homogentisic acid

As a result, a substance called homogentisic acid builds up in the skin and other body tissues.

It is derived from the oxidative dimerization of homogentisic acid.

Treatment with nitisinone, which suppresses homogentisic acid production, is being studied.

Homogentisic acid also can build up on the heart valves, especially the mitral valve.

In healthy subjects, homogentisic acid is absent in both blood plasma and urine.

Ochronosis is the syndrome caused by the accumulation of homogentisic acid in connective tissues.

The main symptoms of alkaptonuria are due to the accumulation of homogentisic acid in tissues.

The defect was narrowed down to homogentisic acid oxidase deficiency in a study published in 1958.

Specifically, 4-hydroxyphenylpyruvate dioxygenase converts a tyrosine byproduct called 4-hydroxyphenylpyruvate to homogentisic acid.

This reduces homogentisic acid.

The darkened urine is the result of the exposure to the air of homogentisic acid that accumulates in the urine.

Homogentisic acid is a natural intermediary of the metabolism of tyrosine, an amino acid.

The build-up of homogentisic acid in the cartilage causes arthritis in about 50% of older adults with alkaptonuria.

The herbicide nitisinone inhibits 4-hydroxyphenylpyruvate dioxygenase, the enzyme that generates homogentisic acid from 4-hydroxyphenylpyruvic acid.

Additionally, 4-HPPA can be converted to homogentisic acid which is one of the precursors to ochronotic pigment.

Hepatic homogentisate 1,2-dioxygenase (coded by the HGD gene) metabolises homogentisic acid into 4-maleylacetoacetate.

Homogentisic acid (2,5-dihydroxyphenylacetic acid) is a phenolic acid found in Arbutus unedo (strawberry-tree) honey.

Homogentisate 1,2-dioxygenase (homogentisic acid oxidase, homogentisicase) is an enzyme, which catalyzes the conversion of homogentisate to 4-maleylacetoacetate.

Excessive homogentisic acid causes damage to cartilage (ochronosis, leading to osteoarthritis) and heart valves as well as precipitating as kidney stones.

Ochronosis occurs because of deposition of phenols (such as homogentisic acid and hydroquinone) as plaques in the matrix of cartilage.

As a result, homogentisic acid and its oxide, called alkapton, accumulate in the blood and are excreted in urine in large amounts (hence -uria).

Nitisinone inhibits the conversion of 4-OH phenylpyruvate to homogentisic acid by 4-OH phenylpyruvate dioxygenase, the second step in tyrosine degradation.

A distinctive characteristic of alkaptonuria is that ear wax exposed to air turns red or black (depending on diet) after several hours because of the accumulation of homogentisic acid.

People afflicted with adenine phosphoribosyltransferase deficiency may produce 2,8-dihydroxyadenine stones, alkaptonurics produce homogentisic acid stones, and iminoglycinurics produce stones of glycine, proline and hydroxyproline.

In a patient who underwent a liver transplant for an unrelated problem, alkaptonuria resolved and joint disease stabilised after the transplant, confirming that the liver is the main site of homogentisic acid production in alkaptonuria.