| Research Abstract |
1. A phenomenon that -amylase may be present in ungerminated corn seeds was observed. However, the phenomenon was presumed to be dependent on the cooperative actions by other different types of carbohydrate metabolizing enzymes, for example, -glucosidase, isoamylase, Q-enzyme, D-enzyme, etc. It was confirmed that thee was no -amylase in ungerminated corn seeds, and -amylase occurred first in the germination stage, like other cereal seeds.
2. Fouk kinds of -amylases appeared in the germinated seeds of yellow dent corn. Those enzymes increased rapidly after 4 days of imbibition (27゜C, in the dark).
3. An -amylase II was highly purified by various kinds of chromatographies. The molecular weight was about 48,000 and the optimum pH, 4.7. Maltose was mainly formed as final product from soluble starch.
4. Anomer of maltose produced was confirmed to be -form by GLC.
5. -amylase II was turned out to be typical endo-type enzyme from the curve of blue value for the hydrolysis degree of soluble starch.
6. The rates of hydrolyses for vaious -glucans decreased the following orde: amylose > soluble starch amylopectin > -limit dextrin >> glycogen.
7. Action patterns of -amylase II on a series of maltooligosaccharides (G_3 G_7, G_<18>) were examined by TLC and GLC. And the rate parameters (K_m and K_o) for the hydrolyese of maltooligosaccharides were determined.
8. On the basis of the action patterns and the rate parameters, the splitting point of each oligosaccharides and the subsite structure in active site were presumed, and the subsite affinities (A_i) were evalutaed. The number of subsites was assumed to be 7: A_1 = 0.3,A_2=0.3,A_3=0.7, A_4=2.7,A_5+A_6=-2.8,A_7=2.0 (Kcal/mol). The catalytic site was estimated to be present between the subsite 5 and 6.
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