Molecular engineering of transketolase from Escherichia coli and tartaric semialdehyde biosynthesis / 生物工程学报

Transketolase (EC 2.2.1.1, TK) is a thiamine diphosphate-dependent enzyme that catalyzes the transfer of a two-carbon hydroxyacetyl unit with reversible C-C bond cleavage and formation. It is widely used in the production of chemicals, drug precursors, and asymmetric synthesis by cascade enzyme catalysis. In this paper, the activity of transketolase TKTA from Escherichia coli K12 on non-phosphorylated substrates was enhanced through site-directed saturation mutation and combined mutation. On this basis, the synthesis of tartaric semialdehyde was explored. The results showed that the optimal reaction temperature and pH of TKTA_M (R358I/H461S/R520Q) were 32 ℃ and 7.0, respectively. The specific activity on d-glyceraldehyde was (6.57±0.14) U/mg, which was 9.25 times higher than that of the wild type ((0.71±0.02) U/mg). Based on the characterization of TKTA_M, tartaric acid semialdehyde was synthesized with 50 mmol/L 5-keto-d-gluconate and 50 mmol/L non-phosphorylated ethanolaldehyde. The final yield of tartaric acid semialdehyde was 3.71 g with a molar conversion rate of 55.34%. Hence, the results may facilitate the preparation of l-(+)-tartaric acid from biomass, and provide an example for transketolase-catalyzed non-phosphorylated substrates.

Synthesis of pyrroloquinoline quinone by recombinant Gluconobacter oxydans / 生物工程学报

Pyrroloquinoline quinone (PQQ), an important redox enzyme cofactor, has many physiological and biochemical functions, and is widely used in food, medicine, health and agriculture industry. In this study, PQQ production by recombinant Gluconobacter oxydans was investigated. First, to reduce the by-product of acetic acid, the recombinant strain G. oxydans T1 was constructed, in which the pyruvate decarboxylase (GOX1081) was knocked out. Then the pqqABCDE gene cluster and tldD gene were fused under the control of endogenous constitutive promoter P0169, to generate the recombinant strain G. oxydans T2. Finally, the medium composition and fermentation conditions were optimized. The biomass of G. oxydans T1 and G. oxydans T2 were increased by 43.02% and 38.76% respectively, and the PQQ production was 4.82 and 20.5 times higher than that of the wild strain, respectively. Furthermore, the carbon sources and culture conditions of G. oxydans T2 were optimized, resulting in a final PQQ yield of (51.32±0.899 7 mg/L), 345.6 times higher than that of the wild strain. In all, the biomass of G. oxydans and the yield of PQQ can be effectively increased by genetic engineering.

Effect of comprehensive medical goal appraisal on hand hygiene compli-ance rate of health care workers / 中国感染控制杂志

Objective To evaluate the comprehensive medical goal appraisal system on hand hygiene compliance rate of health care workers(HCWs).Methods Comprehensive medical goal appraisal system was adopted to inter-vene hand hygiene compliance rate of HCWs in a comprehensive hospital ,hand hygiene compliance rates of HCWs and consumption of instant hand sanitizer per bed-day before (December 2012)and after intervention (January 2013-June 2014)were compared.Results Hand hygiene compliance rate after intervention was higher than before interven-tion (85.17% [18 208/21 379]vs 39.92%[853/2 137]),hand hygiene compliance rate enhanced by 113.35%(χ2 =2 590. 81,P 90%),consumption of instant hand sanitizer before and after intervention was 7.24 mL/bed-day(4 200 L/579 841 bed-day)and 10.54 mL/bed-day(9 323.5L/884 489 bed-day)respectively,the consumption after intervention increased by 45.58% compared with that before intervention. Conclusion Comprehensive medical goal appraisal can effectively enhance hand hygiene compliance rate ,and maintains at a high level;the measure can affect hand hygiene behavior of HCWs by hawthorne effect,and is an effective and long-term measure to improve hand hygiene compliance of HCWs.

Efficacy and safety of Bicalutamide 150 mg as the monotherapy in the treatment of locally advanced prostate cancer / 中华泌尿外科杂志

vides com-parable efficacy with medical castration in regard of decreasing PSA level and reducing prostate vol-ume. It is a safe and well tolerated treatment option as well.