Synthesis of (S)-4-fluorophenylglycine by using immobilized amidase based on metal-organic framework / 生物工程学报

A stable Zr-based metal-organic framework (MOF, UiO-66-NH2) synthesized via micro-water solvothermal method was used to immobilize amidase by using the glutaraldehyde crosslinking method. The effect of immoblization conditions on enzyme immoblization efficiency was studied. An activity recovery rate of 86.4% and an enzyme loading of 115.3 mg/g were achieved under the optimal conditions: glutaraldehyde concentration of 1.0%, cross-linking time of 180 min, and the weight ratio of MOF to enzyme of 8:1. The optimal temperature and optimal pH of the immobilized amidase were determined to be 40 °C and 9.0, respectively, and the Km, Vmax and kcat of the immoblized amidase were 58.32 mmol/L, 16.23 μmol/(min·mg), and 1 670 s⁻¹, respectively. The immobilized enzyme was used for (S)-4-fluorophenylglycine synthesis and the optimal reaction conditions were 300 mmol/L of N-phenylacetyl-4-fluorophenylglycine, 10 g/L of immobilized enzyme loading, and reacting for 180 min at pH 9.0 and 40 °C. A conversion rate of 49.9% was achieved under the optimal conditions, and the conversion rate can be increased to 99.9% under the conditions of enantiomeric excess. The immobilized enzyme can be repeatedly used, 95.8% of its original activity can be retained after 20 cycles.

Drug resistance analysis of Neisseria gonorrhoeae and its related drug resistant gene detection / 国际检验医学杂志

Objective To understand the drug resistance of Neisseria gonorrhoeae in Foshan area and to detect the related drug resistant gene mutation situation.Methods 57 strains of Neisseria gonorrhoeae were collected.The drug susceptibility test was per-formed by adopting the agar dilution method.The related drug resistance genes were amplified by PCR and the PCR product se-quencing results were performed the homological searching in GenBank by the BLAST algorithm.Results The sensitive rates of Neisseria gonorrhoeae to penicillin,tetracycline,ciprooxacin,ceftriaxone and spectinomycin were 0.0%,8.8%,7.0%,61.4% and 100.0%,respectively.The rates of beta lactamase-producing Neisseria gonorrhoeae and tetracycline resistant Neisseria gonorrhoeae were 35.1% and 56.1%,respectively.The mutation rate of drug resistance genes were over 80%.Conclusion Ceftriaxone and spectinomycin can be used as the first choice drug for the treatment of Neisseria gonorrhoeae in Foshan region.The drug resistance mechanism of Neisseria gonorrhoeae is complex.The epidemiological monitoring of the Neisseria gonorrhoeae related drug resist-ance genes should be strengthened.