Characterization of bromoperoxidases (BPO) involved in the biosynthesis of halogenated secondary metabolites in red algae genus Laurencia

Ong, Cheng Yi (2008) Characterization of bromoperoxidases (BPO) involved in the biosynthesis of halogenated secondary metabolites in red algae genus Laurencia. Masters thesis, University Malaysia Sabah.

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Abstract

This study established the presence, activity and characterization of bromoperoxidases (BPO) in two species of red algae genus Laurencia; Laurencia snackyi and Laurencia similis, collected from the waters of Tunku Abdul Rahman Marine Park, Kota Kinabalu, Sabah, Malaysia. The presence and utilization of BPO by both the seaweed species were apparent with the isolation of halogenated secondary metabolites; 1) Laurencia snackyi yielded 5-acetoxypalisadin B (1), Palisadin A (2) and Aplysistatin (3), and 2) Laurencia similis yielded 1-methyl-2,3,5,6- tetrabromoindole (4) and 2,3,5,6-tetrabromoindole (5). The specific activity of the BPO enzyme extracted from L. snackyi was 6.3mU/mg and ooptimum pH for enzyme activity was pH 7. Studies on the metal ions that influence the enzyme activity showed the BPO enzyme from L. snackyi to be vanadium-dependent. The optimum temperature for BPO from this particular species was 25°C and it was thermostable up to 70°C. Meanwhile, the specific activity of BPO from L. simils was 7.1mU/mg. However, the BPO for this alga species exhibits a very unusual pH characteristic, where there are two optimal pH; 5 and 7, which leads to the assumption there are two different BPOs in L. similis. It was found that the BPO from L. simiIis was cuprum-dependent. This is the first report of a cuprum-dependent BPO. The optimum temperature for the BPO from L. similis was 30°C and was also thermostable up to 70°C. The kinetic data obtained shows that both BPO enzymes from L. snackyii and L. simils are non-homogenous and the substrates inhibit the enzyme reaction at high concentrations (more than 0.6 mM MCD, 20 mM H₂O₂, 200 mM KBr for L. snackyi and more than 0.8 mM MCD, 5 mM H₂O₂, 200 mM KBr for L. similis respectively). It was found that the BPO activity of L. similis was approximately 2.5 times higher than the BPO activity of L. snackyi. Both BPOs from the Laurencia exhibited 1000 times lower activity as compared to other seaweeds studied to date. The fact that both species investigated in this study are prolific producers of halogenated metabolites and are tropical algae could be factors that contribute to the lowered enzyme activity. The partially purified enzymes were found to be larger than 100 kDa. Further column chromatography and SDS PAGE for both Laurencia algae also support the possibility of two different BPOs present in L. similis and only one BPO in L. snackyi.

Item Type:Thesis (Masters)
Subjects:S Agriculture > SH Aquaculture. Fisheries. Angling
Divisions:SCHOOL > Borneo Marine Research Institute
ID Code:9095
Deposited By:IR Admin
Deposited On:23 May 2014 10:56
Last Modified:23 May 2014 10:56

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