New alpha-amylase and trypsin inhibitors among the CM-proteins of barley (Hordeum vulgare).

Barley CM-proteins are a group of at least five salt-soluble components (CMa-e) that can be selectively extracted from endosperm with chloroform/methanol mixtures. N-terminal sequences of proteins CMa, CMb and CMc have been determined and found to be homologous to those previously determined for CMd and CMe, an observation which confirms that their structural genes are members of a dispersed multi-gene family. The purified CM-proteins were tested against trypsin and against alpha-amylases from saliva, pancreas, Aspergillus oryzae, Tenebrio molitor and barley. Besides CMe, which was known to be a trypsin inhibitor, CMc also showed antitrypsin activity, whereas CMa was specifically active against the alpha-amylase from T. molitor and no inhibitory activity was found for proteins CMb and CMd. The evolutionary implications of these findings are discussed.