| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 1999: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1998: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Research Abstract |
In order to find out the determining factor of starch characteristic in plant origin, we examined 1) molecular structure and function of high-amylose starches, 2) the relation between amount of granule bound starch synthase (GBSS) and amylose content and 3) the relation between function of branching enzyme (BE) and amylopectin structure. The results obtained suggested that GBSS and BE played an important role in characterization of starch.
1. We found that starches from two high-amylose cultivars of barley had similar molecular structures of amylose and amylopectin to a normal cultivar of barley, and were actually high-amylose, differing from in the case of indicia rice, and gelatinized with very difficulty.
2. We determined GBSS amount of starches from barley (4 cultivars), rice (12 cultivars), wheat (6 cultivars), maize (2 cultivars) and potato (5 cultivars) by SDS-PAGE, and found the following relations on GBSS amount. (1) Two types of plants were found in terms of the relation between GBSS amount and actual amylose content. One type of plant was barley and maize in which amylose content increased with increase of GBSS amount. The other type was rice, wheat and potato in which amylose content was constant even with increase of GBSS amount. (2) Rice GBSS, which synthesizes amylose, might also elongate a part of amylopectin chains and produce amylose-like very long chains.
3. BE was purified from barley endosperm (23 days later flowering). There were two isoforms (BE I and BE II), which had different function in chain transfer, and the main isoform, BE I, was suggested to determine short-chain distribution of amylopectin.
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