ABSTRACT
BACKGROUND: LXYL-P1-2 is the first reported glycoside hydrolase that can catalyze the transformation of 7-b-xylosyl-10-deacetyltaxol (XDT) to 10-deacetyltaxol (DT) by removing the D-xylosyl group at the C7 position. Successful synthesis of paclitaxel by one-pot method combining the LXYL-P1-2 and 10- deacetylbaccatin III-10-b-O-acetyltransferase (DBAT) using XDT as a precursor, making LXYL-P1-2 a highly promising enzyme for the industrial production of paclitaxel. The aim of this study was to investigate the catalytic potential of LXYL-P1-2 stabilized on magnetic nanoparticles, the surface of which was modified by Ni2+-immobilized cross-linked Fe3O4@Histidine. RESULTS: The diameter of matrix was 2040 nm. The Km value of the immobilized LXYL-P1-2 catalyzing XDT (0.145 mM) was lower than that of the free enzyme (0.452 mM), and the kcat/Km value of immobilized enzyme (12.952 mM s 1 ) was higher than the free form (8.622 mM s 1 ). The immobilized form maintained 50% of its original activity after 15 cycles of reuse. In addition, the stability of immobilized LXYL-P1-2, maintained 84.67% of its initial activity, improved in comparison with free form after 30 d storage at 4 C. CONCLUSIONS: This investigation not only provides an effective procedure for biocatalytic production of DT, but also gives an insight into the application of magnetic material immobilization technology.
Subject(s)
Paclitaxel/biosynthesis , Glycoside Hydrolases/metabolism , Kinetics , Enzymes, Immobilized , Nanoparticles , MagnetsABSTRACT
Myeloid-derived suppressor cells (MDSCs) are newly discovered cells derived from bone marrow that suppress immunity, playing an immunosuppressive role in tumors, infections, and autoimmune diseases. It has been confirmed in disease model studies that their immunosuppressive effect is mainly achieved by suppressing the function of T cells. At present, the treatment of infectious diseases is still a major obstacle, especially in the treatment of chronic infectious diseases. Studies have found that MDSCs have increased aggregation in infectious diseases. As MDSCs are gaining more attention in infectious diseases, their potential therapeutic effects may be further explored. This article mainly reviews the immunosuppressive mechanisms of MDSCs in infections such as bacteria, viruses, parasites and fungi and their relationship with the diseases.
ABSTRACT
Aim To observe the effect of icariside Ⅱ(ICS Ⅱ)on cardiomyocyte apoptosis in spontaneously hypertensive rats (SHR)and to explore its possible mechanism. Methods Thirty male 13-week-old SHRs were randomly divided into model group,ICS Ⅱ low, medium,high and positive drug group (n = 6),ho-mologous male Wistar-Kyoto rats as control group (n =6). After a week of adaptive feeding,ICS Ⅱ low,me-dium and high dose groups were given ICS Ⅱ 4,8,16 mg · kg - 1 (ig,qd),and the positive drug group was given losartan 20 mg·kg - 1 . At the same time,the WKY and SHR group were given equal volume double distilled water. After 12 weeks of administration,the blood pressure was measured in rats. Then,the rats were sacrificed and the left ventricles were separated in order to calculate the left ventricular mass index. HE staining was used to observe the pathological changes of the left ventricle,and the apoptosis of the left ventricu-lar myocardium was detected by TUNEL staining. The expressions of Bcl-2 and Bax mRNA in left ventricle were detected by real time RT-PCR,and Bcl-2,Bax and cleaved-caspase-3 protein expressions were detec-ted by Western blot. Results Compared with WKY group,the blood pressure and left ventricular mass in-dex increased in SHR group (P < 0. 05),and the my-ocardial cell arrangement was disordered and the cell hypertrophy and apoptosis were obvious,accompanied by rupture of filament ;the level of Bax mRNA was up-regulated (P < 0. 05),and Bcl-2 mRNA was down-regulated (P < 0. 05 );the expressions of Bax and cleaved-caspase-3 protein were up-regulated (P <0. 05),and the level of Bcl-2 protein was down-regu-lated (P < 0. 05 ),and the ratio of Bax / Bcl-2 in-creased (P < 0. 05). Compared with SHR group,the blood pressure and left ventricular mass index de-creased in ICS Ⅱ middle,high group and the positive drug group (P < 0. 05);moreover,the arrangement of myocardial cells became more orderly,the cell hyper-trophy and the apoptosis of myocardial cells were im-proved;the level of Bax mRNA was down-regulated and Bcl-2 mRNA was up-regulated (P < 0. 05);the expression of Bax and cleaved-caspase3 protein were down-regulated and the level of Bcl-2 protein was up-regulated (P < 0. 05 );the ratio of Bax / Bcl-2 de-creased (P < 0. 05). Conclusions ICS Ⅱ can im-prove the left ventricular cardiomyocytes apoptosis in SHR,and its mechanism is related to the decrease of blood pressure and the inhibition of mitochondrial ap-optosis pathway.