Determination of protein-incorporated methylated arginine reference values in healthy subjects whole blood and evaluation of factors affecting protein methylation.

OBJECTIVES: Protein arginine methylation is a post-translational modification involved in the regulation of signal transduction, RNA export, and cell proliferation. Reference values of arginine methylation of whole blood proteome remain to be determined. DESIGN AND METHODS: Asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA) and monomethylarginine (MMA) incorporated in whole blood protein and methionine, cysteine and homocysteine plasma levels from 134 healthy subjects were measured by capillary electrophoresis.
RESULTS: The mean protein-incorporated concentration of the selected population was 4.11+/-0.77 nmol/mg protein for ADMA; 1.66+/-0.42 nmol/mg protein for SDMA and 4.31+/-1.17 nmol/mg protein for MMA. Multiple correlation analysis showed that plasma Hcy was positively related to incorporated protein ADMA (P=0.002) and MMA (P=0.049).
CONCLUSIONS: The study was able to define a reference value for protein-incorporated ADMA, SDMA and MMA levels and found a positive association between protein-incorporated ADMA and plasma homocysteine.