In industrial application of NAD(P)H-dependent dehydrogenases, NAD(H) has the advantages over NADP(H) in higher stability, lower price and wider recycling system. Recently, a meso-2,6-diaminopimelate dehydrogenase from Symbiobacterium thermophilum (StDAPDH) has been found to be a useful biocatalyst for the production of D-amino acids, but it requires NADP(H) as co-enzyme. To switch the co-enzyme specificity from NADP(H) to NAD(H), we studied the effect of Y76 on the co-enzyme specificity of StDAPDH, because the crystal structural analysis indicated that residue Y76 is near the adenine ring. The mutation of Y76 exerted significant effect on the co-enzyme specificity. Furthermore, the double mutant R35S/R36V significantly lowered the specific activity toward NADP+, and the combination of R35S/R36V with some of the Y76 mutants resulted in mutant enzymes favorable NAD+ over NADP+. This study should provide useful guidance for the further development of highly active NAD(+)-dependent StDAPDH by enzyme engineering.
Amino Acid Oxidoreductases ; chemistry ; Amino Acids ; Clostridiales ; enzymology ; Mutation ; NAD ; NADP ; Substrate Specificity

Objective To explore the functional mechanism of a Chinese medicine compound “Qiangzhizufang”on rat model of Tourette syndrome ( TS) combined with fear.Methods The rat model of TS combined with fear was established by intraperitoneal injection of 3,3’-iminodipropionitrile (IDPN) combined with acoustic stimulation.After giving different drug lavage treatment, the changes of behavior of the rat models were assessed by field test and behavior test.The content of DA, TH and TH mRNA in the brain tissue was detected by HPLC, immunohistochemistry and RT-PCR, separately.Results Compared with the normal control group, stereotyped behavior and exercise behavior were increased, freezing time prolonged, but the content of DA, TH and TH mRNA in the brain tissue were not obviously changed in the model control group.Compared with the model control group, the stereotyped behavior and exercise behavior were decreased, content of DA, TH and TH mRNA in the brain tissue was decreased in the “Qiangzhizufang” group. Conclusions The Chinese medicine compound“Qiangzhizufang” can improve the behavior in rat models of TS combined with fear.This effect may be realized through down-regurating TH mRNA expression, reducing the content of TH, and reducing the dopamine synthesis.

Objective To study the effect of soluble, refolded, recombinant extracellular domain of the human Fc gamma receptor Ⅱ a (huFcγRⅡa) on the binding of human IgG to cells. Methods Extra-cellular domain of the huFcγRⅡ a gene was amplified from recombinant plasmid pe3huR Ⅱ by PCR and then cloned into pET-28a vector. The recombinant plasmid pETshuR Ⅱ was transformed into E. coli BL21 (DE3) after identified by PCR and doubly digested. The inclusion bodies of fusion protein were extracted and purified by washing, dissolved in 6 mol/L guanidine buffer, and refolded by rapid dilution technique. The refolding protein activity was tested by ELISA and flow cytometry. Results Extraceilular domain of the huFcγRⅡa gene was successfully cloned into pET-28a. The results of SDS-PAGE showed that the molecular mass (Mr) of the expressed protein was 24.8 × 103, and the expression rate was 30%. The purity of recom-binant shuR Ⅱ was up to 90% after washing. ELISA showed that the recombinant shuR Ⅱ was able to bind human IgG in a dose dependent manner, shuRⅡ could competitively inhibit the binding of human IgG to huFcγRⅡa expressed on the surface of COS-7 cells by flow cytometry. Conclusion The results demon-strate that it is possible to obtain large quantities of recombinant shuR Ⅱ which has comparable binding prep-erties to those of the whole membrane bound huFcγR Ⅱ a.

Objective Due to the superior performance,Carbon-Carbon composites,although still at their early stage of development,have gained more and more attention and showed great application potential.Methods According to the National Standard,the biological safety evaluation of carbon-carbon composites were done in the following aspects:cytotoxicity test,acute systemic toxicity test,haemolysis test,pyrogen test,intramuscular implantation test.Results test results showed the biological safety evaluation of carbon-carbon composites well meet the requirement of the national standard with fine biological compatibility.Conclusion The experiment results demonstrate that carbon-carbon composites can be put in clinical application

Objective: To evaluate the safety and efficacy of foam sclerotherapy for bleeding internal hemorrhoids. Methods: Consecutive adult patients (aged 18-60 years) with bleeding hemorrhoids were prospectively enrolled between March 2017 and March 2018. All patients were randomly assigned to the foam sclerotherapy (FS) group and the liquid sclerotherapy (LS) group. The foam and liquid sclerotherapy of hemorrhoids nucleus was performed by cap-assisted colonic endoscopy. Results: A total of 108 patients were enrolled, including 62 males (57.4%) with mean age of 44.0±7.6 years. There was no significant difference in gender, age, or body mass index between the FS (n = 55) group and the LS (n =53) group. The total amount of lauromacrogol injection in the FS group was 3.7±0.9 mL, which was significantly lower than that in the LS group (8.0±2.2 mL, P<0.001). In the LS group, 8 patients (15.1%) developed bleeding after needle removal, which was significantly higher than that in the FS group [5.5%(3/53), P=0.022]. Significant pain was found in 2 patients (3.8%) in the LS group and 0 in the FS group (P= 0.025). The short-term cure rate and effective rate of the FS group were 87.3% (48/55) and 9.1% (5/55), while those were 69.8% (37/53) and 22.6% (12/53) in the LS group, respectively (P=0.046). Conclusion Foam sclerotherapy is safe and effective in the treatment of bleeding internal hemorrhoids.