Viral cysteine proteases are homologous to the trypsin-like family of serine proteases: structural and functional implications.

摘要: Abstract Proteases that are encoded by animal picornaviruses and plant como- potyviruses form a related group of cysteine-active-center enzymes essential for virus maturation. We show these proteins homologous to the family trypsin-like serine proteases. In our model, active-site nucleophile trypsin catalytic triad, Ser-195, is changed Cys residue in viral The other two residues His-57 Asp-102, otherwise absolutely conserved all protease sequences. Secondary structure analysis aligned sequences suggests location component strands twin beta-barrel fold Unexpectedly, 2a 3c subclasses cysteine proteases are, respectively, small large structural This classification allows molecular mapping from onto tertiary structures; we precisely identify amino acids strong determinants specificity both