The enzymatic degradation of urocanic acid.

Enzymatic production of urocanic acid by Achromobacter liquidum.

To develop an efficient method for the production of urocanic acid, optimal conditions for the production of microbial L-histidine ammonia lyase and for the conversion of L-histidine to urocanic acid by this enzyme were studied. A number of microorganisms were screened to test their ability to form and accumulate urocanic acid from L-histidine. Achromobacter liquidum was selected as the best or...

The Mammalian Metabolism of L-Histidine

The major pathway of histidine metabolism in animals and bacteria other than incorporation into protein involves first deamination to urocanic acid, then the anaerobic addition of water to form an intermediate generally considered to be 4(5)imidazolone-5(4)-propionic acid (1, 2). Finally, the ring is split enzymatically to ~formiminoglutamic acid (3) which is converted to free cglutamic acid by...

Computational study of three dimensional potential energy surfaces in intermolecular hydrogen bonding of cis-urocanic acid

Reversible stepwise mechanism involving a carbanion intermediate in the elimination of ammonia from L-histidine catalyzed by histidine ammonia-lyase.

L-Histidine labeled with deuterium at the C-5' position of the imidazole ring, L-[5'-2H]histidine (His-5'-D), was used as a probe for investigating a stepwise reversible mechanism via a carbanion intermediate in the elimination of ammonia catalyzed by histidine ammonia-lyase (EC 4.3.1.3). The labeled L-histidine (His-5'-D) (2.45 mM) was incubated with histidine ammonia-lyase (200 units) from Ps...

Urocanic acid and immunosuppression.

Urocanic acid, a molecule found at high concentration in the stratum corneum, acts as a photoreceptor for UV-light, isomerizing from the naturally occurring trans-form to the cis-form. It has been proposed that cis-urocanic acid may mediate the transient alteration in immune surveillance resulting in immunosuppression induced after UV-irradiation, by interacting with immune cells locally and/or...