溶液流动对等电溶菌酶晶体生长的影响

本文对等温自由生长和强制性溶液生长的等电溶菌酶的晶体形态进行了研究,发现这些形态变化与溶液相的流动密切相关,指出生物晶体生长停止是由于生长晶体周围的溶质贫乏造成的;通过某些手段减薄或消除这一溶质贫乏区,就可以保证晶体的持续生长。本文的研究对改善大尺寸晶体的生长提供了一条途径。     

原发性高血压患者红细胞中存在抗高血压因子

本研究利用热处理和Sephadex G-150凝胶过滤层析等方法,从原发性高血压病患者(EHS)红细胞中部分纯化了抗高血压因子(AHF)。AHF具有热稳定性,分子量大于6kDa;能明显降低卒中易感型自发性高血压大鼠(SHR_(sp))血压,腹腔一次注入AHF(1.6mg/kg)30min后,SHR_(sp)收缩压从原来的27.6±0.7kPa降低到21.4±0.8kPa(p<0.001),4h后收缩压恢复至原水平。AHF能显著抑制自发性高血压大鼠(SHR)和肾性高血压大鼠(RHR)主动脉(A)及肠系膜动脉(MA)血管平滑肌(VSM)Ca~(2 )内流。且对MA Ca~(2 )内流的抑制作用强于A。以上结果表明:EHS红细胞中存在AHF,能显著降低高血压大鼠血压,其降压机制可能与其抑制VSM特别是小动脉VSM Ca~(2 )内流有关。     

Technetium labeling of monoclonal antibodies with functionalized BATOs: 2. TcCl(DMG)3CPITC labeling of B72.3 and NP-4 whole antibodies and NP-4 F(ab')2.

BATO (boronic acid adduct of technetium dioximes) complexes, TcCl(dioxime)3BR, were prepared in which the boron substituent (R) was the protein-reactive 2-carboxy-4-phenyl isothiocyanate (CPITC). The 99Tc complexes, where the dioxime was either dimethylglyoxime (DMG) or cyclohexanedione dioxime (CDO), were prepared and characterized. The 99mTc complex TcCl(DMG)3CPITC was prepared from a freeze-dried kit and used to label B72.3 (anti-TAG.72) and NP-4 (anti-CEA) whole antibodies, and the NP-4 F(ab')2 fragment. SDS-PAGE electrophoresis indicated that the labeling reagent was strongly bound to antibody. The labeled antibodies displayed high binding to affinity columns and good tumor uptake in GW39 tumor-bearing mice.     

A model for binding of an antifreeze polypeptide to ice.

A model is proposed, based on recent peptide analog and ice crystal etching studies, whereby an alanine-rich, alpha-helical antifreeze polypeptide (AFP) from the winter flounder inhibits the growth of ice crystals by hydrogen bonding of Thr, Asn, and Asp side chains in a specific pattern to the [2021] hexagonal bipyramidal planes of ice. It is further suggested that this mode of binding is unidirectional, maximizing opportunities for packing of AFPs on the ice surface, and that ice crystal growth inhibition occurs by a two-step mechanism involving hydrogen bonding and hydrophobic interpeptide interactions.     

A procedure for regenerating Japonica and Indica varieties of rice from protoplasts

Fertile rice plants have been regenerated from protoplasts of two japonica rice varieties (Radon and Baldo) using a protocol initially developed for plant regeneration from protoplasts of an indica rice. Embryogenic calli were developed from immature embryos of Radon and Baldo rice on a callus induction medium, and then used to establish cell suspensions. Protoplasts were isolated from the cell suspensions, and cultured on a Millipore filter placed on a Kao/agarose medium that contained cell clusters from suspensions of IR52 or IR45. The protoplasts grew vigorously on Kao medium and developed into embryogenic calli within two to three weeks. Somatic embryo development occurred during a subsequent transfer of the calli to an LS medium for two to three weeks. The calli were then transferred to MS or N6 plant regeneration medium, and within one to three weeks, plants regenerated from 21 to 32% of the Radon calli, and 33 to 35% of the Baldo calli. Based upon these results and the previous success in regenerating an indica variety from protoplasts, this procedure has great promise for regenerating a range of rice varieties, and probably for regeneration of other monocotyledonous plants from protoplasts     

Selenium-containing tRNAs from Clostridium sticklandii. Cochromatography of seleno-tRNA I with l-valyl-tRNA

It has been previously shown that Clostridium sticklandii specifically synthesized three readily separable ⁷⁵Se-labeled tRNAs, designated seleno-tRNAs I, II and III, and the partially purified seleno-tRNA II cochromatographed with l-prolyl-tRNA on DEAE-Sephadex A-50 (Chen, C.S. and Stadtman, T.C. (1980) Proc. Natl. Acad. Sci. U.S.A. 77, 1403–1407). In the present study a highly purified ⁷⁵Se-labeled tRNA I was obtained by chromatography on benzoylated DEAE-cellulose, DEAE-Sephadex A-50 and Sepharose 4B. The ⁷⁵Se-labeled tRNA I cochromatographed with an l-valine-accepting species on DEAE-Sephadex A-50 and Sepharose 4B. Addition of a 285-fold molar excess of unlabeled l-valine to the l-valine acceptor activity assay mixture markedly decreased the amount of l-[¹⁴C]valine bound to seleno-tRNA I.     

ZAKβ antagonizes and ameliorates the cardiac hypertrophic and apoptotic effects induced by ZAKα

ZAK (sterile alpha motif and leucine zipper containing kinase AZK), a serine/threonine kinase with multiple biochemical functions, has been associated with various cell processes, including cell proliferation, cell differentiation, and cardiac hypertrophy. In our previous reports, we found that the activation of ZAKα signaling was critical for cardiac hypertrophy. In this study, we show that the expression of ZAKα activated apoptosis through both a FAS‐dependent pathway and a mitochondria‐dependent pathway by subsequently inducing caspase‐3. ZAKβ, an isoform of ZAKα, is dramatically expressed during cardiac hypertrophy and apoptosis. The interaction between ZAKα and ZAKβ was demonstrated here using immunoprecipitation. The results show that ZAKβ has the ability to diminish the expression level of ZAKα. These findings reveal an inherent regulatory role of ZAKβ to antagonize ZAKα and to subsequently downregulate the cardiac hypertrophy and apoptosis induced by ZAKα.