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Aminomalonic acid: identification in Escherichia coli and atherosclerotic plaque
Abstract:
Aminomalonic acid (Ama) has been isolated from proteins of Escherichia coli and human atherosclerotic plaque. The presence of Ama has important biological implications because the malonic acid moiety potentially imparts calcium binding properties to protein. Ama was obtained by anaerobic alkaline hydrolysis and identified by chromatographic behavior, quantitative acid-mediated decarboxylation to glycine, and unambiguous gas chromatographic/mass spectral detection. The chromatographic, chemical, and mass spectral properties of naturally occurring Ama were identical to those of the synthetic compound. Amino acid analysis and GC/mass spectrometry also revealed the presence of beta-carboxyaspartic acid and gamma-carboxyglutamic acid in the base hydrolysate of human atherosclerotic plaque. The ratio of Ama to beta-carboxyaspartic acid to gamma-carboxyglutamic acid was 20:1:10, and the quantity of Ama per 1,000 glycine residues was 0.2. Ama is a relatively unstable, minor amino acid in complex structures such as bacteria or tissues. This may explain why it has escaped detection previously, despite intensive investigation.
Insights
Aminomalonic acid (Ama) was identified in E. coli and human plaque proteins. Its presence suggests potential calcium-binding roles in biological structures, explaining its prior undetected status.
Area of Science:
- Biochemistry
- Proteomics
- Analytical Chemistry
Background:
- Aminomalonic acid (Ama) is a non-proteinogenic amino acid.
- Proteins from Escherichia coli and human atherosclerotic plaque were analyzed.
- The malonic acid moiety of Ama may confer calcium-binding properties to proteins.
Purpose of the Study:
- To isolate and identify Aminomalonic acid (Ama) from biological sources.
- To investigate the biological implications of Ama's presence in proteins.
- To characterize Ama and compare it with synthetic standards.
Main Methods:
- Proteins were subjected to anaerobic alkaline hydrolysis.
- Ama was identified using chromatographic behavior, acid-mediated decarboxylation to glycine, and gas chromatography/mass spectrometry (GC/MS).
- Amino acid analysis and GC/MS were used to detect other related amino acids.
Main Results:
- Aminomalonic acid (Ama) was successfully isolated and identified from E. coli and human atherosclerotic plaque proteins.
- The naturally occurring Ama exhibited identical properties to the synthetic compound.
- Beta-carboxyaspartic acid and gamma-carboxyglutamic acid were also detected in human plaque hydrolysates.
Conclusions:
- Aminomalonic acid (Ama) is a naturally occurring amino acid in bacteria and human tissues.
- Ama's instability and low abundance may explain its previous undetected status.
- The identification of Ama has significant implications for understanding protein structure and function, particularly in calcium binding.