CRYSTALLIZATION AND PRELIMINARY-X-RAY ANALYSIS OF METHYLAMINE-TREATED ALPHA-2-MACROGLOBULIN AND 3 ALPHA-2-MACROGLOBULIN PROTEINASE COMPLEXES

Crystals of methylamine-treated alpha-2-macroglobulin (alpha-2M-MA), alpha-2-macroglobulin in complex with two molecules of trypsin, alpha-2M-T2, one molecule of plasmin, alpha-2M-PL, and one molecule of plasmin followed by methylamine-treatment, alpha-2M-PL(MA), have reproducibly been obtained using ammonium sulfate or magnesium sulfate as precipitants. The crystals are fragile tetragonal bipyramids of up to 1.5 mm in length. Crystals of alpha-2M-MA diffracted to at least 9 angstrom resolution, crystals of alpha-2M-T2 diffracted to 10 angstrom resolution and crystals of alpha-2M-PL and alpha-2M-PL(MA) diffracted to 11 angstrom resolution. For alpha-2M-MA the cell parameters were determined as: a = b 257 angstrom, c = 555 angstrom; and for alpha-2M-T2 as: a = b = 247 angstrom, c = 559 angstrom. For both preparations the space group was I4(1)22. As estimated from density measurements, the crystals of alpha-2M-MA and alpha-2M-T2 contain one 360 kDa alpha-2M dimer per asymmetric unit. The volume of the asymmetric unit/molecular weight, V(m), was estimated at 5.6 angstrom 3/Da. The crystal parameters of alpha-2M-PL and alpha-2M-PL(MA) were not determined.