Catalytic residues and substrate specificity of scytalidoglutamic peptidase, the first member of the eqolisin in family (G1) of peptidases.
Scytalidoglutamic peptidase (SGP) is the first-discovered member of the eqolisin family of peptidases with a unique structure and a presumed novel catalytic dyad (E136 and Q53) [Fujinaga et al., PNAS 101 (2004) 3364-3369]. Mutants of SGP, E136A, Q53A, and Q53E lost both the autoprocessing and enzymatic activities of the wild-type enzyme. Coupled with the results from the structural analysis of SGP, Glu136 and Gln53 were identified as the catalytic residues. The substrate specificity of SGP is unique, particularly, in the preference at the P3 (basic amino acid), P1' (small a.a.), and P3' (basic a.a.) positions. Superior substrates and inhibitors have been synthesized for kinetic studies based on the results reported here. kcat, Km, and kcat/Km of SGP for D-Dap(MeNHBz)-GFKFF*ALRK(Dnp)-D-R-D-R were 34.8 s-1, 0.065 microM, and 535 microM-1 s-1, respectively. Ki of Ac-FKF-(3S,4S)-phenylstatinyl-LR-NH2 for SGP was 1.2x10(-10) M. Taken together, we can conclude that SGP has not only structural and catalytic novelties but also a unique subsite structure.
Kataoka
Yukiko
Y
Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan.
Takada
Katsumi
K
Oyama
Hiroshi
H
Tsunemi
Masahiko
M
James
Michael N G
MN
Oda
Kohei
K
D002384:Catalysis; D005658:Fungi / Q000201:enzymology* / Q000235:genetics; D018698:Glutamic Acid / Q000235:genetics / Q000378:metabolism*; D005973:Glutamine / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D009154:Mutation / Q000235:genetics; D010447:Peptide Hydrolases / Q000737:chemistry* / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D011480:Protease Inhibitors / Q000494:pharmacology; D013379:Substrate Specificity; D017186:Titrimetry
D011480:Protease Inhibitors; D005973:Glutamine; D018698:Glutamic Acid; D010447:Peptide Hydrolases