Modelling of the disulphide-swapped isomer of human insulin-like growth factor-1: implications for receptor binding

作     者：Gill, R Verma, C Wallach, B Urso, B Pitts, J Wollmer, A De Meyts, P Wood, S 

作者机构：Univ Klinikum Southampton Dept Biochem Sch Biol Sci Southampton SO16 7PX Hants England Univ York Dept Chem York UO1 5DD N Yorkshire England Hagedorn Res Inst DK-2820 Gentofte Denmark Univ London Birkbeck Coll Dept Crystallog London WC1E 7HX England Rhein Westfal TH Aachen Inst Biochem D-52057 Aachen Germany 

出 版 物：《PROTEIN ENGINEERING》 (蛋白质工程、设计与精选)

年 卷 期：1999年第12卷第4期

页      面：297-303页

核心收录：

学科分类：0710[理学-生物学] 071010[理学-生物化学与分子生物学] 07[理学] 0836[工学-生物工程] 

主　　题：insulin insulin-like growth factor-1 molecular dynamics receptor binding structure-function relationships 

摘      要：Insulin-like growth factor-1 (IGF-1) is a serum protein which unexpectedly folds to yield two stable tertiary structures with different disulphide connectivities;native IGF-1 [18-61,6-48,47-52] and IGF-1 swap [18-61,6-47, 48-52]. Here we demonstrate in detail the biological properties of recombinant human native IGF-1 and IGF-1 swap secreted from Saccharomyces cerevisiae, IGF-1 swap had a similar to 30 fold loss in affinity for the IGF-1 receptor overexpressed on BHK cells compared with native IGF-1,The parallel increase in dose required to induce negative cooperativity together with the parallel loss in mitogenicity in NIH 3T3 cells implies that disruption of the IGF-1 receptor binding interaction rather than restriction of a post-binding conformational change is responsible for the reduction in biological activity of IGF-1 swap. Interestingly, the affinity of IGF-I swap for the insulin receptor was similar to 200 fold lower than that of native IGF-1 indicating that the binding surface complementary to the insulin receptor (or the ability to attain it) is disturbed to a greater extent than that to the IGF-1 receptor. A 1.0 ns high-temperature molecular dynamics study of the local energy landscape of IGF-1 swap resulted in uncoiling of the first A-region a-helix and a rearrangement in the relative orientation of the A- and B-regions, The model of IGF-1 swap is structurally homologous to the NMR structure of insulin swap and CD spectra consistent with the model are presented. However, in the model of IGF-1 swap the C-region has filled the space where the first A-region a-helix has uncoiled and this may be hindering interaction of Val44 with the second insulin receptor binding pocket.