Insights into acylphosphatase structure and catalytic mechanism |
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Authors: | M Stefani N Taddei G Ramponi |
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Institution: | (1) Department of Biochemical Sciences, University of Florence, Viale Morgagni 50, I-50134 Florence (Italy), Fax +39 55 4222725, e-mail: stefani@cesit1.unifi.it, IT |
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Abstract: | Acylphosphatase is one of the smallest enzymes known (about 98 amino acid residues). It is present in organs and tissues
of vertebrate species as two isoenzymes sharing over 55% of sequence homology; these appear highly conserved in differing
species. The two isoenzymes can be involved in a number of physiological processes, though their effective biological function
is not still certain. The solution and crystal structures of different isoenzymes are known, revealing a close packed protein
with a fold similar to that shown by other phosphate-bind ing proteins. The structural data, together with an extended site-directed
mutagenesis investigation, led to the identification of the residues involved in enzyme catalysis. However, it appears unlikely
that these residues are able to perform the full catalytic cycle: a substrate-assisted catalytic mechanism has therefore been
proposed, in which the phosphate moiety of the substrate could act as a nucleophile activating the catalytic water molecule.
Received 12 November 1996; accepted 27 November 1996 |
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Keywords: | , Acylphosphatase isoenzymes, acylphosphatase, catalytic mechanism, acylphosphatase, catalytic residues, acylphosphatase,,,,,,structure, |
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