The frying properties of the batter used in making Tempura, i.e., Koromo, prepared from wheat protein and starches from waxy maize, maize, wheat, tapioca, and potato, have been examined. The water evaporation rate, oil absorption, breaking strength and sensory evaluation scores of Koromo varied with the starch origin. Among these properties, the water evaporation rate correlated with the breaking strength (r = 0.96), crispness score (r = 0.92) and hardness score (r = 0.97) when the Koromo having a ratio of water to protein-starch of 160% (w/w) was fried at 170t for 60 s. During frying, the temperature of Koromo rapidly increased to about 105°C, at which temperature it remained for a while, and then increased gradually. Koromo, holding a temperature of about 105°C for a long time, showed a higher water evaporation rate. Koromo with a higher water evaporation rate showed a higher breaking strength and crispness score, and was evaluated to have a more favorable quality. Maize starch gave a good quality of Koromo, whereas waxy maize and tapioca starches gave an inferior quality, and wheat and potato starches showed an intermediate quality. Scanning electron microphotographs revealed the presence of starch granules in Koromo of a good quality after frying but absence in Koromo of an inferior quality.

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The substrate binding ability of Taka-amylase A (TAA) was evaluated by chemical modification, affinity gel electrophoresis and affinity chromatography methods.. Compared with modifications of the amino group with o-phthalaldehyde (OPA) and 2, 4, 6-trinitrobenzenesulfonic acid (TNBS), modification of the Trp residue with N-bromosucciniimide (NBS) caused a strong and rapid inactivation of TAA. NBS-modified TAA greatly impaired the affinity to substrate soluble starch. Based on these results and previous results of isolation of substrate-binding peptides, all of which contained Trp residues in the sequence [Y. SASAKI et al.: Biosci. Biotech. Biochem., 61, 1840-1843 (1997)], it was strongly suggested that Trp residues in the TAA molecule played an important role in substrate binding and subsequently in the catalytic activity. Moreover, affinity analyses, which were useful for the evaluation of enzyme affinity to substrates or its analogs having low susceptibility to TAA in the activity measurement, indicated that TAA could recognize the dextran molecule as the substrate analog.

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The solubility and some inclusion characteristics of the newly developed sugar, cyclodextran (cyclic isomaltooligosaccharides: heptamer, CI-7; octamer, CI-8; nonamer, CI-9), were compared with those of cyclodextran (CD: hexamer, α-CD; heptamer, β-CD; octamer, γ-CD). In spite of the high solubility of CI in water, CI-9 was readily precipitated by mixing with 80% ethanol and n-propanol. Rather higher interactions of CIs with Trp than CDs were observed. Although CDs gave higher amounts of precipi-tate upon reaction with various surfactants, the interaction of CIs with surfactants was rather poor. The precipitate formation of CIs was greatly improved by the addition of 73% ethanol or acetonitrile, suggesting that a decrease in the solubility of CIs would lead to an increase in inclusion reactions. The action of α-glucosidase on the substrate phenyl a-glucoside was inhibited by CIs, while CDs gave opposite results accelerating the enzyme reaction.

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A cDNA coding a-amylase of Phaseolus vulgaris L. cv. Toramame was isolated and sequenced. PCR primers were synthesized based on the partial amino acid sequences of the purified a-amylase. The DNA fragment amplified by PCR with the primers was applied as a probe to screen the cDNA library representing mRNA in the cotyledons of germinating seeds. The cDNA sequence in the positive clone encoded a unique 1263-nucleotide open reading frame flanked by 5'- and 3'-untranslated regions of 6 and 194 nucleotides, respectively. The open reading frame encoded a protein of 420 amino acid residues including a 23 amino-acid-long signal peptide. The kidney bean a-amylase shows over 70% similarity in the amino acid sequence with other dicotyledonous plant a-amylases. Especially, 94% of the residues are identical to a-amylase from Vigna radiate. Kidney bean a-amylase also has all four sequence regions highly conserved in enzymes belonging to the amylase family.

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α-Secondary deuterium kinetic isotope effects were investigated in the hydrolysis of [1, 1'.2H]-isomaltose with Aspergillus niger α-glucosidase, suger beet a-glucosidase, honeybee a-glucosidase II, and Paecilomyces sp. glucoamylase. The ratios kH/kD of the molecular activities in the hydrolysis of an ordinary isomaltose and the [1, 1'-2H] isomaltose enzymatically synthesized were 1.16, 1.21, 1.13, and 1.23 for α-glucosidases from A. niger, sugar beet seeds, and honeybees, and glucoamylase from Paecilomyces sp., respectively. The data strongly support the occurrence of the oxocarbenium ion intermediate in the transition states of the hydrolytic reactions by the glycosidases.

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Sugar beet homogenate contained high activities of pectinase together with invertase and several other enzymes. Upon an autolysis of sugar beet homogenate, rapid hydrolysis of sucrose at pH 7.6 and 20-30°C was observed. Prolonged autolysis resulted in a significant decrease in the amount of reducing sugar. Crude enzyme prepared from the supernatant of sugar beet homogenate converted neutral and acidic sugars into non-reducing compounds. Therefore, the use of sugar beet enzymes for the saccharification of beet pulp and subsequent ethanol production was not practically applicable in spite of the good hydrolysis activity to the beet pulp polysaccharides. From the viewpoint

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The localization of a-glucosidase and β-fructofuranosidase (invertase) in the cells of Schizosac-charomyces pombe, Saccharomyces logos, and Saccharomyces cerevisiae was investigated. Most of the enzymes were found to be localized in periplasmic fraction in the cells grown on both culture media, one containing only glucose and the other a mixture of glucose and maltose. These findings suggest that α-glucosidase and invertase synthesized inside protoplast are quickly secreted to be placed outside the cell membrane, periplasm. Only in the case of S. cerevisiae grown on glucose culture medium, the α-glucosidase was detected in protoplast.

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