The expression and purification of human rhinovirus protease 3C

Abstract

Human rhinovirus type 14 protease 3C was expressed as a soluble and active protein in Escherichia coli. The protease was purified by a cationic‐exchange step followed by gel filtration on a TSK 3000 column. The final yield of purified protease was in the range 0.5–1.0 mg/l culture grown to A550= 1.0. Sequence analysis revealed that greater than 90% of the N‐terminal residues were methionine. The enzyme activity of the purified protease was measured by cleavage of a synthetic peptide representing a predicted Gln/Gly viral polyprotein cleavage site. A mutant protease (Cys146→Ser) was produced and purified in the same way. The yield of mutant protease 3C was approximately 150 μg/l from a culture grown to A550= 1.0. This mutant protease 3C did not cleave the synthetic peptide substrate. Copyright © 1989, Wiley Blackwell. All rights reserved