Enzymatic Digestion of the First Component of Human Complement (Clq)

[摘要] Human C1q was shown to be sensitive to digestion by trypsin, chymotrypsin and collagenase, but not by elastase. Treatment with trypsin and chymotrypsin caused a rapid loss of the hemolytic activity of C1q and its ability to fix to immune complexes. Collagenase digestion of C1q resulted in a rapid loss of the hemolytic activity also, whereas the ability to bind to immune complexes decreased slowly and remained at a constant value of 15%. In contrast to trypsin and chymotrypsin, collagenase treatment of 125I-labeled C1q led to well defined fragments, only some of which were labeled. Adsorption of collagenase-digested C1q on ovalbumin-antiovalbumin complexes indicated the larger non-covalently bound peripheral subunits of C1q to be involved in fixation to immune complexes. None of the fragments was able to initiate lysis in the presence of RC1q. Immunologic analysis of the digest revealed at least two different fragments with respect to antigenicity.

[学科分类] 生物科学（综合）