A thermostable Gm-methylase recognizes the tertiary structure of tRNA

The efficiency of methylation of tRNA by a thermostable tRNA(guanosine-2')-methyltransferase (Gm-methylase) was examined at various temperatures using several species of tRNA isolated from Escherichia coli, yeast and Bacillus subtilis, each possessing different thermal properties. The optimal temperature for the methylation reaction was ca. 20 degrees C lower than the melting temperature of the tRNA in each case. Arrhenius plots of the methylation reactions with various tRNAs gave straight lines below the optimal temperatures in all cases, with similar activation energies of between 10 and 14 kcal/mol. Above the optimal temperatures, the methyl acceptor activity decreased as the incubation temperature was raised to 80 degrees C, at which point the methylase was still active. A correlation was observed between the remaining methyl acceptor activity and the hyperchromicity of tRNA. These results suggest that Gm-methylase recognizes the tertiary structure of tRNA, and it is not the substrate tRNA but the enzyme which is activated by heat.     

Enzymatic synthesis of anticodon-deleted and replaced Bacillus subtilis tRNAThr and their amino acid acceptor activity

By some enzymatic and chemical procedures, one or two nucleotides in the anticodon region of Bacillus subtilis tRNAThr were deleted and a part of the anticodon sequence was replaced. The anticodon-deleted molecules retained amino acid acceptor activity although the activity was low. However, the anticodon-replaced molecule which has a lysine specific sequence (U-U-U) exhibited neither threonine acceptor activity nor lysine acceptor activity.     

Purification and Some Properties of Carboxyl Proteinase in Mycelium of Lentinus edodes

The effect of Streptomyces-pepsin inhibitor (S-PI) on fruit-body formation of Lentinus edodes (Berk.) Sing, was studied. The addition of S-PI to the culture medium (5 ~ 10 µg/ml) shortened the time required for mature fruit-bodies, and increased the fruiting-percentage and the overall yield 3.4 times compared to the control.

The intracellular proteinase in the mycelium was investigated. Proteinases having an optimal pH of 2.7 and 7.0 were found in the vegetative mycelial extract. When S-PI was added to the culture medium, their activities were strikingly changed; the carboxyl proteinase activity was remarkably decreased, and, in the contrary, the metal proteinase activity was increased to 1.5 times that of the control.

The carboxyl proteinase was purified. This enzyme was strongly inhibited by S-PI and synthetic pepsin inhibitors such as DAN and EPNP. The molecular weight and isoelectric point were 43,000 and pH 3.4, respectively.     

Okaramine A,a Novel Indole Alkaloid with Insecticidal Activity,from Penicillium simplicissimum AK-40

We evaluated the neurotrophic activity of dietary polyphenols by using primary cultures of fetal rat hippocampal neurons in a serum-free medium. Among the tested compounds, chlorogenic acid and its metabolite, m-coumaric acid, together with catechins and flavanone, were found to promote neuronal differentiation comparable to the phytochemical, honokiol, which has been reported to show potent neurotrophic activity. The present findings may contribute to the development of further neurotrophic studies on dietary polyphenols and their metabolites.     

Partial Structure of Glycopeptide Obtained from Scytalidium lignicolum Acid Protease A

The partial structure of glycopeptide moiety of new acid protease A isolated from Scytalidium lignicolum ATCC 24568 was studied by Smith degradation, methylation and partial acetolysis techniques. The main product, glycopeptide V (GP-V), obtained by Pronase digestion was composed of mannose, glucosamine, asparagine, serine and glycine in an approximate molar ratio of 10: 3: 2: 1: 1, and a possible structure was proposed as follows:     

Isolation and Identification of a Microorganism which Produces Non Streptomyces Pepsin Inhibitor and N-Diazoacetyl-dl-norleucine Methylester Sensitive Acid Proteases

Non pepsin inhibitor (S–PI) and diazoacetyl-dl-norleucine methylester (DAN) sensitive acid proteases producing microorganism was isolated from farm soil of Osaka Prefecture.

The isolated strain was identified as Scytalidium lignicolum M–133. When it was aerobically grown on a medium consisting of glucose 5%, meat extract 1.5%, yeast extract 0.1%, KH₂PO₄ 0.2%, MgSO₄·7H₂O 0.05% at pH 3.5 and 25°C, the strain produced two acid proteases, A and B, in the culture broth.

The acid proteases A and B were not at all inactivated by S–PI and DAN. These acid proteases were expected to be a new type of acid protease from the viewpoint of the active site.     

Exaggerated envy and guilt measured by economic games in Japanese women with anorexia nervosa

Background

Anorexia nervosa (AN) patients are assumed to express high levels of guilt and envy. Ultimatum game (UG) is a standard behavioral task that focuses on interpersonal behavior when splitting a sum of money between two players. UG studies consistently demonstrate that people tend to decrease their inequity in outcomes, one explanation being that economically irrational decision-making may partly arise from the emotions guilt and envy. We assumed that AN patients would perform excessively fair in UG, reflecting high guilt and envy.

Methods

We utilized UG to investigate the characteristics of guilt and envy among 24 Japanese AN patients and 22 age-matched healthy controls (HC). The relation between the outcome of UG and decision strategy confirmed by post-experimental questionnaires was analyzed.

Results

As proposer, AN offered a larger amount to the responder compared with HC (p?=?0.002) while, on the other hand, as responder, AN demanded much higher allocation to accept the offer compared with HC (p?=?0.026). Regarding the strategy as responder, AN put more emphasis on fairness and less emphasis on monetary reward compared with HC (p?=?0.046, p?=?0.042, respectively).

Conclusions

The results indicate that Japanese AN patients demonstrate strong preference for fairness, with high guilt and high envy. High sensitivity to guilt and envy of AN patients can affect not only their own behavior concerning eating attitude and body shape, but also decision-making in interpersonal situations. Behavioral experimental settings among social situations will enable us to evaluate and help actual decision-making in the real life of patients.

     

Purification and Some Properties of an α-Amylase Inhibitor (Paim) from Streptomyces corchorushii

Paim, a microbial animal amylase inhibitor, was purified from the culture filtrate of Streptomyces corchorushii by salting out with ammonium sulfate and column chromatography on DEAE-cellulose, TEAE-cellulose, SP-Sephadex C-50, and Octyl Sepharose CL-4B. Paim was separated into 2 fractions (Paim I and II), both homogeneous on disc electrophoresis. The molecular weight of Paim I was 4100 and that of II, 4400 by amino acid analysis. Paim I and II consisted of 39 and 42 amino acid residues, respectively, and contained no lysine, isolecucine, or phenylalanine. Paim contained no carbohydrate moiety, and was stable even after being treated at 100°C for lOmin in the pH range from 5 to 8.