in equilibria containing low concentrations of free zinc ( free : bound ratios of 0.01-0.1:1 ) both insulin and proinsulin aggregated to form soluble hexamers containing firmly bound zinc ( up to 0.284g-atom/monomer ) with an apparent intrinsic association constant of 1.9x10 ( 6 ) m ( -1 ) .
C0021641
insulin
C0033362
proinsulin