Takaharu Tanaka

Synthesis of a new cell penetrating calpain inhibitor (calpeptin)

N-terminal of Leu-norleucinal or Leu-methioninal was modified to obtain a cell penetrative peptide inhibitor against calpain. Benzyloxycarbonyl (Z) derivatives had less active against papain than phenylbutyryl derivatives and leupeptin. Z-Leu-nLeu-H (calpeptin) was more sensitive to calpain I than Z-Leu-Met-H and leupeptin. Calpeptin was most potent among synthesized inhibitors in terms of preventing the Ca2+-ionophore induced degradation of actin binding protein and P235 in intact platelets. After 30 min incubation with intact platelets, calpeptin completely abolished calpain activity in platelets but no effect was observed in case of leupeptin. Calpeptin also inhibited 20K phosphorylation in platelets stimulated by thrombin, ionomycin or collagen. Thus calpeptin was found to be a useful cell-penetrative calpain inhibitor.

Hydrodynamic characteristics of a butterfly valve — Prediction of pressure loss characteristics

Abstract Investigation on fluidmechanic performance on a butterfly valve has been carried out. A practical valve model of a given thickness and a hub is used for the loss coefficient theory. A theoretical loss coefficient has been formulated from a contraction factor obtained by applying the generalized Borda mouthpiece theory. Cavitation stages (such as cavitation inception, supercavitation inception, cavitation damage inception, choking cavitation) have been theoretically predicted from the valve loss coefficient. The cavitation prediction has been carried out by applying the free streamline theory, where the relation between the loss coefficient and the critical cavitation factor has been formulated. The results of the theoretical prediction equations agree well with the experimental results.

Synthesis of the mating factor of Saccharomyces cerevisiae and its truncated peptides : the structure-activity relationship.

Abstract The mating factor of Saccharomyces cerevisiae, Trp-His-Trp-Leu-Gln-Leu-Lys-Pro-Gly-Gln-Pro-Met-Tyr, has been synthesized to confirm the structure of the natural mating factor. The tridecapeptide has the same biological activity as the natural mating factor. From the studies on the biological activity of its truncated peptide synthesized the minimum sequence of the peptide require for the mating factor was deduced to be as His-Trp-Leu-Gln-Leu-Lys-Pro-Gly-Gln.

Synthesis and Inhibitory Activity of Acyl-Peptidyl-Pyrrolidine Derivatives Toward Post-Proline Cleaving Enzyme; A Study of Subsite Specificity

Several pyrrolidine derivatives have been synthesized and examined for their inhibitory activity on post-proline cleaving enzymes from Flavobacterium meningosepticum and bovine brain. Almost all the compounds tested in this study inhibited the activity of both enzymes at low IC50 values (from nM to microM) but a specificity difference was observed with alkylacyl-peptidyl-pyrrolidine derivatives which strongly inhibited only the bacterial enzyme. The most effective inhibitors have a proline residue on their P2 sites and a substituted or unsubstituted phenoxybutyryl moiety on their P3 sites. Thus phenoxybutyryl-prolyl-pyrrolidine is the most effective partial structure of the inhibitors. The best inhibitors found were: 4-(4-benzylphenoxy)butyryl-prolyl-pyrrolidine for bacterial enzyme (IC50 1.4 nM) and 4-phenylbutyryl-thioprolyl-pyrrolidine for bovine brain enzyme (IC50 67 nM). In the passive avoidance test, using amnesic rats experimentally induced with scopolamine, the pyrrolidine derivatives which had potent inhibitory activity toward post-proline cleaving enzymes also showed strong anti-amnesic activities at doses of 1-5 mg/kg, i.p.

Low molecular RNA associated with chromatin Purification and characterization of RNA that stimulates RNA synthesis

Abstract 1. Two species of RNA, 5.0 S and 4.5 S, have been purified from chick liver chromatin that stimulate specifically RNA synthesis in vitro with chromatin as template. 2. When DNA is employed as template, both RNAs are inhibitory for RNA synthesis. With chick liver chromatin as template, such stimulation is not observed with any other RNA or polyanion such as synthetic polyribonucleotide or polyvinyl sulfate. 3. Base analysis indicates that these species of RNA have a relatively higher content of uridylic acid, and available evidence suggests that 5.0-S and 4.5-S RNA are functionally unique in regulating genetic activity.

Studies on low molecular weight RNA of chromatin: Effects on template activity of chick liver chromatin

Abstract 1. 1. An RNA fraction was partially purified from chick liver chromatin. This RNA showed a sedimentation constant of 7–10 S upon sucrose density gradient analysis. 2. 2. This species of RNA inhibited the RNA synthesis in a cell-free system of Escherichia coli RNA polymerase with DNA as template, whereas with chick liver chromatin as template, the RNA synthesis was shown to be stimulated by the addition of this particular RNA. 3. 3. Preliminary analyses revealed that the RNA showed higher affinity to chromatin isolated from the same tissue, and presumably modified its structure to serve as template for RNA synthesis.

Amino acid substitution of mating factor of Saccharomyces cerevisiae: Structure-activity relationship

Analogs of the mating factor of Saccharomyces cerevisiae, Trp1- Trp3-Leu-Gln-Leu6-Lys7-Pro8-Gly-Gln-Pro11-Met12-Tyr13, from which amino acids were eliminated or substituted for other amino acid, were synthesized. These analogs showed lower biological activity than the natural mating factor if assayed after 6 hours incubation with a-mating type cells of S. cerevisiae. However, if assayed after 24 or 48 hours incubation, the situation changed, i.e. the analogs in which Leu6 or Lys7 were replaced by the corresponding D-isomer, showed higher mating factor activity than the unsubstituted mating factor. The same result was obtained with the analogs in which Met was replaced by norleucine.

Synthesis and Inhibitory Activity of Acylpeptidyl-Prolinal Derivatives Toward Post-Proline Cleaving Enzyme as Nootropic Agents

Several prolinal derivatives were synthesized and examined for their inhibitory activity on post-proline cleaving enzymes from Flavobacterium meningosepticum and bovine brain and their possible properties as nootropic agents. Almost all the compounds tested inhibited the activity of both enzymes at low IC50 values of the order of nM, but a specificity difference was observed with alkylacyl-prolinal derivatives which strongly inhibited only the bacterial enzyme. Prolyl-prolinal derivatives were the most effective inhibitors for both enzymes. In the passive avoidance test using amnesic rats experimentally induced with scopolamine, the prolinal derivatives that have potent inhibitory activity toward post-proline cleaving enzymes showed also strong anti-amnesic activities at dose of 10-1000 micrograms/kg, i.p. Some of the compounds showed a bell-shape dose dependency. These results suggest that the post-proline cleaving enzymes play an important role in the regulation of learning and memory consolidation in the brain and inhibitors of these enzymes are suggested as possible candidates for nootropic agents, particularly for an anti-amnesic drug.

Chicken extract stimulates haemoglobin restoration in iron deficient rats

Chicken essence is widely used as a traditional remedy for several ailments including anaemia. To test this claim for objective evidence, a series of experiments was carried out in anaemic rats by supplementing iron deficient diets with either liquid or lyophilised essence, which contains mainly protein and peptides (83 mg/ml) and free amino acids (3.1 mg/ml), very little iron (1 microgram/ml), and no fat. Haemoglobin returned to normal significantly more rapidly in rats supplemented with ad libitum liquid BEC over a period of up to 27 days compared with controls fed only water in addition to the ad libitum iron deficient diet. Haemoglobin was also significantly increased after 1 week in animals fed ad libitum diets supplemented with lyophilised chicken essence than with controls fed the unsupplemented diet. The effect was greater with supplementation at the level of 0.2% than at 1% lyophilised essence. The results indicate that the effects were mediated by increased appetite and by enhanced availability of food iron. These studies provide objective evidence for the traditional belief that chicken essence remedies anaemia.

Site of action of mating factor in a-mating type cell of Saccharomycescerevisiae

Abstract The process of the entry of FITC-conjugated mating factor into a -mating type cells of Saccharomyces cerevisiae and its concentration into the nucleus were observed. But, when α -mating type cells or diploid cells of S. cerevisiae were incubated with the FITC-conjugated mating factor, its adsorption to the cell surface of the test organisms and its incorporation into the cell did not occur. The peptides formed by the cleavage of mating factor by α -mating type cells of S. cerevisiae were not adsorbed onto a -mating type cells.