期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1974
卷号：71
期号：4
页码：1351-1355
DOI：10.1073/pnas.71.4.1351
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The multisubunit enzyme aspartate transcarbamylase consists of six copies of two types of polypeptide chains, catalytic (C) and regulatory (R). A complex formed by the partial dissociation of this enzyme has been isolated. This species, which has the structure C6R4, is a likely intermediate in the stepwise dissociation of aspartate transcarbamylase induced by mercurials. The formation of the complex is the result of the release of a single regulatory dimer (R2) from the parent molecule. The specific activity of the intermediate is essentially the same as that of aspartate transcarbamylase. By contrast, both homotropic and heterotropic interactions are reduced, but not abolished. These observations suggest that the allosteric transitions involved in the control mechanisms do not require the intact structure C6R6.
关键词：thiols ; mercurials ; dissociation ; central cavity ; intermediate
