Aspects on the catalysis of lipase from porcine pancreas (type VI-s) in aqueous media: development of ion-pairs

Brazilian Archives of Biology and Technology

Marina Kokkinou¹  Leonidas G. Theodorou¹  Emmanuel M. Papamichael¹ 

[1] ,University of Ioannina Dept. of Chemistry Laboratory of EnzymologyIoannina,GREECE

关键词: Porcine Pancreas Lipase;    mechanism of hydrolysis;    p-nitrophenyl laurate;   

DOI  :  10.1590/S1516-89132012000200007

来源: SciELO

【 摘 要 】

This article reports a first contribution for the elucidation of catalytic mechanism of Lipase from porcine pancreas, type VI-s (PPL), in hydrolyzing an ester substrate in aqueous media. The conclusions were based on the pH-profiles of Michaelis-Menten parameters k cat/Km, k cat and Km, as well as on the absolute temperature profile of k cat/Km, obtained during the hydrolysis of p-nitrophenyl laurate by PPL. It was found that (a) PPL performs catalysis by means of ion pairs formed either as Ser152-Ο-/His263-Im+H and/or Carbonyl-Ο-/His263-Im+H, (b) the parameter k cat/Km equals to k1 and thus ES is formed and destroyed in the course of a series of consecutive reactions governed by the dynamic constant K S = k2/k1, and (c) the hydrolysis of substrate is assisted by a hydrogen bond developed between deprotonated Asp176 and the positively charged imidazole of His263 across a pKa-value 3.85, necessary for efficient catalysis.

【 授权许可】

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