Protein fractionation, nucleic acids, and enzymatic activity of cytoplasmic extracts from the intestinal mucosa of sheep

Abstract

A method was designed to separate and study the cytoplasmic proteins of the intestinal mucosa of sheep. Specimens of mucosa from healthy sheep were extracted and analyzed for protein and nucleic acid content, and for selected enzyme activities. The proteins of this extract were separated by DEAE-cellulose chromatography. Samples of ulcerated mucosa were also extracted and analyzed for protein and nucleic acid content. Extracts from healthy mucosa contained more protein (71 ± 7 versus 52 ± 8 mg/ml) and less nucleic acid (8.5 ± 3 versus 14 ± 3 mg/ml) than extracts from ulcerated mucosa. The enzyme assay on healthy extracts showed that protease, amylase, alkaline phosphatase, transaminase, and lactase activity were present. Fractionation of the extracted proteins on DEAE-cellulose, using a Tris-HCl buffer (0.05 m, pH 9.0) and a sodium chloride gradient of 0.0–0.04 m, yielded 10 major protein fractions, of which 6 were eluted at less than 0.1 m NaCl. This system is useful for investigating changes in cytoplasmic proteins caused by drugs and diseases affecting the intestinal mucosa.