Measurement of homoarginine in human and mouse plasma by LC-MS/MS and ELISA: a comparison and a biological application.

Abstract

Homoarginine (hArg) is a non-essential amino acid that was identified as a risk marker for cardiovascular disease. Several analytical methods have been described for the quantification of hArg in biological samples. The aim of this study was to compare a liquid chromatography-tandem mass spectrometric (LC-MS/MS) approach with a commercially available enzyme-linked immunosorbent assay (ELISA). Determination of hArg concentrations in ELISA calibration standards measured by both methods revealed a correlation coefficient r (2) of 0.99, for LC-MS/MS calibrators r (2) was 0.997. However, linear regression analysis between the two assays for hArg concentrations in human plasma samples revealed a correlation coefficient r (2) of 0.78. Plasma concentrations obtained from LC-MS/MS are on average 29 % higher than those by ELISA. We investigated the hArg-isobaric N (ε)-trimethyllysine as potential source for the higher observed values, but evaluation of mass spectra indicated that N (ε)-trimethyllysine did not interfere with hArg quantification in our LC-MS/MS method. Both quantification methods were applied to measure hArg in (1) a case-control study of acute coronary syndrome and (2) L-arginine:glycine amidinotransferase-deficient mice. Our LC-MS/MS and the commercially available ELISA assay are suitable for hArg measurement in human and mouse plasma, but different reference values for each method need to be considered.

• Authors: Kathrin Cordts, Dorothee Atzler, Vazhma Qaderi, Karsten Sydow, Rainer H Böger, Chi-Un Choe, Edzard Schwedhelm
• Journal: Amino acids (Amino Acids) Vol. 47 Issue 9 Pg. 2015-22 (Sep 2015) ISSN: 1438-2199 [Electronic] Austria
• PMID: 26159673 (Publication Type: Comparative Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Homoarginine

Topics

• Animals
• Enzyme-Linked Immunosorbent Assay (methods)
• Female
• Homoarginine (blood, genetics)
• Humans
• Mass Spectrometry (methods)
• Mice
• Mice, Knockout
• Sensitivity and Specificity