Introduction A biosensor is an analytical tool that comprises two essential components, an immobilized bio-component, in intimate contact with a transducer that converts a biological signal into a measurable electrical signal. Both electrochemical and optical transducers are mainly transduction methods that are employed in biosensor developments. This review summarises the studies carried on et...

Several different experimental approaches have shown the presence of tryptophan in malate dehydrogenase from pig heart mitochondria. The methods used were (a) fluorescence measurement of tryptophan content after acid hydrolysis and separation of amino acids by paper chromatography, (b) recovery of tryptophan labeled with tritium after incubation of the enzyme with tritiated substrates, (c) dete...

Sorbitol plays an important role in the osmotic regulation of the mammalian kidney. Sorbitol synthesis is regulated by the enzyme aldose reductase (AR) and its degradation to fructose is catalyzed by the enzyme sorbitol dehydrogenase (SDH). Various data exist on the polyol pathway on the rat kidney, but little is known about the distribution of the polyol pathway enzymes in the human kidney. De...

A bla(TEM-92) gene was cloned from a Proteus mirabilis isolate and expressed in Escherichia coli. Production of the enzyme caused reduction of susceptibility to penicillins and narrow- to expanded-spectrum cephalosporins but not to moxalactam and cephamycins. Determination of kinetic parameters with the purified enzyme revealed hydrolysis of expanded-spectrum cephalosporins, while cephamycins, ...

An enzyme that catalyzes the conversion of bovine proinsulin to insulin has been purified from a bovine pancreatic extract. The product of conversion was identified as insulin by aminoacid analysis and determination of carboxyl terminal aminoacid residues. The purified enzyme preparation showed one major protein band on polyacrylamide gel disc electrophoresis; it had a molecular weight of about...

We devised an enzyme immunoassay for plasma estrogen-like substances in pregnancy, using estriol covalently linked to horseradish peroxidase. Free and bound steroid were separated by use of polyethylene glycol reagent. The assay satisfies the normal criteria of specificity and precision. Results obtained by radioimmunoassay and enzyme immunoassay agreed well. Our assay is particularly applicabl...

The kinetic (KIE) and solvent (SIE) isotope effect methods were used to investigate the mechanism of enzymatic hydroxylation of halogenated derivatives of l-tyrosine to l-DOPA catalyzed by the enzyme tyrosinase (EC 1.14.18.1). The values of deuterium KIE and SIE were obtained using the non-competitive method with spectrophotometric measurements. The Lineweaver-Burk plots were used for determina...

We report the conditions (buffer composition and enzyme activity) required for estimating three frequently determined analytes--urea, glucose, and creatinine--by use of an improved version of the differential pH apparatus previously described (Clin Chem 29: 80-85, 1983). For each analyte, we used only one specific enzyme, thus avoiding a chain of auxiliary and indicator reactions. The method re...

Introduction The concentration of serum creatinine is widely used as an indicator of renal function. Sarcosine oxidase (SO) has been used in the enzymatic determination of creatinine in the clinical laboratory. SO has been isolated from various bacterial strains. It was first purified from Corynebacterium sp. U-96 (SO-U96) and shown to be a heterotetrameric enzyme. SO-U96 is a complex, bifuncti...