Process for purifying low molecular weight proteins from tissue in situ

A process for isolating low molecular weight peptides from tissue in situ is described. The process comprises the steps of: Homogenizing the tissue, b) mixing the homogenized tissue with an organic solvent such as ethanol or 70% ethanol to form a fully-wetted slurry; c) standing or agitating the slurry to denature the proteins in situ within the tissue; d) removing the solvent from the tissue; e) mixing the organic solvent-treated tissue of step d) with a sufficient volume of water or an aqueous solution to extract the peptides, and f) separating a liquid extract from the tissue residue of step e) to obtain an aqueous solution containing the low molecular weight peptide fraction removed from the tissue wherein the mixing is performed below 30oC.