title: Self-association of des-(B26-B30)-insulin. The effect of Ca2+ and some other divalent cations.
abstract: It has been confirmed by sedimentation equilibrium and sedimentation velocity experiments that des-(B26-B30)-insulin does not self-associate at neutral pH. Sedimentation equilibrium experiments at pH 7, 25 degrees C were conducted to investigate the effects of the structurally and physiologically important divalent cations Zn2+, Cd2+, Pb2+ and Ca2+ on the aggregation state of des-(B26-B30)-insulin (pig) in solution. It was found that all of these ions bring about association of this insulin analogue; Zn2+ and Cd2+ to a more marked degree than Pb2+ and Ca2+. The predominant species in solutions containing Zn2+ appear to be hexamers and hexameric aggregates, in those containing Cd2+, species up to and including tetramers, and in those containing Pb2+ and Ca2+, monomers and dimers of des-(B26-B30)-insulin appear to be the only species present. The possible significance of these findings, especially in relation to a role for Ca2+ in the action of insulin, is discussed.
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002413:Cations, Divalent; D007328:Insulin / Q000031:analogs & derivatives* / Q000378:metabolism; D008970:Molecular Weight; D011485:Protein Binding; D013329:Structure-Activity Relationship; D013552:Swine; D015032:Zinc
chemical_list: D002413:Cations, Divalent; D007328:Insulin; D015032:Zinc; D002118:Calcium