Objective To heterologously express and purify the small ubiquitin-like modifier(SUMO)tag fused organo-phosphorus hydrolase mutant H257Y/L303T(YT),namely SUMO-YT,and evaluate its hydrolytic capacity against ethyl paraoxon and soman.Methods The SUMO tag encoding gene was constructed at the N-terminus of the YT encoding gene with a linker sequence via enzyme digestion and ligation before SUMO-YT was expressed in Escherichia coli.SUMO-YT and YT were purified through ammonium sulfate precipitation and affinity chromatography to obtain high-purity target proteins.The activity and kinetic parameters of the recombinant enzymes were examined using ethyl paraoxon and soman as substrates.Results The system for expression and purification of recombinant enzymes was established,yielding SUMO-YT and YT,and the former exhibited more significantly enhanced hydrolytic efficiency than the latter,with catalytic rates 11-fold higher for paraoxon and 4.4-fold higher for soman.At 37 ℃ and pH 7.2,SUMO-YT reduced the inhibition rate of acetylcholinesterase(AChE)by soman from 100％to 45.7％within 3 minutes,whereas YT reduced it to no more than 80％.Conclusion The high-activity recombinant SUMO-YT is prepared.SUMO tag fusion can significantly enhance the hydrolytic capacity of YT against ethyl paraoxon and soman.

OBJECTIVE To heterologously express and purify bioscavenger organophosphorus hydrolase(OPH),and evaluate its ability to resist ethyl paraoxon poisoning in vivo.METHODS The Escherichia coli expression strain of OPH was constructed and purified by Ni-column affinity chroma-tography and gel filtration chromatography,and the purified product was identified by mass spectrometry.The enzyme activity and kinetic constants(Km,Vmax,kcat and kcat/Km)were measured using ethyl paraoxon as the substrate.Twelve SD rats were randomly divided into the experimental group and control group.The experimental group was given 1 mg·kg-1 of OPH solution by iv administration while the control group was given the same volume of normal saline.After administration,the two groups were immedi-ately sc administration with 2×LD50 ethyl paraoxon(0.86 mg·kg-1).The state of the rats was observed and the poisoning symptoms were scored.The survival rats were given 2×LD50 ethyl paraoxon every 24 h,and the survival curve and symptom score chart were drawn according to survival and poisoning symp-toms of the rats to evaluate the anti-organophosphorus poisoning ability of OPH.RESULTS The expres-sion strain of OPH in E.coli was successfully constructed.After two-step purification,a single band of OPH was obtained by sodium dodecyl sulphate-polyacrylamide gel electrophoresis,indicating that OPH had high purity,and the prepared protein sequence was consistent with the target protein.For OPH,Km=7.5×10-5 mol·L-1,Vmax=2.2×10-7 mol·L-1·s-1,kcat=158.4 s-1,kcat/Km=2.1×106 L·mol-1·s-1.The rats in the control group showed obvious poisoning symptoms after being given 2×LD50 ethyl paraoxon,and all rats died with in 15 min.The rats in the experimental group did not show poisoning symptoms after the first exposure,and the poisoning symptoms gradually deepened after continuous exposure until all the rats died on the 4th day.CONCLUSION OPH with high purity is successfully prepared in this study,and OPH could effectively resist ethyl paraoxon poisoning in rats.

Objective To compare epididymis-sparing orchiectomy (group A) with traditional orchiectomy (group B ) in patients with advanced prostate cancer,and to evaluate which procedure is better.Methods A total of 60 cases of advanced prostate cancer patients were enrolled,with 30 cases in group A and 30 cases in group B.They were given oral anti-androgen from 1 day after castration.Serum level of testosterone and prostatic specific antigen (PSA) was detected before castration,and 1 week,1,3,6,9 and 12 months after castration.Patient satisfaction was also evaluated.Results On time point of 12 months after castration,the average level of serum testosterone was 0.2 nmol/L (95 ％ confidence interval,0.1 ～ 0.9 nmol/L) in group A and 0.3 nmol/L (95％ confidence interval,0.2 ～ 0.9 nmol/L) in group B (P ＞0.05 ) ; the average value of PSA was 0.22 ng/ml in group A and 0.27 ng/ml in group B (P ＞0.05 ) ; patient satisfaction rate was 96.7％ (29/30) in group A and 53.3％ (16/30) in group B.Conclusions No significant difference of testosterone level and PSA is found between the 2 groups.However,epididymis-sparing orchiectomy meets the psychological needs better because it helps to maintain the appearance of the scrotum through epididymis preservation and epididymoplasty.