The picture of L-tyrosine metabolism obtained from isotope experiments and other studies on intact animals is still incomplete. Either p-hydroxyphenylpyruvate or 2:5-dihydroxyphenylalanine may be the first intermediate, since either could form the second postulated intermediate, 2:5-dihydroxyphenylpyruvate (Neubauer, 1909), and both are converted to homogentisic acid by alcaptonurics (Neuberger...

The biochemical study of homogentisic acid may be said to have begun with the work of Wolkow and Baumann (3), who demonstrated the relation of this compound to the metabolism of tyrosine. The intervening years have seen much effort expended on studies of the pathway of formation of homogentisic acid, but little on its further metabolism beyond the early discovery that it gives rise to ketone bo...

Alkaptonuric ochronosis is a rare autosomal recessive metabolic disorder resulting in a deficiency of homogentisic acid oxidase (alkaptonuria). Ultimately, this enzyme deficiency enables homogentisic acid to accumulate, become polymerized, and be systemically deposited within various tissues of the body (ochronosis). As the disease progresses, tissue deposition of polymerized homogentisic acid ...

Tocopherols are important antioxidants in lipophilic environments. They are synthesized by plants and some photosynthetic bacteria. Recent efforts to analyze and engineer tocopherol biosynthesis led to the identification of Synechocystis sp. strain PCC 6803 as a well-characterized model system. To facilitate the identification of the rate-limiting step(s) in the tocopherol biosynthetic pathway ...

Alkaptonuria is an autosomal recessive metabolic disorder characterized by joints and spine involvement, ochronosis and presence of homogentisic acid in urine and its deposition in cartilage, intervertebral disc and other connective tissues, leading to disabling arthritis in elderly individual.

Alkaptonuria is disorder of tyrosine metabolism due to deficiency of homogentisic oxidase characterized by excretion of homogentisic acid in urine, deposition of oxidized homogensitate pigments in connective tissues and articular cartilages (ochronosis). The result is dark pigmentation and weakening of the tissues resulting in chronic inflammation and osteoarthritis. Management of alkaptonuric ...