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：1994
卷号：91
期号：6
页码：2146-2150
DOI：10.1073/pnas.91.6.2146
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：A library of synthetic genes encoding 80- to 100-residue proteins composed mainly of random combinations of glutamine (Q), leucine (L), and arginine (R) has been expressed in Escherichia coli. These genes also encode an epitope tag and six carboxyl-terminal histidines. Screening of this library by immunoblotting showed that 5% of these QLR proteins are expressed at readily detectable levels. Three well-expressed QLR proteins were purified and characterized. Each of these proteins has significant alpha-helical content, is largely resistant to degradation by Pronase, and has a distinct oligomeric structure. In addition, one protein unfolds in a highly cooperative manner. These properties of the QLR proteins demonstrate that they possess folded structures with some native-like properties. The QLR proteins differ from most natural proteins, however, in being remarkably resistant to denaturant-induced and thermal-induced unfolding and in being relatively insoluble in the absence of denaturants.
