Studies of molecular crowding

1.用荧光去偏振法研究了尿素和氧化三甲基胺（TMAO）对α-糜蛋白酶（chy）和大豆胰蛋白酶抑制剂（STI）异缔合作用的影响。 STI用Alexa-488标记并用chy滴定。 的旋转弛豫时间的依赖性标记的STI后的浓度添加的HY的解释中的一个模型的上下文中，在该模型中，HY可以结合到两个独立的网站上的STI具有近似相等的亲和力。 在各种添加浓度的尿素和TMAO的存在下进行滴定，并且发现虽然添加的尿素倾向于抑制CY和STI的缔合，但TMAO增强了缔合。 结果对添加的尿素和TMAO的浓度的依赖性的分析表明，这两种效果，虽然在相反的方向，是加性的。（D.吴） 2.分析了浓缩拥挤剂对稀释反应物自缔合模型的整体影响，作为拥挤剂和反应物物种之间的排斥体积和吸引力相互作用的影响之和。（A.明顿）

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)