Valyl-Alanyl-Prolyl-Glycine Serves as a Quantitative Marker for Human Elastins

Thermolysin digests of human elastins were examined for elastin peptide markers as determined by HPLC followed by amino acid sequencing of promising peaks. The tetrapeptide VAPG was found to occur in the early portion of the chromatogram highly fashion. The peptide appears to be significantly amplified, when compared with the other peptides, in that it is derived from the hexapeptide repeat in e1astin, VGVAPG, which repeats itself in two three-pieceegments in the c-terminal portion of the tropoelastin molecule. VAPG serves as a highly reliable quantitative measure for human elastins, allowing sensitivities to less than a microgram. Thus, it is a significantly more accurate measure than other existing methods. Precision also appears to be enhanced because of the directness of the measurements. The use of VAPG as a quantitative marker for human elastin has clinical application in the study of elastin-based connective tissue diseases.