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Tyrosine

About: Tyrosine is a(n) research topic. Over the lifetime, 15918 publication(s) have been published within this topic receiving 706571 citation(s). The topic is also known as: Tyr & (2S)-2-amino-3-(4-hydroxyphenyl)propanoic acid.
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Journal ArticleDOI
Abstract: The article summarizes research into the existing methods for the quantitative determination of tyrosine and tryptophane in proteins. Limitations to the accuracy of the Folin-Looney method (reaction of a phosphotungstic phosphomolybdic acid in a phenol solution, evaluated using colorimetry) have been solved by an improved method detailed in the text. The hydrolysis of proteinaceous material to allow chemical analysis of tryptophane has also been improved; the method is based on digestion with sodium hydroxide for 18-20 hours, followed by rapid neutralization and acidification with sulfuric acid. A more accurate test for tyrosine based on Millon's reaction has been developed; acidified mercuric sulfate solution is used to dissolve precipitated tyrosine and sodium nitrite is added to produce the colored product which is assessed colorimetrically. Two types of casein analyzed by these methods contained 1.4% tryptophane and 6.37-6.55% tyrosine. Tryptophane and tyrosine content of various materials were: casein 1.4%, 6.4-6.6%; egg albumin 1.3%, 4.0%; edestin 1.5%, 4.5%; gliadin 0.84%, 3.1%; zein 0.17%, 5.9%. A method for preparation of the pure mercuric sulfate reagent is described.

2,368 citations


Journal ArticleDOI
TL;DR: It is inferred that pp60src is a novel protein kinase and that the modification of proteins via the phosphorylation of tyrosine is essential to the malignant transformation of cells by Rous sarcoma virus.
Abstract: The protein kinase activity associated with pp60src, the transforming protein of Rous sarcoma virus, was found to phosphorylate tyrosine when assayed in an immunoprecipitate. Despite the fact that a protein kinase with this activity has not been described before, several observations suggest that pp60src also phosphorylates tyrosine in vivo. First, chicken cells transformed by Rous sarcoma virus contain as much as 8-fold more phosphotyrosine than do uninfected cells. Second, phosphotyrosine is present in pp60src itself, at one of the two sites of phosphorylation. Third, phosphotyrosine is present in the 50,000-dalton phosphoprotein that coprecipitates with pp60src extracted from transformed chicken cells. We infer from these observations that pp60src is a novel protein kinase and that the modification of proteins via the phosphorylation of tyrosine is essential to the malignant transformation of cells by Rous sarcoma virus. pp60sarc, the closely related cellular homologue of viral pp60src, is present in all vertebrate cells. This normal cellular protein, obtained from both chicken and human cells, also phosphorylated tyrosine when assayed in an immunoprecipitate. This is additional evidence of the functional similarity of these structurally related proteins and demonstrates that all uninfected vertebrate cells contain at least one protein kinase that phosphorylates tyrosine.

2,045 citations


Journal ArticleDOI
TL;DR: It has now been possible to demonstrate that brain, adrenal medulla, and sympathetically innervated tissues contain a specific hydroxylase that catalyzes the conversion of L-tyrosine to dopa.
Abstract: After demonstration of the decarboxylation of 3,4-dihydroxyphenylalanine (dopa)’ to dopamine (I), the pathway for biosynthesis of norepinephrine shown in Fig. 1 was proposed. Although evidence for this pathway was well established by isot,opic procedures (2, 3), it was not until 1960 that Levin, Levenberg, and Kaufman (4) succeeded in isolating and characterizing the third enzyme in the series, dopamine-B-oxidase (@hydroxylase). The enzyme responsible for converting tyrosine to dopa has, however, proved elusive. The enzyme tyrosinase was considered in this role, but no evidence for it could be obtained in sympathetically innervated tissues. Reports of the enzymatic conversion of tyrosine to catecholamines by tissue slices and minces have generally been unconvincing owing to large and variable blanks with boiled preparations (5, 6). It has now been possible to demonstrate that brain, adrenal medulla, and sympathetically innervated tissues contain a specific hydroxylase that catalyzes the conversion of L-tyrosine to dopa. A short report on the properties of a particle-bound preparation from brain has already appeared (7). The present communication describes the isolation, purification, and charact#erization of a soluble tyrosine hydroxylase from beef adrenal medulla. The soluble tyrosine hydroxylase requires for activity tetrahydropteridine derivatives comparable to those previously observed for phenylalanine hydroxylase (8).

1,989 citations


Journal ArticleDOI

1,835 citations


Journal ArticleDOI
17 May 1991-Cell
TL;DR: Cl cloning and characterization of two ERK1-related kinases, ERK2 and ERK3, are described and evidence suggesting that there are additional ERK family members is provided, which may serve as intermediates that depend on tyrosine phosphorylation to activate serine/threonineosphorylation cascades.
Abstract: We recently described the purification and cloning of extracellular signal-regulated kinase 1 (ERK1), which appears to play a pivotal role in converting tyrosine phosphorylation into the serine/threonine phosphorylations that regulate downstream events. We now describe cloning and characterization of two ERK1-related kinases, ERK2 and ERK3, and provide evidence suggesting that there are additional ERK family members. At least two of the ERKs are activated in response to growth factors; their activations correlate with tyrosine phophorylation, but also depend on additional modifications. Transcripts corresponding to the three cloned ERKs are distinctly regulated both in vivo and in a differentiating cell line. Thus, this family of kinases may serve as intermediates that depend on tyrosine phosphorylation to activate serine/threonine phosphorylation cascades. Individual family members may mediate responses in different developmental stages, in different cell types, or following exposure to different extracellular signals.

1,808 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20221
2021187
2020239
2019217
2018211
2017206

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Topic's top 5 most impactful authors

Richard J. Wurtman

65 papers, 4K citations

Toshiharu Nagatsu

26 papers, 2.6K citations

Paul F. Fitzpatrick

23 papers, 1K citations

Seymour Kaufman

19 papers, 879 citations

André Veillette

18 papers, 1.4K citations