Tyrosine mammalian

Phenylalanine Hydroxylase (EC 1.14.16.1). In arene hydroxylation of phenylalanine to produce tyrosine, mammalian phenylalanine hydroxylase (PAH) requires nonheme iron and tetrahydropterin cofactor. The role of the metal is... 

II cleaves the two complementary strands of DNA four base pairs apart and the resulting 5 -phosphoryl groups become covalently linked to a pair of tyrosine groups, one in each half of the dimeric topoisomerase II enzyme. Several groups of drugs are known that selectively inhibit topoisomerases in bacteria (quino-lones) or mammalian cells (etoposide, tenoposide). Quinolones are used to treat bacterial infections inhibitors of mammalian topoisomerases are cytostatic drugs used for the treatment of cancer. 

Devary, Y., Gottlieb, R.A., Smeal, T., Karin, M. (1992). The mammalian ultraviolet response is triggered by activation of Src tyrosine kinases. Cell 71, 1081-1091. 

Tyramine is produced by decarboxylation of tyrosine and is present in the CNS in higher (threefold) concentrations than m-tyramine, the hydroxylated derivative of phenylethylamine. In the periphery / -tyramine is easily hydroxylated to octopamine, which has some direct effects on ai adrenoceptors, unlike tyramine which functions by releasing NA. When tested on central neurons tyramine always produces the same effects as NA but they are slower and less marked, implying an indirect action. By contrast octopamine often produces the opposite effect to NA and it is probable that octopamine may have a functional role in the invertebrate CNS where it is found in higher concentrations (5pg/g) than in the mammalian brain (0.5ng/g). Neither tyramine nor octopamine have distinct behavioural effects, unlike phenylethylamine,... 

MARKOVITS J, LINASSIER C, FOSSE P, COUPRIE J, PIERRE J, JACQUEMIN-SABLON A, SAUCIER J M, LE PECQ J B, LARSEN A K (1989) Inhibitory effects of the tyrosine kinase inhibitor genistein on mammalian DNA topoisomerase II. Cancer Res. 49 5111-17. 

Ben-David, Y., Letwin, K., Tannock, L., Bernstein, A., and Pawson, T. (1991). A mammalian protein kinase with potential for serine/threonine and tyrosine phosphorylation is related to cell cycle regulators. EMBO J. 10 317-325. 

Protein kinases differ in their cellular and subcellular distribution, substrate specificity and regulation. These properties determine the functional roles played by the very large number of protein kinases that have been found in mammalian tissues, most of which are known to be expressed in neurons [3]. The major classes of protein serine-threonine kinase in the brain, listed in Table 23-1, are covered in this chapter. The major classes of protein tyrosine kinases in the brain are discussed in Chapter 24. 

The enantiomeric purity of protected amino acids used in peptide synthesis can be determined by pre-column partial deprotection followed by derivatization with Marfey s reagent (116). The Marfey diastereoisomers can be easily resolved and determined by RP-HPLC using an ODS-Hypersil column288. Fifteen amino acids collected from mammalian tissues were derivatized with Marfey s reagent and subjected to two-dimensional TLC. Each individual spot (enantiomeric mixture of a diasteroisomer) was then resolved by RP-HPLC. Except for tyrosine (46) and histidine (117), subnanomole quantities of enantiomers could be analyzed289,290. 

Inhibits serine proteases such as trypsin and chymotrypsin. Also inhibits cysteine proteases (reversible by reduced thiols) and mammalian acetylcholinesterase Inhibits ATPase, alkaline phosphatase and tyrosine phosphatase Reagent for maintaining -SH groups in the reduced state. Effective for reducing protein disulfide bonds prior to SDS-PAGE... 

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