British Nuclear Fuels Plc

Geoffrey William Garnham

Christopher Robin Lowe

Neil C Bruce

Harry Eccles

Biosensors for detecting nitrate or nitrite ions

A biosensor for detecting metal ions of elements such as Hg, Cr, As, Tc, Cu, Ag, Se, V, Mo and U which are capable of being reduced to metal by a reductase enzyme. The reductase enzyme is contained in an immobilized enzyme composition also including a cofactor and a coenzyme. The cofactor, for example NADPH, is oxidized by a reaction coupled with the reductase reduction of the metal ions and the cofactor in its oxidized state, e.g., NADP.sup.+, is re-reduced thereby maintaining a supply of the reduced state cofactor by action of the coenzyme in a further oxidation reaction coupled with the cofactor reduction. The further oxidation reaction may be oxidation of an alcohol to an aldehyde brought about by a dehydrogenase coenzyme. The oxidation brought about by the coenzyme, i.e., the amount of oxidized product, is a measure of the amount of oxidized state cofactor produced which, in turn, is a measure of the concentration of metal ions being detected. The amount of oxidation may be detected in one of a number of ways, especially by coupling the oxidation product with a reaction catalyzed by a light emitting coenzyme such as luciferase.

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Preston, United Kingdom

Geoffrey William Garnham