engleski

Electrophoretic patterns of barely grain proteins and aminopeptidase activities in germination

Barley cultivars characterization and discrimination is an important issue for brewing industry and plant breeding. Several approaches including analysis of protein and enzyme activities have been used for these purposes. Among known enzymes, not much studied aminopeptidases (AP) could affect malt properties and consequently the quality of beer. Using amino acid-2-naphthylamides (2-NA) as substrates we have investigated the presence of various APs in barley grains and changes of their activities at different germination phases. Also total protein content and protein SDS-PAGE patterns were determined. In this preliminary study a standard Angora strain and two strains developed at the Agricultural Institute in Osijek, Rodnik and Barun, were compared. In all three cultivars APs were present, those preferring Phe, Leu, Met and Arg being dominant. Specific activities of water-soluble proteins have shown an increase during 24 hours of steeping, followed by a slight decrease towards malt. Extracts of seedlings and primary leaves had higher AP specific activities especially towards Phe- and Leu-2-NA. The differences between the cultivars were not significant. When electrophoretic protein patterns were compared it was possible to distinguish Angora barley from the other cultivars. The difference was more pronounced among water-soluble albumins/globulins then among prolamins, soluble in 55 % 2-propanol.

barley; germination; aminopeptidase; SDS-PAGE

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