SUBUNIT COMPOSITION OF PLASMA VONWILLEBRAND-FACTOR MULTIMERS - EVIDENCE FOR A NONPROTEOLYTIC MECHANISM RESULTING IN APPARENT INCREASE IN PROTEOLYTIC FRAGMENTS

被引:13
作者
TSAI, HM
NAGEL, RL
SUSSMAN, II
机构
[1] Division of Hematology, Montefiore Medical Center/Albert Einstein College of Medicine, Bronx
关键词
VONWILLEBRAND FACTOR; PROTEOLYSIS; PLATELET; RISTOCETIN;
D O I
10.1016/0049-3848(91)90280-A
中图分类号
R5 [内科学];
学科分类号
1002 ; 100201 ;
摘要
Plasma von Willebrand factor (vWf) consists of a series of multimers of different molecular sizes. When analyzed for subunit composition, plasma vWf contained a major polypeptide of approximately 225 kD, and at least three smaller proteolytic fragments. In the present study, the subunit composition of each of these multimers was analyzed using a two dimensional electrophoresis technique. Although nearly all the multimers, as separated by SDS 1.5% agarose gel electrophoresis, contained both the major polypeptide and the smaller fragments, the relative amount of the fragments varied among the multimers. The smaller multimers contained relatively more proteolytic fragments. After the larger multimers were depleted by incubation of plasma with formaldehyde-fixed platelets and ristocetin, the intact subunit decreased, while the amount of the proteolytic fragments remained relatively unchanged. The findings of this study are consistent with the scheme that plasma multimers undergo proteolytic cleavage after multimer assembly. Furthermore, an apparent increase in the amount of these proteolytic fragments may result from mechanisms unrelated to proteolysis, such as selective adsorption of the larger multimers onto platelets.
引用
收藏
页码:179 / 188
页数:10
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