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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'' |
Revision as of 06:50, 2 July 2008
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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