Determination of phospholipase A2 activity by a colorimetric assay using a pH indicator

Abstract A. Lōbo de Araujo and F. Radvanyi . Determination of phospholipase A 2 activity by a colorimetric assay using a pH indicator. Toxicon 25, 1181 – 1188, 1987. — We have set up an assay of phospholipase A 2 by a spectrophotometric method, based on the pH change due to the liberation of fatty acids. Among the pH indicators used, phenol red was found to be one of the most sensitive. The activities of different phospholipases A 2 from venom and from porcine pancreas were measured by this assay. The results are comparable to those obtained by the pH stat method. This very simple test is rapid, sensitive and especially useful for assaying numerous samples. For quantitative results in absolute units it must be considered that the pH indicator may inhibit some phospholipases.