Plant protein hydrolysates: Preparation of defined peptide fractions promoting growth and production in animal cells cultures

A new approach was applied with the aim at producing plant protein hydrolys ates less heterogeneous and less contaminated with nonpeptide substances th an are the presently available digests. A significant reduction of nonprote in contaminants was achieved by extraction of the plant material, soy flour or wheat flour, with acetone prior to isolation of the protein. Enzymes of nonanimal origin, papain or Pronase, were used for protein hydrolysis. The components of the hydrolysates were resolved by low-pressure liquid chroma tography. Separation of peptide fractions and of remaining nonpeptide conta minants was achieved using small-pore size-exclusion chromatography matrice s, Sephadex G-15 or Biogel P-2. Individual peptide fractions, both from soy protein and from wheat gluten, varied substantially in their growth-promot ing and production-enhancing activities when tested on a mouse hybridoma cu lture in protein-free medium. The highest enhancement of viable cell densit y in batch cultures was 180% of control, and the highest enhancement of fin al immunoglobulin concentration was more than 230% of control. The existenc e of marked differences in activity of individual peptide fractions leads t o a suggestion that the hydrolysates may provide peptides exerting specific positive effects on cultured animal cells.