บทคัดย่องานวิจัย

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Purification and properties of tyrosinase isozymes from the gill of Lentinus edodes fruiting body.

Kanda, K.; Sato, T.; Ishii, S.; Enei, H.; Ejiri, S. I.;

Bioscience, Biotechnology and Biochemistry Year: 1996 Vol: 60 Issue: 8 Pages: 1273-1278 Ref: 27 ref.

1996

บทคัดย่อ

Purification and properties of tyrosinase isozymes from the gill of Lentinus edodes fruiting body.

Gill browning during postharvest preservation of L. edodes [Lentinula edodes] fruiting bodies, considered to be due to melanin biosynthesis started by tyrosinase [monophenol monooxygenase], is commercially undesirable since it causes an unpleasant appearance and development of an off-flavour. Six tyrosinase isozymes were purified from the browned gill of the fruiting body by ammonium sulfate fractionation, DEAE-Sephacel and Q-Sepharose column chromatography, and partially denaturing SDS-PAGE. At the step of Q-Sepharose column chromatography, 2 active fractions (A and B) were obtained. Each fraction was separated to 3 further fractions, A1, A2, and A3, and B1, B2, and B3, respectively, by partially denaturing SDS-PAGE. All these isozymes consisted of 2 types of polypeptides: alpha polypeptide (A alpha or B alpha ) and either beta (A beta or B beta ) or gamma polypeptide (A gamma or B gamma ). The alpha polypeptide contained the consensus amino acid sequence of the active site of known tyrosinases

, which is considered to act as a catalytic subunit. From the results of peptide mapping and the amino acid composition, A alpha and B alpha polypeptides were considered to be different proteins. The kinetic properties of the purified tyrosinase isozymes differed greatly according to whether they contained beta or gamma polypeptide, indicating these polypeptides to be a possible regulatory subunit.