Ion pairing between lipase and colipase plays a critical role in catalysis
| Autor: | Juan A. Hermoso, Laurence Ayvazian, Brigitte Kerfelec, Catherine Chapus, Isabelle Crenon, David Pignol |
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| Rok vydání: | 1998 |
| Předmět: |
Models
Molecular DNA Complementary Lysine Mutant Glutamic Acid Colipase Biochemistry Micelle Catalysis law.invention Cell Line Bile Acids and Salts law Animals Colipases Horses Lipase Molecular Biology Ternary complex Micelles biology Chemistry Cell Biology Glutamic acid biology.protein Recombinant DNA Mutagenesis Site-Directed |
| Zdroj: | The Journal of biological chemistry. 273(50) |
| ISSN: | 0021-9258 |
| Popis: | Among the polar interactions occurring in pancreatic lipase/colipase binding, only one ion pair involving lysine 400 on lipase and glutamic acid 45 on colipase has been described. These residues are strictly conserved among species, suggesting that the ion pair is likely to play an important role. Therefore, in order to prevent this interaction, mutations intended to neutralize or inverse the charge of these residues have been introduced in the cDNAs encoding horse lipase and colipase. The recombinant proteins have been expressed in insect cells, and their catalytic properties have been investigated. In all cases, preventing the formation of the correct ion pair Lys400/Glu45 leads to lipase-colipase complexes of reduced affinity unable to perform an efficient catalysis, notably in the presence of bile salt micelles. Diethyl p-nitrophenyl phosphate inhibition experiments with either mutant lipase or mutant colipase indicate a poor stabilization of the lipase flap. These results suggest that the ion pair plays a critical role in the active conformation of the lipase-colipase-micelle ternary complex by contributing to a correct orientation of colipase relative to lipase resulting in a proper opening of the flap. |
| Databáze: | OpenAIRE |
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