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1kec
From Proteopedia
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'''PENICILLIN ACYLASE MUTANT WITH PHENYL PROPRIONIC ACID''' | '''PENICILLIN ACYLASE MUTANT WITH PHENYL PROPRIONIC ACID''' | ||
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[[Category: Keizer, E.]] | [[Category: Keizer, E.]] | ||
[[Category: Snijder, H J.]] | [[Category: Snijder, H J.]] | ||
| - | [[Category: | + | [[Category: Beta-strand]] |
| - | [[Category: | + | [[Category: Helice]] |
| - | [[Category: | + | [[Category: Ntn-hydrolase fold]] |
| - | [[Category: | + | [[Category: Phenyl proprionic acid]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 22:38:19 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 19:38, 2 May 2008
PENICILLIN ACYLASE MUTANT WITH PHENYL PROPRIONIC ACID
Overview
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.
About this Structure
1KEC 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 Page seeded by OCA on Fri May 2 22:38:19 2008
