Myoglobin, apomyoglobin, S-carboxymethyl bovine serum albumin, soluble S-carboxymethyl high-sulphur (SCMKB) and low-sulphur (SCMKA) proteins from wool, and also insoluble wool fibres have been subjected to ultrasonic irradiation in formic acid and the modified proteins studied by gel-permeation chromatography and other methods.