1.Catalytic mechanism, molecular engineering and applications of threonine aldolases.
Qijia CHEN ; Xi CHEN ; Jianxiong HAO ; Dunming ZHU
Chinese Journal of Biotechnology 2021;37(12):4215-4230
Threonine aldolases catalyze the aldol condensation of aldehydes with glycine to furnish β-hydroxy-α-amino acid with two stereogenic centers in a single reaction. This is one of the most promising green methods for the synthesis of optically pure β-hydroxy-α-amino acid with high atomic economy and less negative environmental impact. Several threonine aldolases from different origins have been identified and characterized. The insufficient -carbon stereoselectivity and the challenges of balancing kinetic versus thermodynamic control to achieve the optimal optical purity and yield hampered the application of threonine aldolases. This review summarizes the recent advances in discovery, catalytic mechanism, high-throughput screening, molecular engineering and applications of threonine aldolases, with the aim to provide some insights for further research in this field.
Amino Acids
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Catalysis
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Glycine
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Glycine Hydroxymethyltransferase/metabolism*
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Kinetics
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Substrate Specificity
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Threonine
2.SHMT1 C1420T polymorphism contributes to the risk of non-Hodgkin lymphoma: evidence from 7309 patients.
Yi-Wei WANG ; Shao-Dan ZHANG ; Wen-Ji XUE ; Mei-Ling ZHU ; Lei-Zhen ZHENG
Chinese Journal of Cancer 2015;34(12):573-582
BACKGROUNDSerine hydroxymethyltransferase 1 (SHMT1) is a key enzyme in the folate metabolic pathway that plays an important role in biosynthesis by providing one carbon unit. SHMT1 C1420T may lead to the abnormal biosynthesis involved in DNA synthesis and methylation, and it may eventually increase cancer susceptibility. Many epidemiologic studies have explored the association between C1420T polymorphism and the risk of non-Hodgkin lymphoma (NHL), but the results have been contradictory. Therefore, we performed this meta-analysis to evaluate the relationship.
METHODSThe meta-analyses were conducted to evaluate the effect of SHMT1 C1420T polymorphism on NHL risk. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to measure the strength of the association.
RESULTSEight studies encompassing 3232 cases and 4077 controls were included. A statistically significant association was found between SHMT1 C1420T polymorphism and NHL risk under the allelic comparison (T vs. C: OR = 1.09, 95% CI 1.01-1.17); a borderline association was found between SHMT1 C1420T polymorphism and NHL risk under the homozygote model (TT vs. CC: OR = 1.18, 95% CI 1.00-1.39) and the dominant model (CT+TT vs. CC: OR = 1.10, 95% CI 1.00-1.21).
CONCLUSIONSHMT1 C1420T polymorphism may be associated with NHL risk, which needs to be validated in large, prospective studies.
Case-Control Studies ; Evidence-Based Medicine ; methods ; Genetic Predisposition to Disease ; Glycine Hydroxymethyltransferase ; genetics ; Humans ; Lymphoma, Non-Hodgkin ; genetics ; Neoplasm Proteins ; genetics ; Polymorphism, Single Nucleotide ; Publication Bias ; Sensitivity and Specificity
3.Construction of co-expression SHMT and TPase recombinant vector and dual-enzymatic synthesis of L-tryptophan.
Xin LI ; Jun LIU ; Qinqin ZHAO ; Aicai XU
Chinese Journal of Biotechnology 2010;26(9):1302-1308
Hydroxymethyltransferase (SHMT) and tryptophanase (TPase) are key enzymes in biosynthesis of L-tryptophan. We constructed three recombinant plasmids, including pET-SHMT, pET-TPase, and pET-ST for over-expression or co-expression of SHMT and TPase in Escherichia coli BL21 (DE3). The SDS-PAGE analysis showed that the recombinant proteins of 47 kDa and 50 kDa were expressed of pET-SHMT and pET-TPase, respectively. As compared to the host stain, the enzyme activity of SHMT and TPase was increased by 6.4 and 8.4 folds, respectively. Co-expression of both recombinant proteins, 47 kDa and 50 kDa, was also successful by using pET-ST and the enzyme activities were enhanced by 6.1 and 6.9 folds. We designed two pathways of dual-enzymatic synthesis of L-tryptophan by using these recombinant strains as source of SHMT and TPase. In the first pathway, the pET-SHMT carrying strain was used to catalyze synthesis of L-serine, which was further transformed into L-tryptophan by the pET-TPase expressing strain. These two steps sequentially took place in different bioreactors. In the second pathway, the pET-ST carrying strain, in which two enzymes were co-expressed, was used to catalyze simultaneously two steps in a single bioreactor. HPLC analysis indicated a high yield of 41.5 g/L of L-tryptophan was achieved in the first pathway, while a lower yield of 28.9 g/L was observed in the second pathway. In the first pathway, the calculated conversion rates for L-glycine and indole were 83.3% and 92.5%, respectively. In the second pathway, a comparable conversion rate, 82.7%, was achieved for L-glycine, while conversion of indole was much lower, only 82.9%.
Escherichia coli
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enzymology
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genetics
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metabolism
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Gene Expression Regulation, Bacterial
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physiology
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Gene Expression Regulation, Enzymologic
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physiology
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Genetic Vectors
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genetics
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Glycine Hydroxymethyltransferase
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biosynthesis
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genetics
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Plasmids
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genetics
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Recombinant Fusion Proteins
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biosynthesis
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genetics
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pharmacology
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Recombination, Genetic
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genetics
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Tryptophan
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biosynthesis
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Tryptophanase
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biosynthesis
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genetics