Tyrosine isolation

CgHiiNO. M.p. 282 C (decomp.). The naturally occurring substance is laevorotatory. It is an amino-acid isolated from various plant sources, but not found in the animal body. It is formed from tyrosine as the first stage in the oxidation of tyrosine to melanin. It is used in the treatment of Parkinson s disease. 

C-terminal lobes of the tyrosine kinase are similar to those of cyclin-depen-dent kinase described in Chapter 6 (see Figure 6.16a), while the SH2 and SH3 domains of Src and Hck have structures very similar to those of the isolated domains (see Figures 13.26 and 13.28a). 

This reaction was studied by use of tritium. The phenylalanine was labeled with tritium at the 4-position of the phenyl ring. When the product, tyrosine, was isolated, it retained much of the original radioactivity, even though the 4-position was now substituted by a... 

Hydrogen peroxide (H202) exhibits insulin-like activity in isolated cells. Like that of vanadate, this effect is thought to be mediated by inhibition of protein-tyrosine phosphatases. 

Gao and Yamaguchi, 1999c Gao and Yamaguchi, 2000 Kajiya et al., 2000 Yamagishi et at., 2001 Bone marrow cells or isolated osteoclasts Suppression of osteoclast formation by genistein is partly due to Ca signalling mechanism and partly due to inhibition of tyrosine kinase activity. 

Thus, thymine-tyrosine, thymine-aliphatic amino acid and cytosine-tyrosine links have been identified in isolated calf thymus chromatin subjected to 7-irradiation, or treated with metal ions and H2O2 (Dizdaroglu, 1991 Nackerdien et al., 1991). 

The most potent thrombin inhibitor is hirudin, originally isolated from the salivary glands of the medicinal leech Hirudo medicinalis. Its inhibition constant is in the femtomolar (10-15 M) range (57). It is a 65-amino-acid tyrosine-sulfated single-chain polypeptide. Recombinant hirudin differs from native hirudin by the absence of the sulfate group on tyrosine 63 (Tyr-63) and is referred to as desulfato hirudin. The loss of this sulfate group reduces the thrombin inhibitory potency by 10-fold. 

A murine male germ cell-assocated kinase (mak) was isolated by virtue of its weak homology to the v-ros tyrosine kinase (Matsushime et al., 1990). Although it was isolated because of its homology to a tyrosine kinase, sequence analysis revealed that it belongs to the serine/threonine... 

Biogenic amines are decarboxylated derivatives of tyrosine and tryptophan that are found in animals from simple invertebrates to mammals. These compounds are found in neural tissue, where they function as neurotransmitters, and in non-neural tissues, where they have a variety of functions. The enzymes involved in biogenic amine synthesis and many receptors for these compounds have been isolated from both invertebrate and vertebrate sources. In all cases, the individual proteins that effect biogenic amine metabolism and function show striking similarity between species, indicating that these are ancient and well-conserved pathways. 

Degradation of 5 and 57 revealed that both skeletons are built from two C6-C2 units derivable from tyrosine (81,82). Many 14C-labeled isoquinolines, which on biogenetic grounds could be possible late precursors of both alkaloids, were prepared and fed to Stephania japonica plants, after which the labeled alkaloids were isolated. Isoquinolines 59-64, lacking the... 

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