Catalytic properties of serum albumin

In this work it has been observed that human blood plasma is able to catalyse the reaction between tert.butyl hydroperoxide and 2-nitro-5-mercaptobenzoic acid. The purification of a proteic fraction responsible for this activity indicated it is due to plasma albumin; this is also demonstrated using various purified commercial albumins. We have determined the Vmax and the Km of the reaction and the effect of some substances of pharmacological or physiological importance on the same reaction. Some antiinflammatory non-steroidal drugs showed an inhibitory effect on the phenomenon, similar to that of endogenous substances such as fatty acids, bilirubin and arachidonic acid. The ability of other physiological substances such as cytochrome c, hemoglobin and hemin to catalyze the same reaction has also been observed.