Rice bifunctional alpha-amylase/subtilisin inhibitor: characterization, localization, and changes in developing and germinating seeds.
A bifunctional alpha-amylase/subtilisin inhibitor (RASI) was purified to electrophoretic homogeneity from rice (Oryza sativa L.) bran. Its molecular mass was 21 kDa by SDS-PAGE and its isoelectric point was 9.05. Purified RASI inhibited subtilisin Carlsberg strongly and inhibited alpha-amylase from germinating rice seeds weakly. It inhibited rice alpha-amylase more than barley alpha-amylase, and the inhibition of rice alpha-amylase was greater at higher pHs. RASI did not inhibit trypsin, chymotrypsin, cucumisin, or mammalian alpha-amylase. The RASI was in the outermost part of the rice grain and its subcellular site seemed to be aleurone particles in aleurone cells. SDS-PAGE and western blotting showed that RASI was synthesized in the late milky stage in developing seeds, and it remained fairly constant during the first 7 days of germination.
Yamagata
H
H
Laboratory of Biochemistry, Faculty of Agriculture, Kobe University, Japan.
Kunimatsu
K
K
Kamasaka
H
H
Kuramoto
T
T
Iwasaki
T
T
D015153:Blotting, Western; D003432:Cross-Linking Reagents / Q000737:chemistry*; D018525:Germination; D006801:Humans; D006863:Hydrogen-Ion Concentration; D012275:Oryza / Q000737:chemistry*; D010940:Plant Proteins / Q000302:isolation & purification / Q000502:physiology*; D012639:Seeds / Q000737:chemistry*; D013381:Subtilisins / Q000037:antagonists & inhibitors*; D000516:alpha-Amylases / Q000037:antagonists & inhibitors*
D003432:Cross-Linking Reagents; D010940:Plant Proteins; D000516:alpha-Amylases; D013381:Subtilisins