Yeast prohormone processing enzyme (KEX2 gene product) is a Ca2+-dependent serine protease.
The KEX2-encoded endoprotease was overproduced in yeast several hundred-fold and further purified to achieve a 10,000-fold enrichment in specific activity. The enzyme was (i) membrane-bound, but solubilized by detergents; (ii) able to cleave peptide substrates at both Lys-Arg and Arg-Arg sites; (iii) inhibited by EDTA and EGTA (but not o-phenanthroline), but fully reactivated by Ca2+; (iv) unaffected by 5-10 mM phenylmethylsulfonyl fluoride, N alpha-(ptosyl)lysine chloromethyl ketone, or L-1-tosylamido-2-phenylethyl chloromethyl ketone, but inactivated by 1-2 microM Ala-Lys-Arg-chloromethyl ketone; (v) labeled specifically by 125I-labeled Tyr-Ala-Lys-Arg-chloromethyl ketone; and (vi) resistant to trans-epoxysuccinate compounds (which inactivate thiol proteases), but inactivated by diisopropyl fluorophosphate (a diagnostic serine protease inhibitor). Mutant enzyme molecules lacking as many as 200 C-terminal residues still retained Ca2+-dependent protease activity and were labeled by 125I-labeled Tyr-Ala-Lys-Arg-chloromethyl ketone.
Fuller
R S
RS
Department of Biochemistry, University of California, Berkeley 94720.
Brake
A
A
Thorner
J
J
D001483:Base Sequence; D002872:Chromosome Deletion; D005796:Genes; D005800:Genes, Fungal; D007700:Kinetics; D008969:Molecular Sequence Data; D043484:Proprotein Convertases; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D012697:Serine Endopeptidases / Q000235:genetics* / Q000378:metabolism; D013381:Subtilisins
D029701:Saccharomyces cerevisiae Proteins; D043484:Proprotein Convertases; D012697:Serine Endopeptidases; D013381:Subtilisins; C058751:KEX2 protein, S cerevisiae