[Modification of proteins by reaction with carbonyl compounds]

The authors deal with chemical and physico-chemical changes in casein and vegetable globulins after reaction with aldehydes or acylation with carboxylic acid chlorides and anhydrides. The stepwise blocking of the alpha- and epsilon-amino groups leads to modified proteins with lowered isoelectric points and changes in the solubility and precipitability characteristics and in the electrophoretic behaviour. There are relationships between the relative nutritive value (as determined by means of Tetrahymena pyriformis) and the blocking of lysine. On acylation of the protein, the relative nutritive value is influenced by the length of the acyl residue and the kind of modification (N or O-blocking).