DEGRADATION OF ANTIFLAMMIN 2 UNDER ACIDIC CONDITIONS

Antiflammin 2 (HDMNKVLDL, AF2) is a synthetic peptide derived from the region of highest sequence similarity of lipocortin I and uteroglobin , and is a potent antiinflammatory agent without any known side effect s of corticosteroids. The antiinflammatoly activity of AF2 has been de monstrated, but is not reproducible between laboratories. It has been suggested that the chemical instability of this peptide is responsible for the loss of activity. The degradation of AF2 in aqueous solutions at a pH range of 3 to 10 has been reported. In this study, the degrad ation of AF2 at acidic pHs was monitored by reversed-phase HPLC. The r eactions were studied as functions of buffer concentration and tempera ture. The rates of loss of AF2 followed apparent pseudo-first-order ki netics. Several products were isolated and identified by fast atom bom bardment mass spectroscopy and tandem mass spectroscopy, and were the result of C- and N-terminus hydrolyses of aspartyl peptide bonds in AF 2. The peptide bonds at C-termini of the aspartyl residues were most s usceptible to hydrolysis, resulting in the formation of major degradat ion products, HDMNKVLD, MNKVLDL, and MNKVLD. The minor products from t he N-terminus hydrolysis were HDMNKVL and MNKVL and formed at much slo wer rates.