ALPHA(2)-MACROGLOBULIN BAIT REGION INTEGRITY - ROLE IN DETERMINING FAST-FORM STRUCTURE

To determine whether integrity of the bait region affects the structur e of the remainder of human alpha2-macroglobulin (alpha2M), we have de termined the separation between cysteine residues in a methylamine-rea cted fast-form of alpha2M. From reduction in fluorescence intensity of covalently-bound donor fluorophore caused by proximity to an acceptor , a separation of 35 +/- 8 angstrom was calculated, which is identical to a previously determined value for proteinase-treated fast-form alp ha2M. This indicates that although bait region cleavage is the physiol ogical route to conformational change in alpha2M, bait region integrit y per se does not significantly affect the structure of fast-form alph a2M.