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Aminopeptidase from jumbo squid ( Dosidicus gigas ) hepatopancreas: purification, characterisation, and casein hydrolysis
Author(s) -
OsunaRuíz Idalia,
YepizPlascencia Gloria,
RouzaudSández Ofelia,
EzquerraBrauer Josafat Marina
Publication year - 2010
Publication title -
international journal of food science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.831
H-Index - 96
eISSN - 1365-2621
pISSN - 0950-5423
DOI - 10.1111/j.1365-2621.2009.02164.x
Subject(s) - chemistry , casein , enzyme , aminopeptidase , chromatography , hydrolysis , biochemistry , leucine , amino acid
Summary An aminopeptidase (AP) was partially purified from jumbo squid ( Dosidicus gigas ) hepatopancreas with 154.24‐fold and yield of 6.15%. The purification procedure consisted of ammonium sulphate fractionation and DEAE‐Sephacel chromatography. The enzyme was approximately 48–53 kDa as estimated by SDS‐PAGE. With l ‐leu‐ p ‐NA, it had optimum activity at pH 8.0 and 30 °C. The K m and V max / K m values of the enzymes for l ‐leu‐ p ‐NA were 0.326 m m and 2787 at 37 °C, respectively. Activation energy ( E a ) of the enzyme was 53.50 kJ M −1 .The AP showed activity against seven synthetic substrates: l ‐proline> l ‐methionine>Ac. l ‐γ‐glutamic> l ‐glycine> l ‐leucine> l ‐alanine> l ‐lysine‐ p ‐NA. The enzyme was strongly inhibited by Bestatin, partially inhibited by a metal‐chelating agent and by PCMB, a cystein protease inhibitor. Zn 2+ and (or) Ca 2+ seemed to be its metal cofactor(s). Incubation of casein with the partially purified AP resulted in a degree of hydrolysis of 6%.