pteridine

Pteridine is a chemical compound composed of fused pyrimidine and pyrazine rings.

A pteridine is also a group of heterocyclic compounds containing a wide variety of substitutions on this structure.

Cyanopterin is a glycosylated version of pteridine of unknown function in cyanobacteria.

It is the end product of a non-conjugated pteridine compound and inhibits the growth of lymphocytes produced by concanavalin.

Pterin is a heterocyclic compound composed of a pteridine ring system, with a keto group and an amino group on positions 4 and 2 respectively.

Folates are "conjugated" pterins that contain p-aminobenzoic acid and -glutamates connected to the methyl group at position 6 of the pteridine ring system.

PABA, glutamic acid, and a source of pteridine, are the building blocks from which the microbe constructs its own folic acid.

Chromatophores that contain large amounts of yellow pteridine pigments are named xanthophores; those with mainly red/orange carotenoids are termed erythrophores.

Molybdopterin is a substituted pteridine that binds molybdenum to give redox enzymes involved in biological hydroxylations, reduction of nitrate, and respiratory oxidation.

The oxygen incorporated need not be derived from O2 with reduced pteridine as one donor, and incorporation of one ato of oxygen into the other donor.

Tetrahydrobiopterin, the major unconjugated pteridine in vertebrates, is a co-factor in the hydroxylation of aromatic compounds and synthesis of nitric oxide.

However, vesicles containing pteridine and carotenoids are sometimes found in the same cell, in which case the overall colour depends on the ratio of red and yellow pigments.

Flavin (from Latin flavus, "yellow") is the common name for a group of organic compounds based on pteridine, formed by the tricyclic heteronuclear organic ring isoalloxazine.

Thus, hydride molecules are transferred from NADPH to the C6 position of the pteridine ring to reduce folic acid to THF.

The substance aminopterin, made by replacing an -OH group by an -NH 2 group on the pteridine part of folic acid, was a milestone in the history of chemotherapy.

The bright yellow eyes of the Great Horned Owl are thought to be due to the presence of the pteridine pigment xanthopterin within certain chromatophores (called xanthophores) located in the iris stroma.

It had three parts; the amino acid glutamic acid, the nitrogenous base pteridine, and a substance we have met previously,p- aminobenzoic acid (PABA), which linked the two other components together.

PheOH is one of three members of the pterin-dependent amino acid hydroxylases, a class of monooxygenase that uses tetrahydrobiopterin (BH, a pteridine cofactor) and a non-heme iron for catalysis.

This was subsequently identified as pterorhodin, a pteridine dimer that accumulates around eumelanin core, and it is also present in a variety of tree frog species from Australia and Papua New Guinea.

Axanthism is a condition common in reptiles and amphibians, in which xanthophore metabolism is affected rather than synthesis of melanin, resulting in reduction or absence of red and yellow pteridine pigments.