1tlp
From Proteopedia
|
CRYSTALLOGRAPHIC STRUCTURAL ANALYSIS OF PHOSPHORAMIDATES AS INHIBITORS AND TRANSITION-STATE ANALOGS OF THERMOLYSIN
Overview
The mode of binding to thermolysin of the unsubstituted phosphoramidate, inhibitor N-phosphoryl-L-leucinamide (P-Leu-NH2) has been determined, crystallographically and refined at high resolution (R = 17.9% to 0.16-nm, resolution). The mode of binding of the naturally occurring thermolysin, inhibitor phosphoramidon reported previously [Weaver, L. H., Kester, W. R., and Matthews, B. W. (1977) J. Mol. Biol. 114, 119-132] has also been, confirmed by crystallographic refinement (R = 17.4% to 0.23-nm, resolution). Phosphoramidon binds to the enzyme with a single oxygen of, the phosphoramidate moiety as a zinc ligand. Together with three ligands, to the metal from the protein the resultant complex has approximately, tetrahedral geometry. However, in the case of P-Leu-NH2, two of the, phosphoramidate oxygens interact with the zinc to form a complex that, tends towards pentacoordinate. In this respect, P-Leu-NH2 appears to be a, better transition-state analog than is phosphoramidon. In addition, the, phosphorus-nitrogen bond length in P-Leu-NH2 is 0.18 nm, suggesting that, the nitrogen is protonated whereas the same bond in phosphoramidon is much, shorter (0.15 nm) suggesting that the nitrogen does not carry a charge. In, phosphoramidon the distance from the phosphoramide nitrogen to Glu-143 is, 0.39 nm whereas in P-Leu-NH2 this distance decreases to 0.34 nm. Taken, together, these observations provide additional evidence in support of the, participation of pentacoordinate intermediates in the mechanism of action, of thermolysin [Holmes, M. A. and Matthews, B. W. (1981) Biochemistry 20, 6912-6920] and the role of Glu-143 in first promoting the attack of a, water molecule on the carbonyl carbon of the scissile bond and, subsequently acting as a 'proton shuttle' to transfer the proton to the, leaving nitrogen [Monzingo, A. F. and Matthews, B. W. (1984) Biochemistry, 23, 5724-5729; Hangauer, D. G., Monzingo, A. F. and Matthews, B. W. (1984), Biochemistry 23, 5730-5741].
About this Structure
1TLP is a Single protein structure of sequence from [1] with RHA, CA and ZN as ligands. Active as Thermolysin, with EC number 3.4.24.27 Full crystallographic information is available from OCA.
Reference
Crystallographic structural analysis of phosphoramidates as inhibitors and transition-state analogs of thermolysin., Tronrud DE, Monzingo AF, Matthews BW, Eur J Biochem. 1986 Jun 2;157(2):261-8. PMID:3709536
Page seeded by OCA on Wed Nov 21 03:23:12 2007
