Protein deamidase from germinating wheat grains.

A new enzyme catalyzing the deamidation of seed storage proteins was found in germinating wheat grains and was partially purified. It also acts on egg lysozyme, horse hemoglobin and reduced RNAse, glutamine and Gly-L-Gln-L-Tyr. No activity was observed when using ovalbumin, serum albumin, RNAse, insulin, asparagine and an asparagine-containing peptide. Only glutaminyl residues appear to be deamidated by this enzyme. It differs from transglutaminase and proved to be a true protein deamidase.