Cereal Chem 51:508 - 528. | VIEW
Wheat Alpha-Amylases. II. Physical Characterization.
R. Tkachuk and J. E. Kruger. Copyright 1974 by the American Association of Cereal Chemists, Inc.
Four alpha-amylase isoenzymes were isolated from malted hard red spring wheat. Isoenzyme purity was established by rechromatography on DEAE-cellulose, gel and sodium dodecyl sulfate (SDS) electrophoresis, and sedimentation velocity studies. The alpha-amylases were similar except for electrophoretic mobility and chromatography elution times. The purified isoenzymes have average sedimentation and diffusion coefficients of approximately 3.71s and 7.19 x 10(-7) cm.2 sec.-1. Molecular weights from sedimentation velocity/diffusion and SDS gel-electrophoresis data were 45,100 and 42,000. The alpha-amylases are acidic proteins with relatively large amounts of glutamyl, aspartyl, and glycyl residues and have isoelectric points between pH 6.05 and 6.20. Maximum enzymatic activity occurs at pH 5.5 to 5.6. Wheat alpha-amylase does not contain sulfhydryl groups but does have two disulfide bonds per residue.