The temperature-sensitive bond in human alpha 2-macroglobulin is the alkylamine-reactive site.

Human a2-macroglobulin undergoes an autolytic peptide cleavage to give two large peptides, fragment I (M, = 115,000) and fragment I1 (Mr = 65,000) which account for the entire mass of the native subunits.This fragmentation, which was first reported by Harpel et al.