Changes of Nucleic Acids in the Preparation Process of Cell Protein Isolates from Yeast (Saccharomyces cerevisisae)

Abstract

Cell protein isolates were prepared from yeast (S. cerevisiae) by alkali-extraction followed by acid precipitation. The relationships between alkali-treatment and nucleic acid contents in cell protein isolates were examined.
The isolate which was precipitated at pH 4.5 following extraction with 0.20 N NaOH at 80°C contained small amounts (less than 1% of the isolate) of nucleic acids. However, the content of nucleotides in the isolate which was precipitated at pH 4.5 following extraction with 0.20 N NaOH at 37°C was 9.13% of the product. Treatment by washing or dialysis of the isolate had little effect in removing the nucleotides in the isolate.
This finding was explained by the interaction of nucleotide to cell protein isolate. The binding energy was measured by Hummel's method.