A kind of alcohol dehydrogenase mutant with improved enzyme activity and preparation method and application thereof
A technology of alcohol dehydrogenase and mutants, applied in the directions of oxidoreductase, fermentation, etc., can solve the problems of high price and low yield, and achieve the effects of reducing the amount of enzyme, reducing production cost, and achieving significant economic benefits
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Embodiment 1
[0028] Embodiment 1 Obtaining of wild-type alcohol dehydrogenase
[0029] Whole gene synthesis of the wild-type alcohol dehydrogenase gene shown in SEQ ID NO.2, and the following primers were designed according to the whole gene sequence:
[0030] PCR upstream primer: CTTTAAGAAGGAGATATACATATGAAAGCCGTCCAGTACACC
[0031] PCR downstream primer: GGCTTTGTTAGCAGCCGGATCTCATCAGGGAACCACCACGCC
[0032] Table 1 PCR reaction system
[0033] Reagent Dosage / μl PrimerStarPremix 25 PrimerFF 1 PrimerRR 1 DNA template 1 ddH2O 22
[0034] The PCR reaction conditions are as follows:
[0035] 98°C for 1min, 98°C for 10s, 55°C for 5s, 72°C for 5s / kbp, 30cycles, 16°C.
[0036] PCR amplification of wild-type alcohol dehydrogenase gene sequence;
[0037] Simultaneously perform PCR processing on the pET21a vector fragment:
[0038] PCR upstream primer: ATGTATATCTCTTCTTAAAG
[0039] PCR downstream primer: TGAGATCCGGCTGCTAACAAAGCCCCGAAAGG
[0040] The...
Embodiment 2
[0048] The acquisition of embodiment 2 alcohol dehydrogenase mutant
[0049] According to the three-dimensional structure of alcohol dehydrogenase (PDB: 2XAA), amino acids near the active center of alcohol dehydrogenase include F43, M47, Q51, A53, Y54, L119, A273, F281, F282, F286, Y294, W295. Since the amino acid changes near the active center may significantly affect the enzyme activity, the wild-type alcohol dehydrogenase was subjected to site-directed mutations by taking Q51, A53, Y54, A273, F286, and Y294 amino acid positions as examples. The primers listed in Table 2 were designed according to the mutation site.
[0050] Table 2 Site-directed mutagenesis primer sequences
[0051] Primer name Primer sequence KRED(ADH)_Q51M FF CCGGCGGCGATGTACGCCTAC KRED(ADH)_Q51M RR GTAGGCGTACATCGCCGCCGG KRED(ADH)_Q51L FF CCGGCGGCGCTGTACGCCTAC KRED(ADH)_Q51L RR GTAGGCGTACAGCGCCGCCGG KRED(ADH)_A53L FF GCGCAGTACCCTCTACGGCCTG KRED(ADH)_A53L...
Embodiment 3
[0080] The activity test of embodiment 3 alcohol dehydrogenase
[0081] The collected cells were resuspended to 3.5 g / L in 50 mM sodium phosphate buffer (pH 7.0), and homogenized twice using a high-pressure homogenizer and cell disruptor in an ice-water bath at 15,000 Psi to obtain a cell lysate.
[0082] The enzyme reaction activity system (5ml reaction system) includes: N-tert-butoxycarbonyl-piperidone 0.1g / ml, isopropanol 10% (v / v), Na 2 HPO 4 12H 2 O 24mg / ml, NaH 2 PO 4 2H 2 O 6.6mg / ml, MgCl 2 1mg / ml, coenzyme 0.4mg / ml, cell lysate 30% (v / v).
[0083] Place in a constant temperature shaker at 30°C and 200 rpm for reaction; after 15 hours of reaction, add 0.5ml of isopropanol; continue the reaction until the total reaction time is 22 hours. After the reaction, the sample was extracted by adding 2 times the volume of acetonitrile, centrifuged for 20 min to obtain the supernatant, filtered through a 0.45 μm filter membrane, detected by HPLC, and the conversion rate was...
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