What is hypoxanthine and xanthine?

Unsalvaged hypoxanthine is oxidized to xanthine, which is further oxidized to uric acid by xanthine oxidase. Molecular oxygen, the oxidant in both reactions, is reduced to H2O2 and other reactive oxygen species. In humans, uric acid is the final product of purine degradation and is excreted in the urine. Figure 19-4.

What enzyme converts hypoxanthine to xanthine?

xanthine oxidoreductase
The enzyme xanthine oxidoreductase (XOR) converts hypoxanthine to xanthine and the latter to uric acid, which are the last two steps of purine catabolism in the highest uricotelic primates.

Is hypoxanthine an amino acid?

Human hypoxanthine (guanine) phosphoribosyltransferase: an amino acid substitution in a mutant form of the enzyme isolated from a patient with gout.

What is the purpose of xanthine?

Clinical significance. Derivatives of xanthine (known collectively as xanthines) are a group of alkaloids commonly used for their effects as mild stimulants and as bronchodilators, notably in the treatment of asthma or influenza symptoms.

What is hypoxanthine in fish?

Hypoxanthine is regarded as the major catabolite of adenosine triphosphate (ATP) and it is a useful indicator of freshness because of its gradual accumulation in seafood. Hx value rapidly increases in ice storage and the content of the muscle is used for the determination of the post-mortem age in seafood.

What does hypoxanthine bind?

Hypoxanthine, a naturally occurring purine derivative, has been shown to form Watson-Crick hydrogen bonds with adenosine, cytosine, thymine and uracil, but only Hoogsteen base pairing with guanine (16, 17).

Is xanthine oxidase A Metalloprotein?

Xanthine oxidase is defined as an enzyme activity (EC 1.17. 3.2). The same protein, which in humans has the HGNC approved gene symbol XDH, can also have xanthine dehydrogenase activity (EC 1.17….Xanthine oxidase.

xanthine oxidase/dehydrogenase
Identifiers
EC number	1.17.3.2
Locus	Chr. 2 p23.1
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What type of enzyme is xanthine oxidase?

Xanthine oxidase is a form of xanthine oxidoreductase, an enzyme that generates reactive oxygen species such as superoxide radicals and hydrogen peroxide when it catalyzes the oxidation of hypoxanthine to xanthine, and can further catalyze the oxidation of xanthine to uric acid.

What color is xanthine?

yellow
Xanthine derives from the Greek word “xanthos,” meaning yellow. You’re most likely to see it used to suggest a yellow tint, as in fall trees turned a xanthine orange.

Is xanthine a diuretic?

Caffeine has long been considered practically useless, so far as its diuretic action in human beings is concerned, and the term “xanthine diuretic” is therefore restricted to theobromine and theophylline, both of which are frequently employed in combination with other substances.

Is TVB n a good indicator of product quality?

Several other authors have suggested that TVB-N could be a good quality indicator for crustaceans; in Australia and Japan it is commonly used as a quality index for shrimps, for trade purposes, setting a limit of acceptability at 30 mg/100 g (Smaldone et al., 2011).

How is hypoxanthine repaired?

In Escherichia coli, the major enzyme activity that initiates the repair of hypoxanthine and xanthine is endonuclease V. Endonuclease V is an endonuclease that hydrolyzes the second phosphodiester bond 3′ to the lesion.