Pakistan journal of biological sciences : PJBS

Activity and stability of uricase from Lactobacillus plantarum immobilizated on natural zeolite for uric acid biosensor.

PMID 24783814


Determination of uric acid concentration in human urine and blood is needed to diagnose several diseases, especially the occurrence of kidney disease in gout patients. Therefore, it is needed to develop a simple and inexpensive method for uric acid detection. The purpose of the research was to observe the use of Indonesian microbe that was immobilized on natural zeolite as a source of uricase for uric acid biosensor. Selection of mediators and determination of optimum condition measurement, the stability and kinetic properties of L. plantarum uricase were performed using carbon paste electrode. Cyclic voltammetry was employed to investigate the catalytic behavior of the biosensor. The result indicated that the best mediator for measurement of L. plantarum uricase activity was Qo (2,3-dimethoxy-5-methyl-1,4 benzoquinone). Optimum conditions for immobilization of L. plantarum uricase on zeolite were obtained at pH 7.6, with temperature of 28 degrees C, using uric acid concentration of 0.015 mM and zeolite mass at 135 mg K(M) and V(Max) of L. plantarum uricase obtained from Lineweaver-burk equation for the immobilization uricase on zeolite were 8.6728 x 10(-4) mM and 6.3052 mM, respectively. K(M) value of L. plantarum uricase directly immobilized onto the electrode surface was smaller than K(M) value of L. plantarum uricase immobilized on zeolite. The smaller K(M) value shows the higher affinity toward the substrate. The Electrode when kept at 10 degrees C was stable until 6 days, however the immobilized electrode on zeolite was stable until 18 days. Therefore, Indonesian L. plantarum could be used as a uric acid biosensor.