Studies of molecular crowding

分子拥挤的研究

• 批准号: 8741360
• 负责人: Allen P Minton
• 金额: $ 20.29万
• 依托单位: NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8741360
• 关键词: Affinity; Amines; Behavior; Binding; Biological; Complex; Crowding; Dependence; Elements; Fluorescence; Goals; Individual; Label; Liquid substance; Measurement; Methods; Modeling; Molecular; Oxides; Relaxation; Site; Soybeans; Sum; System; Thermodynamics; Time; Titrations; Trypsin Inhibitors; Urea; Work; base; chymotrypsin; chymotrypsin A; macromolecule; theories

1. The effect of urea and trimethyl-N-amine oxide (TMAO) upon the heteroassociation of alpha-chymotrypsin (chy) and soybean trypsin inhibitor (STI) was studied by measurement of fluorescence depolarization. STI was labeled with Alexa-488 and titrated with chy. The dependence of the rotational relaxation time of labeled STI upon the concentration of added chy was interpreted in the context of a model in which chy could bind to two independent sites on STI with approximately equal affinity. Titrations were conducted in the presence of various added concentrations of urea and TMAO, and it was found that while added urea tended to inhibit the association of chy and STI, TMAO enhanced the association. Analysis of the dependence of results upon the concentrations of added urea and TMAO showed that the two effects, although in opposite directions, were additive. (D. Wu) 2. The overall effect of a concentrated crowding agent upon a model for self-association of a dilute reactant was analyzed as the sum of the effects of both excluded volume and attractive interactions between the crowding agent and the reactant species. (A. Minton)

1. 采用荧光去极化法研究了尿素和氧化三甲基胺（TMAO）对α -凝乳胰蛋白酶（chy）和大豆胰蛋白酶抑制剂（STI）异交结合的影响。STI用Alexa-488标记，并用chy滴定。标记STI的旋转弛豫时间与添加的chy浓度的依赖关系是在一个模型的背景下解释的，其中chy可以以近似相等的亲和力结合到STI上的两个独立位点。在添加不同浓度的尿素和TMAO的情况下进行滴定，发现添加尿素倾向于抑制chy和STI的关联，而TMAO则增强了这种关联。对尿素和氧化三甲胺浓度对结果的依赖性分析表明，这两种作用虽然方向相反，但具有可加性。吴(d)