Tyrosine Terms Links

As with many neurons (e.g. NA) there are presynaptic autoreceptors on the terminals of dopamine neurons whose activation attenuate DA release. Although most of these receptors appear to be of the D2 type, as found postsynaptically, D3 receptors are also found. It is possible that in addition to the short-term control of transmitter release they may also be linked directly to the control of the synthesising enzyme tyrosine hydroxylase. It seems that autoreceptors are more common on the terminals of nerves in the nigrostriatal (and possibly mesolimbic) than mesocortical pathway. 

X 10 M s and was 3.1 x 10 M s" at 25°C, pH 7.0 and ionic strength of 1.0 . Kinetic data was interpreted in terms of a mechanism of electron transfer from chromium(II) involving attack of Cr(II) adjacent to the Fe(III) center Analysis of the one-to-one chromium(III) cytochrome c complex revealed that the chromium(III) cross-linked two peptide fragments located in the heme.crevice by binding to tyrosine 67 and asparagine 52 The chromium(III) bound to reduced cytochrome c did not affect the ability of the protein to be reoxidized with ferricyanide and then to be reduced with dithionite . The chromium complex was oxidized by cytochrome oxidase at the same rate as the untreated ferrocytochrome c, however, the rate of reduction of the chromium complex by bovine heart submitochondrial particles was slower than that of untreated ferricytochrome c Thus, the binding of chromium(III) to cytochrome c appears to selectively inhibit its function in certain electron transfer reactions. 

Melanins are black, brown or red, polymerized, insoluble amorphous pigments derived from different groups of phenolics. The term eumelanins is used to describe black tyrosine polymers, which are found mainly in the animal kingdom. Phaeomelanins are the yellow to red tyrosine-derived pigments in hair and feathers of animals. Both types of pigments contain indole derivatives as fundamental moieties. Melanins are closely linked to proteins. Their molecular weight is not determinable. They are extraordinarily stable and were isolated even from 150-million-year-old fossils. 

Another synthetic concept of polyamides includes the term pseudo-poly(amino acids). In this family of polymers belong naturally occurring amino acids linked by non-amide bonds. Tyrosine, serine and hydroxyproline-derived polymers with ester and iminocarbonate bonds in the chain have been investigated [446],... 

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