in double distilled water, and 20mM of NAD was prepared in double distilled water⁺The solution was made up of 20mM Na in double distilled water₂HPO₄-NaH₂PO₄The crude ADH enzyme solution obtained in example 1 was used as a biocatalyst in a buffer (pH 7.0). 1mL of the reaction system contained 700. mu.L of 20mM Na₂HPO₄-NaH₂PO₄Buffer (pH 7.0), 100. mu.L of 500 mM Allol substrate solution, 100. mu.L of 20mM NAD⁺Solution and 100. mu.L of crude ADH enzyme solution. The reaction mixture was placed in a shaker at 50 ℃ and 200 rpm for 6 hours, and the concentration of D-psicose obtained by detection and analysis of the reaction mixture by HPLC was about 3.5 g/L. The obtained HPLC spectrogram is shown in FIG. 6, and the crude ADH enzyme solution can catalyze the conversion of the allol into the d-psicose.

2. Using crude enzyme solution of NAD (P) -dependent Alcohol Dehydrogenase (ADH) without adding coenzyme NAD⁺Under the condition of catalyzing the conversion of the allol into the D-psicose

A500 mM substrate solution of allol was prepared in double distilled water, and the crude ADH enzyme solution obtained in example 1 was used as a biocatalyst. 1mL of the reaction system contained 100. mu.L of 500 mM of the substrate solution of allol and 900. mu.L of the crude enzyme solution of ADH. The reaction mixture was placed in a shaker at 50 ℃ and 200 rpm for 6 hours, and the concentration of d-psicose obtained by detection and analysis of the reaction mixture by HPLC was about 2.8 g/L. The HPLC chromatogram obtained is shown in FIG. 7, although the crude ADH enzyme solution was prepared without additional coenzyme NAD⁺Can also catalyze the conversion of the allol into d-psicose, butWith addition of coenzyme NAD⁺Compared with the prior art, the yield of the D-psicose is low, the dosage of the crude enzyme solution is large, and byproducts are easily generated.

The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions.

Sequence listing

<110> Qingdao Longding Biotechnology Co., Ltd

<120> a method for producing D-psicose by NAD (P) -dependent alcohol dehydrogenase catalysis

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<213> Gluconobacter frateurii

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Glu Ile Ala Leu Pro Ser Glu Leu Gly Pro Asn Asp Val Arg Ile Ala

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Ile His Thr Val Gly Ile Cys Gly Ser Asp Val His Tyr Tyr Thr His

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Gly Ala Ile Gly Pro Phe Val Val Arg Glu Pro Met Val Leu Gly His

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Glu Ala Ser Gly Thr Ile Thr Glu Ile Gly Ser Asn Val Arg Ser Leu

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Lys Val Gly Asp Arg Val Cys Met Glu Pro Gly Ile Pro Asp Pro Gln

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Ser Arg Ala Thr Leu Met Gly Gln Tyr Asn Val Asp Pro Ala Val Arg

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Phe Trp Ala Thr Pro Pro Ile His Gly Cys Leu Thr Pro Ser Val Val

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His Pro Ala Ala Phe Thr Phe Lys Leu Pro Asp Asn Val Ser Phe Ala

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Glu Gly Ala Met Ile Glu Pro Leu Ala Val Gly Val His Ala Ser Val

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Lys Ala Ala Ile Lys Pro Gly Asp Ile Cys Leu Val Thr Gly Cys Gly

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Pro Ile Gly Ile Met Thr Ala Leu Ala Ala Leu Ala Ser Gly Ala Gly

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Gln Val Phe Ile Thr Asp Leu Ala Pro Ala Lys Leu Ala Ile Ala Gly

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Gln Tyr Asp Gly Ile Arg Pro Ile Asn Val Arg Asp Glu Lys Pro Arg

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Asp Val Val Asp Ala Thr Cys Gly Ser Asp Trp Gly Val Asp Val Val

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Phe Glu Ala Ser Gly Phe Ala Gly Ala Tyr Asp Asp Ala Leu Ala Cys

245 250 255

Val Arg Pro Gly Gly Thr Ile Val Phe Val Gly Met Pro Ile Gln Lys

260 265 270

Val Pro Phe Asp Ile Val Ala Ala Gln Ala Lys Glu Ile Arg Met Glu

275 280 285

Thr Val Phe Arg Tyr Ala Asn Val Tyr Asp Arg Ala Ile Arg Leu Ile

290 295 300

Ser Ala Gly Lys Ile Asp Leu Lys Pro Leu Val Ser Glu Thr Phe Pro

305 310 315 320

Phe Asp Gln Gly Ile Ala Ala Phe Glu Arg Ala Ala Glu Ala Arg Pro

325 330 335

Ser Asp Val Lys Leu Gln Ile Val Leu

340 345

<210> 2

<211> 1038

<212> DNA

<213> Artificial Sequence (Artificial Sequence)

<400> 2

atggcccagg ccctggtgct ggaaaagaaa ggcgaactga gtctgcgcga aattgccctg 60

ccgagcgaac tgggtccgaa tgatgttcgt attgcaattc ataccgtggg catttgtggc 120

agcgatgtgc attattatac ccatggtgcc attggtccgt ttgttgttcg cgaaccgatg 180

gttctgggcc atgaagcaag tggcaccatt accgaaattg gtagtaatgt gcgcagtctg 240

aaagttggcg atcgtgtttg catggaaccg ggcattccgg atccgcagag tcgcgcaacc 300

ctgatgggtc agtataatgt ggatccggcc gtgcgctttt gggcaacccc gcctattcat 360

ggttgcctga ccccgagtgt ggtgcatccg gcagcattca cttttaaact gccggataat 420

gttagttttg ccgaaggcgc catgattgaa ccgctggcag tgggtgtgca tgcaagcgtg 480

aaagcagcca ttaagccggg tgacatttgt ctggtgaccg gctgcggtcc gattggtatt 540

atgaccgccc tggcagccct ggccagtggc gcaggtcagg tgtttattac cgatctggcc 600

ccggcaaaac tggcaattgc aggtcagtat gatggtattc gcccgattaa tgttcgtgat 660

gaaaaaccgc gtgatgtggt tgatgcaacc tgtggcagcg actggggtgt ggatgttgtg 720

tttgaagcaa gcggttttgc cggcgcatac gatgatgccc tggcctgcgt gcgtccgggc 780

ggtaccattg tgtttgtggg tatgccgatt cagaaagtgc cgtttgatat tgtggccgcc 840

caggcaaaag aaattcgtat ggaaaccgtg tttcgctatg ccaatgttta tgatcgtgca 900

attcgcctga ttagtgcagg caaaattgat ctgaaaccgc tggtgagcga aacctttccg 960

tttgatcagg gtattgccgc atttgaacgt gccgcagaag cacgcccgag cgatgttaaa 1020

ctgcagattg ttctgtaa 1038

<210> 3

<211> 38

<212> DNA

<213> Artificial Sequence (Artificial Sequence)

<400> 3

gggaattcca tatggcccag gccctggtgc tggaaaag 38

<210> 5

<211> 33

<212> DNA

<213> Artificial Sequence (Artificial Sequence)

<400> 5

ccgctcgagc agaacaatct gcagtttaac atc 33