کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5371972 | 1503973 | 2008 | 8 صفحه PDF | دانلود رایگان |

OCP1 and OCP2, the most abundant proteins in the cochlea, are putative subunits of an SCF E3 ubiquitin ligase. Previous work has demonstrated that they form a heterodimeric complex. The thermodynamic details of that interaction are herein examined by isothermal titration calorimetry. At 25 °C, addition of OCP1 to OCP2 yields an apparent association constant of 4.0 Ã 107 Mâ 1. Enthalpically-driven (ÎH = â 35.9 kcal/mol) and entropically unfavorable (â TÎS = 25.5 kcal/mol), the reaction is evidently unaccompanied by protonation/deprotonation events. ÎH is strongly dependent on temperature, with ÎCp = â 1.31 kcal molâ 1 Kâ 1. Addition of OCP2 to OCP1 produces a slightly less favorable ÎH, presumably due to the requirement for dissociation of the OCP2 homodimer prior to OCP1 binding. The thermodynamic signature for OCP1/OCP2 complex formation is inconsistent with a rigid-body association and suggests that the reaction is accompanied by a substantial degree of folding.
Journal: Biophysical Chemistry - Volume 134, Issues 1â2, April 2008, Pages 64-71