The conformational stability and flexibility of insulin with an additional intramolecular cross-link.


Abstract

The conformational stability and flexibility of insulin containing a cross-link between the alpha-amino group of the A-chain to the epsilon-amino group of Lys29 of the B-chain was examined. The cross-link varied in length from 2 to 12 carbon atoms. The conformational stability was determined by guanidine hydrochloride-induced equilibrium denaturation and flexibility was assessed by H2O/D2O amide exchange. The cross-link has substantial effects on both conformational stability and flexibility which depend on its length. In general, the addition of a cross-link enhances conformational stability and decreases flexibility. The optimal length for enhanced stability and decreased flexibility was the 6-carbon link. For the 6-carbon link the Gibbs free energy of unfolding was 8.0 kcal/mol compared to 4.5 kcal/mol for insulin, and the amide exchange rate decreased by at least 3-fold. A very short cross-link (i.e. the 2-carbon link) caused conformational strain that was detectable by a lack of stabilization in the Gibbs free energy of unfolding and enhancement in the amide exchange rate compared to insulin. The effect of the cross-link length on insulin hydrodynamic properties is discussed relative to previously obtained receptor binding results. Study holds ProTherm entries: 5157 Extra Details: additive : EDTA(1 mM), conformational stability; flexibility; H2O/D2O amide exchange;,hydrodynamic properties; receptor binding

Submission Details

ID: 8t5hLSwC

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:28 p.m.

Version: 1

Publication Details
Brems DN;Brown PL;Nakagawa SH;Tager HS,J. Biol. Chem. (1991) The conformational stability and flexibility of insulin with an additional intramolecular cross-link. PMID:1988440
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