Homocysteine is a protein amino acid in humans: Implications for homocysteine-linked disease

Hieronim Jakubowski

doi:https://doi.org/10.1074/jbc.C200267200

Homocysteine is a protein amino acid in humans: Implications for homocysteine-linked disease

Hieronim Jakubowski

New Jersey Medical School (NJMS), Microbiology

Rutgers, The State University

Research output: Contribution to journal › Article › peer-review

162 Scopus citations

Abstract

Homocysteine is thought to be a non-protein amino acid. However, in vitro studies suggest that homocysteine is likely to be incorporated by indirect mechanisms into proteins in living organisms. Here I show that homocysteine is a protein amino acid in humans. Homocysteine bound by amide or peptide linkages (HcyN-protein) is present in human hemoglobin, serum albumin, and γ-globulins. 1 molecule of homocysteine per 1000 or 1670 molecules of methionine was present in hemoglobin or albumin, respectively. Other proteins, such as low density lipoprotein, high density lipoprotein, transferrin, antitrypsin, and fibrinogen, contained lower amounts of Hcy-N-protein. In human plasma, levels of Hcy-N-protein represented from 0.3 to 23% of total homocysteine. Thus, Hcy-N-protein is a significant component of homocysteine metabolism in humans, possibly contributing to adverse effects of homocysteine on human cells.

Original language	American English
Pages (from-to)	30425-30428
Number of pages	4
Journal	Journal of Biological Chemistry
Volume	277
Issue number	34
DOIs	https://doi.org/10.1074/jbc.C200267200
State	Published - Aug 23 2002

ASJC Scopus subject areas

Biochemistry
Molecular Biology
Cell Biology

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title = "Homocysteine is a protein amino acid in humans: Implications for homocysteine-linked disease",

abstract = "Homocysteine is thought to be a non-protein amino acid. However, in vitro studies suggest that homocysteine is likely to be incorporated by indirect mechanisms into proteins in living organisms. Here I show that homocysteine is a protein amino acid in humans. Homocysteine bound by amide or peptide linkages (HcyN-protein) is present in human hemoglobin, serum albumin, and γ-globulins. 1 molecule of homocysteine per 1000 or 1670 molecules of methionine was present in hemoglobin or albumin, respectively. Other proteins, such as low density lipoprotein, high density lipoprotein, transferrin, antitrypsin, and fibrinogen, contained lower amounts of Hcy-N-protein. In human plasma, levels of Hcy-N-protein represented from 0.3 to 23% of total homocysteine. Thus, Hcy-N-protein is a significant component of homocysteine metabolism in humans, possibly contributing to adverse effects of homocysteine on human cells.",

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T1 - Homocysteine is a protein amino acid in humans

T2 - Implications for homocysteine-linked disease

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N2 - Homocysteine is thought to be a non-protein amino acid. However, in vitro studies suggest that homocysteine is likely to be incorporated by indirect mechanisms into proteins in living organisms. Here I show that homocysteine is a protein amino acid in humans. Homocysteine bound by amide or peptide linkages (HcyN-protein) is present in human hemoglobin, serum albumin, and γ-globulins. 1 molecule of homocysteine per 1000 or 1670 molecules of methionine was present in hemoglobin or albumin, respectively. Other proteins, such as low density lipoprotein, high density lipoprotein, transferrin, antitrypsin, and fibrinogen, contained lower amounts of Hcy-N-protein. In human plasma, levels of Hcy-N-protein represented from 0.3 to 23% of total homocysteine. Thus, Hcy-N-protein is a significant component of homocysteine metabolism in humans, possibly contributing to adverse effects of homocysteine on human cells.

AB - Homocysteine is thought to be a non-protein amino acid. However, in vitro studies suggest that homocysteine is likely to be incorporated by indirect mechanisms into proteins in living organisms. Here I show that homocysteine is a protein amino acid in humans. Homocysteine bound by amide or peptide linkages (HcyN-protein) is present in human hemoglobin, serum albumin, and γ-globulins. 1 molecule of homocysteine per 1000 or 1670 molecules of methionine was present in hemoglobin or albumin, respectively. Other proteins, such as low density lipoprotein, high density lipoprotein, transferrin, antitrypsin, and fibrinogen, contained lower amounts of Hcy-N-protein. In human plasma, levels of Hcy-N-protein represented from 0.3 to 23% of total homocysteine. Thus, Hcy-N-protein is a significant component of homocysteine metabolism in humans, possibly contributing to adverse effects of homocysteine on human cells.

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Homocysteine is a protein amino acid in humans: Implications for homocysteine-linked disease

Abstract

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