Evidence for the involvement of tyrosine-69 in the control of stereospecificity of porcine pancreatic phospholipase A sub(2)
The authors have studied the role of Tyr-69 of porcine pancreatic phospholipase A sub(2) in catalysis and substrate binding, using site-directed mutagenesis. A mutant was constructed containing Phe at position 69. Kinetic characterization revealed that the Phe-69 mutant has retained enzymatic activi...
Gespeichert in:
Veröffentlicht in: | Protein engineering 1989-01, Vol.2 (6), p.467-471 |
---|---|
Hauptverfasser: | , , , , |
Format: | Artikel |
Sprache: | eng |
Schlagworte: | |
Online-Zugang: | Volltext |
Tags: |
Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
|
Zusammenfassung: | The authors have studied the role of Tyr-69 of porcine pancreatic phospholipase A sub(2) in catalysis and substrate binding, using site-directed mutagenesis. A mutant was constructed containing Phe at position 69. Kinetic characterization revealed that the Phe-69 mutant has retained enzymatic activity on monomeric and micellar substrates, and that the mutation has only minor effects on k sub(cat) and K sub(m). The data suggest that in porcine pancreatic phospholipase A sub(2) the hydroxyl group of Tyr-69 serves to fix and orient the phosphate group of phospholipid monomers by hydrogen bonding. Because no such interaction can occur between the Phe-69 side-chain and the phosphate moiety of the substrate monomer, the mutant enzyme loses part of its stereospecificity but not its positional specificity. |
---|---|
ISSN: | 0269-2139 |