Michon T, Sari J C, Granon S, Kerfelec B, Chapus C
Laboratoire de Biochimie et Technologie des Protéines INRA, Nantes, France.
Eur J Biochem. 1991 Oct 1;201(1):217-22. doi: 10.1111/j.1432-1033.1991.tb16277.x.
A complete microcalorimetric investigation of the interactions between the native subunits of the bovine pancreatic procarboxypeptidase A-S6 ternary complex has been performed. All the association constants and thermodynamic parameters associated with the reactions forming the various complexes have been determined. The influence of pH and ionic strength on the binding reactions has been investigated. Interestingly, the affinity between the subunits is not significantly modified by varying the ionic strength. In this respect, an enthalpy/entropy compensatory effect is observed for the binding of subunit III to subunit I when the ionic strength is increased, suggesting a physiological function for the association. The various pathways for formation of the ternary complex have been studied. Binding of subunit II (or III) to subunit I, the central element of the ternary complex, does not significantly modify the affinity of the other subunit for subunit I. From a thermodynamic point of view, the same final state is obtained whatever the pathway of ternary complex formation. This study is the first step of a kinetic investigation of the associated subunits.
已对牛胰羧肽酶原A - S6三元复合物天然亚基之间的相互作用进行了全面的微量量热研究。已确定了与形成各种复合物的反应相关的所有缔合常数和热力学参数。研究了pH和离子强度对结合反应的影响。有趣的是，改变离子强度不会显著改变亚基之间的亲和力。在这方面，当离子强度增加时，观察到亚基III与亚基I结合的焓/熵补偿效应，表明这种缔合具有生理功能。已研究了三元复合物形成的各种途径。亚基II（或III）与三元复合物的核心元件亚基I的结合，不会显著改变另一个亚基与亚基I的亲和力。从热力学角度来看，无论三元复合物形成的途径如何，都会得到相同的最终状态。这项研究是对相关亚基进行动力学研究的第一步。
