Comparative biochemistry of serum albumin. A serum albumin-like protein from carp, cyprinus carpio

Abstract

1. 1. The protein component in carp serum which has the disc gel electrophoretic mobility corresponding to human serum albumin has been characterized. This component was purified and identified as an albumin-like protein. 2. 2. The purification from carp, Cyprinus carpio, was performed using Sephadex G-100 gel filtration and DEAE cellulose column chromatography and isoelectric focusing. The isolated protein was homogenous according to various electrophoreses and an immunological method. 3. 3. The molecular weight was approximately 59,000 and the isoelectric point was pH 5·2. Less than one sulfhydryl group per molecule was detected by titration with 5,5′-dithiobis(2-nitrobenzoic acid). 4. 4. The fastest moving component of carp serum in cellulose acetate electrophoresis gives a color with Schiff's reagent. The albumin-like protein in carp serum is found in the cathodic site of the fastest-moving component and is one of the proteins which has high solubility as judged by saltingout with sodium sulfate and by extraction with acidified organic solvent.