Biochemical Model Reactions on the Prooxidative Activity of Homocysteine

The sulfur amino acid homocysteine has recently been addressed as marker for vessel damaging and atherosclerotic dispositions. The atherogenic index has been correlated with the one of cholesterol and is significantly higher in cholesterinemic as compared to normal lipidemic persons. In the present communication biochemical model reactions are presented indicating the prooxidative activity of homocysteine where a cooperative effect with the transition-metals copper and iron is indicated.

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Met31p and Met32p, two related zinc finger proteins, are involved in transcriptional regulation of yeast sulfur amino acid metabolism.

Molecular and Cellular Biology ◽

10.1128/mcb.17.7.3640 ◽

1997 ◽

Vol 17 (7) ◽

pp. 3640-3648 ◽

Cited By ~ 84

Author(s):

P L Blaiseau ◽

A D Isnard ◽

Y Surdin-Kerjan ◽

D Thomas

Keyword(s):

Transcriptional Regulation ◽

Amino Acid ◽

Zinc Finger ◽

Amino Acid Metabolism ◽

Acid Metabolism ◽

Dependent Manner ◽

Sulfur Amino Acid ◽

Cis Acting ◽

The One ◽

Methionine Transport

Sulfur amino acid metabolism in Saccharomyces cerevisiae is regulated by the level of intracellular S-adenosylmethionine (AdoMet). Two cis-acting elements have been previously identified within the 5' upstream regions of the structural genes of the sulfur network. The first contains the CACGTG motif and is the target of the transcription activation complex Cbflp-Met4p-Met28p. We report here the identification of two new factors, Met31p and Met32p, that recognize the second cis-acting element. Met31p was isolated through the use of the one-hybrid method, while Met32p was identified during the analysis of the yeast methionine transport system. Met31p and Met32p are highly related zinc finger-containing proteins. Both LexA-Met31p and LexA-Met32p fusion proteins activate the transcription of a LexAop-containing promoter in a Met4p-dependent manner. Northern blot analyses of cells that do not express either Met31p and/or Met32p suggest that the function of the two proteins during the transcriptional regulation of the sulfur network varies from one gene to the other. While the expression of both the MET3 and MET14 genes was shown to strictly depend upon the presence of either Met31p or Met32p, the transcription of the MET25 gene is constitutive in cells lacking both Met31p and Met32p. These results therefore emphasise the diversity of the mechanisms allowing regulation of the expression of the methionine biosynthetic genes.

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Homocysteine-Induced Oxidative Damage: Mechanisms and Possible Roles in Neurodegenerative and Atherogenic Processes

Zeitschrift für Naturforschung C ◽

10.1515/znc-1995-9-1017 ◽

1995 ◽

Vol 50 (9-10) ◽

pp. 699-707 ◽

Cited By ~ 22

Author(s):

Elke Schlüssel ◽

Gudrun Preibisch ◽

S. Piitter ◽

E. F. Elstner

Keyword(s):

Amino Acid ◽

Oxidative Damage ◽

Blood Plasma ◽

Low Density Lipoprotein ◽

Plasma Concentrations ◽

Density Lipoprotein ◽

Low Density ◽

Biochemical Model ◽

Oxidation Of Methionine ◽

Model Reactions

Abstract Increased blood plasma concentrations of the sulphur amino acid homocysteine (“homocysteinemia”) have been brought into context with neurodegenerative and arteriosclerotic symptoms and diseases. We recently reported on biochemical model reactions on the prooxidative activity of hom ocysteine including the desactivation of Na+/K+-ATPases and hemolysis of erythrocytes (Preibisch et al., 1993). In this communication we extend our model reactions including the oxidation of methionine, metabolization of pyridoxalphosphate and dihydroxyphenylalanine, desactivations of transaminases and peroxidation of low density lipoprotein

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