The First Component of Human Complement (C1): Kinetics of Reaction with its Natural Substrates

[摘要] Classical enzyme kinetic analyses were applied to define the mechanism of the effect of the fourth component (C4) on cleavage of the second component (C2) by the first component (C1) of human complement. The data indicated that the increased rate of cleavage of C2 by C1 in the presence of C4 was due to availability of a site for product deposition; the effect of C4 was reversed by blocking the site on C4 for C2 deposition. C2 cleavage by C1 followed first order kinetics.In addition, our findings support the hypothesis that there are separate enzymatic sites on the C1 molecule for its natural substrates.

[学科分类] 生物科学（综合）