Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.24.27 (thermolysin)
 1,894 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A bilin-containing fragment of the beta subunit of Porphyridium cruentum B-phycoerythrin produced by cleavage with thermolysin was shown by sequence analysis (Lundell, D.J., Glazer, A.N., DeLange, R.J., and Brown, D.M. (1984) J. Biol. Chem. 259, 5472-5480) to have the following structure. (Formula: see text) Secondary ion mass spectrometry of this bilin-peptide yielded a protonated molecular ion of 1629 mass units corresponding to that predicted from the composition of the fragment, and indicated that the heptapeptide is linked to ring A and the tripeptide to ring D. NMR spectra provided definitive evidence for a thioether linkage at the C-3' carbon of ring A and a second thioether linkage at teh C-18' carbon of ring D of the bilin. This is the first documented report of a bilin linked through two thioether linkages to a polypeptide.
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PMID:Bilin attachment sites in the alpha and beta subunits of B-phycoerythrin. Structural studies on a doubly peptide-linked phycoerythrobilin. 671 54

The metal-dependent deacetylase LpxC catalyzes the first committed step of lipid A biosynthesis in Gram-negative bacteria. Accordingly, LpxC is an attractive target for the development of inhibitors that may serve as potential new antibiotics for the treatment of Gram-negative bacterial infections. Here, we report the 2.7 A resolution X-ray crystal structure of LpxC complexed with the substrate analogue inhibitor TU-514 and the 2.0 A resolution structure of LpxC complexed with imidazole. The X-ray crystal structure of LpxC complexed with TU-514 allows for a detailed examination of the coordination geometry of the catalytic zinc ion and other enzyme-inhibitor interactions in the active site. The hydroxamate group of TU-514 forms a bidentate chelate complex with the zinc ion and makes hydrogen bond interactions with conserved active site residues E78, H265, and T191. The inhibitor C-4 hydroxyl group makes direct hydrogen bond interactions with E197 and H58. Finally, the C-3 myristate moiety of the inhibitor binds in the hydrophobic tunnel of the active site. These intermolecular interactions provide a foundation for understanding structural aspects of enzyme-substrate and enzyme-inhibitor affinity. Comparison of the TU-514 complex with cacodylate and imidazole complexes suggests a possible substrate diphosphate binding site and highlights residues that may stabilize the tetrahedral intermediate and its flanking transition states in catalysis. Evidence of a catalytic zinc ion in the native zinc enzyme coordinated by H79, H238, D242, and two water molecules with square pyramidal geometry is also presented. These results suggest that the native state of this metallohydrolase may contain a pentacoordinate zinc ion, which contrasts with the native states of archetypical zinc hydrolases such as thermolysin and carboxypeptidase A.
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PMID:Mechanistic inferences from the binding of ligands to LpxC, a metal-dependent deacetylase. 1680 Jun 20