Origin of the stereospecificity in binding hydroxamates of alpha- and beta-phenylalanine methylamide to thermolysin revealed by the X-ray crystallographic study.
Optically active N-formyl-N-hydroxy-alpha-phenylalanine methylamide (1) and N-formyl-N-hydroxy-beta-phenylalanine methylamide (2) were evaluated as inhibitors for thermolysin (TLN) to find that while the D-form is more potent than its enantiomer in the case of the hydroxamate of alpha-Phe-NHMe, in the inhibition with hydroxamate of beta-Phe-NHMe, the L-isomer (K(i)=1.66+/-0.05 microM) is more effective than its enantiomer. In order to shed light on the stereochemical preference observed in the inhibitions, X-ray crystallographic analyses of the crystalline TLN.D-1 and TLN.L-2 complexes were performed to the resolution of 2.1A. While L-2 binds TLN like substrate does with its benzyl aromatic ring occupying the S(1)' pocket, the electron density in the S(1)' pocket in the complex of TLN.D-1 is weak and could best be accounted for by the methylcarbamoyl moiety. For both inhibitors, the hydroxamate moiety coordinates the active site zinc ion in a bidentate fashion.
Kim
Seung-Jun
SJ
Center for Cellular Switch Protein Structure, Korea Research Institute of Bioscience and Biotechnology, 52 Euh-eun-dong, Yusong-gu, 305-806, Deajeon, South Korea.
Kim
Dong H
DH
Park
Jung Dae
JD
Woo
Joo-Rang
JR
Jin
Yonghao
Y
Ryu
Seong Eon
SE
D000577:Amides / Q000737:chemistry / Q000378:metabolism; D001665:Binding Sites; D018360:Crystallography, X-Ray; D006877:Hydroxamic Acids / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D010649:Phenylalanine / Q000737:chemistry / Q000378:metabolism*; D013237:Stereoisomerism; D013820:Thermolysin / Q000737:chemistry / Q000378:metabolism*
D000577:Amides; D006877:Hydroxamic Acids; D010649:Phenylalanine; D013820:Thermolysin