What is the substrate used by xanthine oxidase?

Milk xanthine oxidase exhibits a broad substrate specificity that includes purines, aldehydes, and pteridines (1). The mechanism of substrate oxidation, particularly that of purines, has been the subject of several studies (2-4).

What is the cofactor for xanthine oxidase?

Crystallographic structure (monomer) of bovine xanthine oxidase. The bounded FAD (red), FeS-cluster (orange), the molybdopterin cofactor with molybdenum (yellow) and salicylate (blue) are indicated. Xanthine oxidase is defined as an enzyme activity (EC 1.17. 3.2).

Where is xanthine oxidase expressed?

This enzyme is expressed not only in vascular and endothelial cells but also circulates in the plasma. Vascular XO activity is regulated by NAD(P)H oxidase, since NADPH-driven generation of H2O2 stimulates xanthine oxidase activity.

How does allopurinol inhibit xanthine oxidase?

Allopurinol. Allopurinol, a xanthine oxidase inhibitor, acts as a neuroprotectant by preventing formation of free radicals that trigger programmed cell death. Free radical production occurs after reperfusion and reoxygenation after an hypoxic-ischemic insult.

How to prepare oxidase reagent for diagnostic use?

A. Preparation of 1% oxidase reagent from oxidase powder. To prevent deterioration of stock oxidase powder, the powder should be stored in a tightly sealed desiccator and kept in a cool, dark area. Kovac’s oxidase reagent is intended only for in vitro diagnostic use.

How to prepare Kovacs oxidase reagent for Neisseria?

1. Prepare a 1.0% Kovac’s oxidase reagent by dissolving 0.1 g of tetramethyl-p- phenylenediamine dihydrochloride into 10 ml of sterile distilled water. 2. Mix well and then let stand for 15 minutes. • The solution should be made fresh daily and the unused portion should be discarded.

What kind of dropper is used in Kovacs oxidase test?

Oxidase Reagent Droppers are used in the Kovacs oxidase test as a qualitative reaction in the identification of nonfermenters and miscellaneous gram-negative bacteria. Used in the identification of organisms which produce oxidase enzyme Oxidase Reagent Droppers contain 0.5 mL of a 1%…

What makes Kovac’s oxidase reagent turn into a purple compound?

Kovac’s oxidase reagent, tetramethyl-p-phenylenediamine dihydrochloride, is turned into a purple compound by organisms containing cytochrome c as part of their respiratory chain. This test aids in the recognition of H. influenzae, but other members of the genus Haemophilus, as well as unrelated bacterial species, may also give a positive reaction.