Structure and Function of N-Terminal Zinc Finger Domain of SARS-CoV-2 NSP2

Virologica Sinica - SARS-CoV-2 has become a global pandemic threatening human health and safety. It is urgent to find effective therapeutic agents and targets with the continuous emergence of novel...     

昆虫锌金属蛋白酶研究进展

锌金属蛋白酶是指含有锌离子的蛋白酶,在哺乳动物中参与多项生物学过程的调控.在昆虫中也发现了许多锌金属蛋白酶,能够参与昆虫体内多项生命活动进程如食物的消化与吸收、组织重塑、变态发育、神经系统的调控及免疫防御反应等.本文综述了目前在昆虫中发现的锌金属蛋白酶的结构和底物特异性,聚焦6种锌金属蛋白酶(羧肽酶、基质金属蛋白酶、脑啡肽酶、胰岛素降解酶、血管紧缩素转换酶及氨肽酶)在昆虫中的功能,旨在为昆虫锌金属蛋白酶的深入研究提供参考.     

The effect of Cu,Zn and Fe chelates on the antioxidative status of thigh meat of broiler chickens

The studies aimed to verify the effect of Cu, Zn and Fe glycine chelate on the antioxidative status in the thigh meat of broiler chickens. The study assumption was that due to the antioxidative or prooxidative effect of Cu, Zn and Fe, these elements supplemented to chickens in an easily assimilable form would modify the antioxidative status of meat and those having a prooxidative effect could deteriorate the quality of meat. The experiment involved three hundred and fifty Ross 308 chickens divided into seven equipotent experimental groups. Over 42 days of the experiment, the chickens were administered Cu, Zn and Fe glycine chelates in an amount corresponding to 50% of the requirement (experimental factor I) or 25% of the requirement (experimental factor II). The level of oxidative stress indicators such as superoxide dismutase, catalase, glutathione, glutathione peroxidase and malondialdehyde was determined in the muscles and blood. The groups receiving Zn or Cu chelate showed statistically confirmed higher activity of superoxide dismutase, catalase, and a higher level of glutathione in comparison to the group receiving Fe chelate. In order to increase the antioxidative stability of thigh meat, it is sufficient that broiler chickens receive Zn or Cu in the form of glycine chelate in an amount covering 25% of their requirement of such minerals. On the other hand, the use of Fe glycine chelates decreased antioxidative stability due to an increase in the level of malondialdehyde, so it should be considered whether the administration of pro-oxidative Fe chelate to broilers is advisable.     

Green synthesis and characterization of zinc oxide nanoparticles using Cayratia pedata leaf extract

The synthesis of Zinc oxide nanoparticles using a plant-mediated approach is presented in this paper. The nanoparticles were successfully synthesized using the Nitrate derivative of Zinc and plant extract of the indigenous medicinal plant Cayratia pedata. 0.1 mM of Zn (NO₃)₂.6H₂O was made to react with the plant extract at different concentrations, and the reaction temperature was maintained at 55 °C, 65 °C, and 75 °C. The yellow coloured paste obtained was wholly dried, collected, and packed for further analysis. In the UV visible spectrometer (UV–Vis) absorption peak was observed at 320 nm, which is specific for Zinc oxide nanoparticles. The characterization carried out using Field Emission Scanning Electron Microscope (FESEM) reveals the presence of Zinc oxide nanoparticles in its agglomerated form. From the X-ray diffraction (XRD) pattern, the average size of the nanoparticles was estimated to be 52.24 nm. Energy Dispersive Spectrum (EDX) results show the composition of Zinc and Oxygen, giving strong energy signals of 78.32% and 12.78% for Zinc and Oxygen, respectively. Fourier Transform - Infra-Red (FT-IR) spectroscopic analysis shows absorption peak of Zn–O bonding between 400 and 600 cm^?1. The various characterization methods carried out confirm the formation of nano Zinc oxide. The synthesized nanoparticles were used in the immobilization of the enzyme Glucose oxidase. Relative activity of 60% was obtained when Glucose oxidase was immobilized with the green synthesized ZnO nanoparticles. A comparative study of the green synthesized with native ZnO was also carried out. This green method of synthesis was found to be cost-effective and eco-friendly.     

Ago-Allosteric Modulation and Other Types of Allostery in Dimeric 7TM Receptors

Conventionally, an allosteric modulator is neutral in respect of efficacy and binds to a receptor site distant from the orthosteric site of the endogenous agonist. However, recently compounds being ago-allosteric modulators have been described i.e., compounds acting both as agonists on their own and as enhancers for the endogenous agonists in both increasing agonist potency and providing additive efficacy—superagonism. The additive efficacy can also be observed with agonists, which are neutral or even negative modulators of the potency of the endogenous ligand. Based on the prevailing dimeric concept for 7TM receptors, it is proposed that the ago-allosteric modulators bind in the orthosteric binding site, but–importantly–in the “other” or allosteric protomer of the dimer. Hereby, they can act both as additive co-agonists, and through intermolecular cooperative effects between the protomers, they may influence the potency of the endogenous agonist. It is of interest that at least some endogenous agonists can only occupy one protomer of a dimeric 7TM receptor complex at a time and thereby they leave the orthosteric binding site in the allosteric protomer free, potentially for binding of exogenous, allosteric modulators. If the allosteric modulator is an agonist, it is an ago-allosteric modulator; if it is neutral, it is a classical enhancer. Molecular mapping in hetero-dimeric class-C receptors, where the endogenous agonist clearly binds only in one protomer, supports the notion that allosteric modulators can act through binding in the “other” protomer. It is suggested that for the in vivo, clinical setting a positive ago-allosteric modulator should be the preferred agonist drug.     

Antibacterial Schiff Bases of Oxalyl-hydrazine/diamide Incorporating Pyrrolyl and Salicylyl Moieties and of Their Zinc(II) Complexes

Schiff bases derived from oxaldiamide/oxalylhydrazine and pyrrol-2-carbaldehyde, or salicylaldehyde respectively, as well as their Zn(II) complexes have been prepared and tested as antibacterial agents. These Schiff bases function as tetradentate ligands, forming octahedral Zn(II) complexes. The ketonic form for the diamide derived Schiff base and the enolic form of the hydrazide derived Schiff base were the preferred tautomers for coordination of the metal ions. The title compounds and their Zn(II) derivatives were evaluated for antibacterial activity against several bacterial strains which easily develop resistance to classical antibiotics, such as Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. Some of them showed promising biological activity in inhibiting the growth of such organisms.     

Histopathology and cytotoxicity as biomarkers in treated rats with cadmium and some therapeutic agents

The present study aimed to investigate the protective role of ascorbic acid (vitamin C) and zinc (Zn) against cadmium (Cd) induced histopathological changes in tissues of liver, kidney, lung and testis of rats as well as chromosomal aberrations. For this purpose, 60 male albino rats were divided into six groups; each group contained 10 animals. The first group served as control and was given only distilled water. The second and third groups received distilled water supplemented with 2 g ascorbic acid/l and 500 mg Zn/l, respectively. The fourth group received a daily oral dose containing 3 mg Cd/kg b.w. (1/30 LD₅₀). The fifth group received Cd + ascorbic acid (3 mg Cd/kg b.w. + 2 g ascorbic acid/l), while the sixth group received Cd + Zn (3 mg Cd/kg b.w. +500 mg Zn/l). The treatment in all groups lasted for 90 consecutive days. Rats exposed to cadmium showed severe histopathological changes in the liver, kidney, lung and testicular tissues as well as chromosomal aberrations such as: break, ring, centromeric separation and polyploidy. Co-treatment with zinc partially improved the histopathological changes and chromosomal aberrations while co-treatment with vitamin C exhibited a more protective role and markedly reduced tissues damage induced by Cd.     

锌指核酸酶技术在植物基因工程中的应用

锌指核酸酶(zinc finger nucleases,ZFNs)由3到4个锌指结构(zinc fingers,ZFs)和FokⅠ核酸内切酶的剪切结构域组成。锌指核酸酶(ZFNs)通过锌指结构(ZFs)与特异核酸位点结合,再利用FokⅠ的酶切作用切割DNA,引起特异位点DNA双链断裂(double strand break,DSB)。DNA双链断裂可以通过非同源末端连接(non-homologous end joining,NHEJ) 或同源重组(homologous recombination,HR)来修复。在修复过程中实现对基因组DNA的靶向修饰。介绍了锌指核酸酶结构、人工构建途径,作用机理和试验步骤,重点综述了锌指核酸酶技术在植物基因工程的应用。