| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1986: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1985: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
THE MECHANISM OF DEVELOPMENT OF HEXANAL, ONE OF MAJOR ELEMENTS OF SOYBEAN FLAVOR, IN SOYBEAN WAS REVEALED AS FOLLOWS. SOYBEAN CONTAINS THREE TYPES OF LIPOXYGENASE ISOZYMES (L-1, L-2, L-3). OF THESE ISOZYMES, UNDER THE USUAL CONDITIONS (pH 6-7), L-2 ISOZYME PREDOMINATLY REACTS WITH LINOLEIC ACID TO FORM 13- AND 9-HYDROPEROXIDES OF LINOLEIC ACID. THE RESULTING 13-HYDROPEROXIDE (13-HPO) IS CLEAVED TO HEXANAL BY 13-HPO-LYASE. THE PRESENCE OF THE ENZYME IN SOYBEAN WAS FOUND ON THIS PROJECT. FROM KINETIC EXAMINATION OF THE TWO STEPS OF ENZYMATIC REACTIONS, IT IS CONCLUDED THAT A RATE-DETERMINIG STEP OF HEXANAL FORMATION FROM LINOLEIC ACID IS A STEP OF 13-HPO FORMATION BY LIPOXYGENASE L-2 ISOZYME, NOT A STEP OF 13-HPO CLEAVAGE BY 13-HPO-LYASE.
FOOD QUALITY OF LIPOXYGENASE DEFICIENT MUTANT SOYBEANS (L-1 NULL, L-2 NULL, L-3 NULL, L-1,-3 NULL) WAS ALSO INVESTIGATED. FOOS OOMPOSITION (MOISTURE, CRUDE PROTEIN, CRUDE FAT AND CARBOHYDRATE) OF THE SOYBEANS AND AMINO ACID COMPOSITION OF PROTEINS AND FATTY ACID COMPOSITION OF FAT FROM THEM WERE VERY SIMILAR TO THOSE OF NORMAL SOYBEAN (SUZUYUTAKA). RELATIVE EMULSIFYING ACTIVITY OF PROTEINS FROM THE SEEDS WAS ALSO SIMILAR TO THAT OF THE NORMAL SOYBEAN. THESE RESULTS SUGGEST THAT LIPOXYGENASE DEFICIENT SOYBEANS ARE USEFUL AS FOOD RESOURCES.
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