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1k5s

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{{STRUCTURE_1k5s| PDB=1k5s | SCENE= }}
{{STRUCTURE_1k5s| PDB=1k5s | SCENE= }}
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'''PENICILLIN ACYLASE, MUTANT COMPLEXED WITH PPA'''
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===PENICILLIN ACYLASE, MUTANT COMPLEXED WITH PPA===
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==Overview==
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Penicillin acylase catalyses the condensation of Calpha-substituted phenylacetic acids with beta-lactam nucleophiles, producing semi-synthetic beta-lactam antibiotics. For efficient synthesis a low affinity for phenylacetic acid and a high affinity for Calpha-substituted phenylacetic acid derivatives is desirable. We made three active site mutants, alphaF146Y, betaF24A and alphaF146Y/betaF24A, which all had a 2- to 10-fold higher affinity for Calpha-substituted compounds than wild-type enzyme. In addition, betaF24A had a 20-fold reduced affinity for phenylacetic acid. The molecular basis of the improved properties was investigated by X-ray crystallography. These studies showed that the higher affinity of alphaF146Y for (R)-alpha-methylphenylacetic acid can be explained by van der Waals interactions between alphaY146:OH and the Calpha-substituent. The betaF24A mutation causes an opening of the phenylacetic acid binding site. Only (R)-alpha-methylphenylacetic acid, but not phenylacetic acid, induces a conformation with the ligand tightly bound, explaining the weak binding of phenylacetic acid. A comparison of the betaF24A structure with other open conformations of penicillin acylase showed that betaF24 has a fixed position, whereas alphaF146 acts as a flexible lid on the binding site and reorients its position to achieve optimal substrate binding.
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{{ABSTRACT_PUBMED_15254299}}
==About this Structure==
==About this Structure==
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[[Category: Helice]]
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[[Category: Ntn-hydrolase fold]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Jul 2 09:49:59 2008''

Revision as of 06:50, 2 July 2008

Image:1k5s.png

Template:STRUCTURE 1k5s

PENICILLIN ACYLASE, MUTANT COMPLEXED WITH PPA

Template:ABSTRACT PUBMED 15254299

About this Structure

1K5S is a Protein complex structure of sequences from Escherichia coli. Full crystallographic information is available from OCA.

Reference

Structural and kinetic studies on ligand binding in wild-type and active-site mutants of penicillin acylase., Alkema WB, Hensgens CM, Snijder HJ, Keizer E, Dijkstra BW, Janssen DB, Protein Eng Des Sel. 2004 May;17(5):473-80. Epub 2004 Jul 14. PMID:15254299

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