Potential use of plant extracts for reducing salt intake was explored. Recent finding of GAD67 and GABA-gated chloride ion channel GABAA receptors being expressed in type III taste buds supported an idea that GABA could be a signal for salty taste mechanism. In this study, we have shown that food extracts effected on both GAD67 activity in vitro and taste sensations in vivo. Furthermore, those food extracts tended to enhance GAD67 activity showed direct correlation with salty taste enhancement. It is concluded that food extracts can be a useful salt enhancing materials.

抄録全体を表示

A starch removal method from a wheat bran medium was established using citric acid. Secreted enzymes from cultivated A. oryzae RIB40 were then investigated. The specific activity of α-amylase decreased while that of xylanase and xylosidase increased 2-fold and 7-fold, respectively. Proteomics analysis identified three new α-glucosidases and two new α-glucanases. DNA microarray identified high expression of three new endo glucanases and one α-xylosidase. The expression of β-1,4 xylanase was increased 27-fold.

抄録全体を表示

Carboxypeptidase Y (CPY) is a vacuolar serine-type protease of yeast Saccharomyces cerevisiae to release wide variety of L-amino acid including proline from C termini of peptides and proteins. According to three-dimensional structure of mature CPY determined crystallographically, there is a characteristic region constructed with two adjacent α-helices, called ‘V-shape helix’, which lies over the active site cavity just like a door. In order to clarify the role of V-shape helix, we attempted to immobilize the V-shape helix by introducing amino acid substitution to create additional disulfide bridge between the V-shape helix and the main body of CPY. Resulting mutant enzymes presented with misfolding or hydrolase activity loss, suggesting that replacement of the residues at or near V-shape helix would influence on the protein folding and enzyme activity. The results of this report demonstrated that the insertion domain including V-shape helix in α/β hydrolasefold serine carboxypeptidases plays a role in the construction of functional enzyme.

抄録全体を表示

Food extracts from spices and teas were examined for the taste altering ability on sweet, umami and bitter tastes by using the taste sensation test. The idea arose based upon the findings that 1) some food extracts from spices and teas act as salt taste enhancers and 2) the enhancing effect is directly proportional to glutamate decarboxylase 67 (GAD67) activity in vitro. Our results indicated that those extracts significantly activated or inhibited GAD67 enzyme activity were able to alter sweet, umami, and bitter tastes. However, there were no relationships between the taste potency of each of the examined extracts and the GAD67 relative activity ratio. While it is unlikely that the extracts have directly activated GAD67 activity and enhanced sweet, umami or bitter tastes, the results do not exclude the idea that GABA may participate in the taste cell-to-cell communications.

抄録全体を表示

We screened for inhibitory activities of 25 wild vegetables and fruits for human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT). Among them, ethanol- and water-extracts of Brasenia schreberi (Junsai) and water-extract of Petasites japonicus (Fuki) strongly inhibited the HIV-1 RT activity to incorporate dTTP into poly(rA)-p(dT)15. We tested HIV-1 RT inhibitory activities of 15 polyphenols, isolated from Brasenia schreberi. Among them, gossypetin and hypolaetin 7-O-glucoside inhibited the activity.

抄録全体を表示