Purification and properties of a new enzyme, L-glutamate oxidase, from Streptomyces sp. X-119-6 grown on wheat bran.

Abstract

A new flavoprotein enzyme, L-glutamate oxidase, was purified to homogeneity from an aqueous extract of a wheat bran culture of Streptomyces sp. X-l 19-6. It showed absorption maxima at 273, 385 and 465nm and a shoulder around 490nm, and contained 2 mol of FADper mol of enzyme. The enzyme had a molecular weight of approximately 140,000 and consisted of three sizes of subunits with molecular weights of 44,000, 16,000 and 9,000. Balance studies showed that 1 mol of L-glutamate was converted to 1 mol of a-ketoglutarate, ammonia and hydrogen peroxide with the consumption of 1 mol of oxygen. In addition to L-glutamate, L-aspartate was oxidized by the enzyme but only to an extent of0.6% at pH 7.4; the Michaelis constants were as follows: 0.21 mM for L-glutamate and 29mMfor L-aspartate. The isoelectric point was pH 6.2, and the enzyme activity was optimal between pH 7.0 and 8.0. When the enzyme was heated at pH 5.5 for 15 min, the remaining activity was 100% of the original activity level at 65°C, 87% at 75°C and 47% at 85°C.

Glutamate detection by amino functionalized tetrahedral amorphous carbon surfaces

“…This is logical as the amount of protonated amine was higher on these surfaces. The protonated amine interacts with GlOx via electrostatic interaction as the isoelectric point of GlOx is pH 6.2 [27]. Consequently, the electrostatically adhered GlOx is washed away in the PBS washes and the activity reduced with time.…”

Electrochemical detection of hydrogen peroxide on platinum-containing tetrahedral amorphous carbon sensors and evaluation of their biofouling properties

“…It has also been suggested that H2O2 has a key role in aging [4]. Furthermore, it is formed as a by-product in various enzymatic reactions, such as those catalyzed by glucose oxidase [5], glutamate oxidase [6], and cholesterol oxidase [7]. Enzymatic production makes H2O2 feasible for biosensor applications as it typically has lower oxidation potential compared to the enzyme substrate molecules.…”

A Glass Capillary-Based Microsensor for L-Glutamate in in Vitro Uses

“…The pH range (pH 5.6-7.0) for the catalytic action of ascorbate oxidase is very close to that (pH 5.5-10.5) of GluOx (Kusakabe et al, 1983) , and hence both enzymes are active at pH 7.0.…”