Folded proteins occur frequently in libraries of random amino acid sequences.

• DOI: 10.1073/pnas.91.6.2146
• Publication Date: 2006-05-31T13:05:57Z
• Authors: A R Davidson; R T Sauer
• Keywords: Pronase

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