A bienzyme electrode for L-malate based on a novel and general design.
The coimmobilization of a NAD(P) + -dependent dehydrogenase with salicylate hydroxylase (SHL, EC 1.14.13.1) in front of a Clark-electrode yields a flexible new design for dehydrogenase based biosensors. The feasibility of the approach has been tested with malic enzyme (MDH, EC 1.1.1.40) as the dehydrogenase, resulting in a novel L-malate sensor. It had substantial advantages over the biosensor approaches reported earlier: effective re-oxidation of NADPH by SHL yielded an extended linear range from 0.01 to 1.2 mmol 1(-1) L-malate and strongly reduced NADP+ -requirement (<0.025 mmol 1(-1)), while the working stability was increased to more than 30 days. The results obtained from six real samples showed a close correlation with the standard enzymatic method. The presented scheme with SHL and the Clark-electrode can be employed together with any NAD(P)+ -dependent dehydrogenase.
Gajovic
N
N
Potsdam University, Institute of Biochemistry and Molecular Physiology, Berlin, Germany. nenad.gajovic@t-online.de
Warsinke
A
A
Scheller
F W
FW
D015374:Biosensing Techniques; D001709:Biotechnology; D005069:Evaluation Studies as Topic; D005504:Food Analysis; D008291:Malate Dehydrogenase; D008293:Malates / Q000032:analysis*; D006899:Mixed Function Oxygenases; D009249:NADP; D012459:Salicylates; D020156:Salicylic Acid
D008293:Malates; D012459:Salicylates; D009249:NADP; C030298:malic acid; D006899:Mixed Function Oxygenases; D008291:Malate Dehydrogenase; C031917:malate dehydrogenase (oxaloacetate-decarboxylating) (NADP+); C022619:salicylate 1-monooxygenase; D020156:Salicylic Acid