ScienceAsia 32 Supplement 1 (2006): 025-030 |doi: 10.2306/scienceasia1513-1874.2006.32(s1).025

Vanadium Haloperoxidase from the Red Alga Gracilaria fisheri

Jirasak Kongkiattikajorn^* and Sayampong Pongdam

 
ABSTRACT: In this study, we isolated a vanadium-haloperoxidase from a marine red alga, Gracilaria fisheri and characterized it. Gracilaria fisheri, was collected on the Southern Thailand coast, at Kohyor Beach in Songklha province. The enzyme was purified by homogenization and centrifugation, acetone fractionation, ionexchange and gel filtration chromatography. Molecular weight was determined by gel chromatography and found to be approximately 615 kDa. The UV spectrum of the peroxidase did not show absorbance in the Soret band indicating a non-heme protein, like a vanadium-dependent haloperoxidase. Reconstitution experiments in the presence of several metal ions confirmed haloperoxidase requires vanadium for enzyme activity and showed that only vanadium completely restored the enzyme activity. The enzyme was moderately thermostable, keeping full activity up to 40^oC. Some preliminary steady-state kinetic studies were performed and apparent Michaelis-Menten kinetic parameters were determined for the substrates bromide and hydrogen peroxide.

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School of Bioresources and Technology, King Mongkut’ s University of Technology Thonburi, Thailand.

* Corresponding author, E-mail: jirasak.kon@kmutt.ac.th