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| [[Image:1k5s.jpg|left|200px]] | | {{Seed}} |
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| {{STRUCTURE_1k5s| PDB=1k5s | SCENE= }} | | {{STRUCTURE_1k5s| PDB=1k5s | SCENE= }} |
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| '''PENICILLIN ACYLASE, MUTANT COMPLEXED WITH PPA'''
| | ===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.
| | The line below this paragraph, {{ABSTRACT_PUBMED_15254299}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 15254299 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_15254299}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Helice]] | | [[Category: Helice]] |
| [[Category: Ntn-hydrolase fold]] | | [[Category: Ntn-hydrolase fold]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 22:20:50 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Jul 2 09:49:59 2008'' |