1. Characterization of hexose oxidase from the red seaweed <em>Chondrus crispus</em>.
- Author
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Groen, Barend W., De Vries, Simon, and Duine, Johannis A.
- Subjects
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OXIDASES , *CHONDRUS crispus , *MARINE algae , *RED algae , *FLAVINS , *ENZYMES , *PIGMENTS - Abstract
Hexose oxidase from the red seaweed, Chondrus crispus was purified to homogeneity: The enzyme appeared to be encapsulated in particles obtained alter mechanical disintegration of the fronds. Liberation of the enzyme in soluble form required either waiting for the spontaneous development of a suitable microbial flora in the suspension, or treatment with a mixture of proteases (pronase). As deduced from (SDS/)PAGE, the enzyme has a molecular mass of 87 kDa and probably consists of subunits of 36 kDa and 25 kDa. The low isoelectric point of 2.8 and the presence of 25 % (by mass) sugars indicate that the enzyme is a strongly acidic glycoprotein. The absorption spectrum of isolated enzyme minus that of the substrate-reduced enzyme, and the EPR spectrum of the free radical observed in the reduced enzyme revealed the presence of a flavin. This cofactor is probably covalently bound since flavins were not released upon denaturation of the enzyme by heat or acid treatment. Taking free FAD as a reference compound, the enzyme contains 1 mol flavin/mol enzyme. EPR spectroscopy of the purified preparation showed the presence of Cu2+. However, since the amount was substoichiometric, substrate addition did not affect the signal, and the addition of chelator or Cu2+ did not affect the activity, the presence of this metal ion seems adventitious. It is concluded that the large discrepancies between the presently and the previously reported [Sullivan, J. D. & Ikawa, M. (1973) Biochim. Biophys. Acre 309, 11–22] characteristics of the enzyme probably originate from the characterization of a contaminating protein in the latter case. [ABSTRACT FROM AUTHOR]
- Published
- 1997
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