Effects of dietary fat energy restriction and fish oil feeding on hepatic metabolic abnormalities and insulin resistance in KK mice with high-fat diet-induced obesity

We investigated the effects of dietary fat energy restriction and fish oil intake on glucose and lipid metabolism in female KK mice with high-fat (HF) diet-induced obesity. Mice were fed a lard/safflower oil (LSO50) diet consisting of 50 energy% (en%) lard/safflower oil as the fat source for 12 weeks. Then, the mice were fed various fat energy restriction (25 en% fat) diets — LSO, FO2.5, FO12.5 or FO25 — containing 0, 2.5, 12.5, or 25 en% fish oil, respectively, for 9 weeks. Conversion from a HF diet to each fat energy restriction diet significantly decreased final body weights and visceral and subcutaneous fat mass in all fat energy restriction groups, regardless of fish oil contents. Hepatic triglyceride and cholesterol levels markedly decreased in the FO12.5 and FO25 groups, but not in the LSO group. Although plasma insulin levels did not differ among groups, the blood glucose areas under the curve in the oral glucose tolerance test were significantly lower in the FO12.5 and FO25 groups. Real-time polymerase chain reaction analysis showed fatty acid synthase mRNA levels significantly decreased in the FO25 group, and stearoyl-CoA desaturase 1 mRNA levels markedly decreased in the FO12.5 and FO25 groups. These results demonstrate that body weight gains were suppressed by dietary fat energy restriction even in KK mice with HF diet-induced obesity. We also suggested that the combination of fat energy restriction and fish oil feeding decreased fat droplets and ameliorated hepatic hypertrophy and insulin resistance with suppression of de novo lipogenesis in these mice.     

Red Yeast Cell Lysis by Red Yeast Cell Wall Lytic Enzyme and Protease

The purified red yeast cell wall lytic enzyme of Penicillium lilacinum No. 2093 has a potent saccharifying activity against cell walls, but the living cell lytic activity of it is considerably lower than that of the culture filtrate. Therefore, the living cell lytic factors in the culture filtrate were examined. The alkaline protease of Pen. lilacinum played an important role for living cell lysis. The synergistic effect on living cell lysis was also detected, when acid proteases from various origins were combined with the cell wall lytic enzyme. These results indicated that the protein layers of red yeast cell surface inhibited the action of a glycanase,cell wall lytic enzyme, and the protein molecule contributed to retain the rigid structure of the wall.     

Antifreeze Emulsions Produced from Linoleic Acid and Water Using Enzymatically Modified Gelatin

An enzymatically modified gelatin with covalently attached leucine dodecyl ester, referred to as EMG-12, was used as a surfactant to prepare emulsions with different properties by changing the surfactant concentration, oil volume fraction, and pH in the water phase. The emulsions generally resisted the freezing of their constituent bulk water at approximately ?10°C, but similar emulsions produced with soy protein isolate, casein, or Tween-80 as control agents were less resistant. The freezing (or unfreezing) of the bulk water in these emulsions depended on the kind of agent used, not on the emulsion properties such as average area of the oil/water interface, stability against coalescence, and stability against creaming. The emulsion produced with EMG-12, like that produced with polyglycerol stearate, tended to maintain its unfrozen state even in the presence of silver iodide crystals added as heterogeneous ice-nuclei. The significance of producing such an antifreeze emulsion is discussed from the standpoint of cryopreservation of cold-sensitive food and biological systems.     

Salt Effects on Plastein Formation by α-Chymotrypsin

The plastein formation by α-chymotrypsin from an ovalbumin hydrolysate was affected in an order of valency of salts when the concentration of each salt was 1 m. Monovalent cations were rather effective at this concentration and enhanced the plastein yield by 10%. In the presence of NaCl, the plastein formation showed two distinct maximal rates at its concentrations of 0.1 m and 0.8 m. The first maximum was considered to be resulted from an increase in enzyme activity, since chymotryptic hydrolysis of both N-acetyl-l-tyrosine ethyl ester and benzyloxycarbonyl-l-phenylalanine p-nitrophenyl ester was activated at an NaCl concentration of 0.1 ~ 0.2 m. The second maximum was ascribed to the salting-out of the product due to the higher concentration of NaCl. A salt-tolerant protease was also used to confirm the above conclusions. It was observed that this enzyme was much effective in producing a plastein at a high NaCl concentration. This may be due to the fact that both the enzyme activation effect and the product salting-out effect participate co-operatively.     

Isolation and Identification of a Hog Pancreatic α-Amylase Inhibitor (Haim) Producing Streptomyces

A screening test was carried out to obtain microbes which produce hog pancreatic α-amylase inhibitor and a new inhibitor was found in culture broth of an actinomycete, strain YM-25. This inhibitor was designated as Haim, an abbreviation for hog pancreatic α-amylase inhibitor from a microbe. The determined morphological and physiological properties of strain YM-25 led to the conclusion that the microorganism was Streptomyces griseosporeus.

When the microorganism was aerobically cultured at 30°C in a jar fermentor containing the most suitable medium for growth which consisted of 5% glycerol, 0.5% polypepton, 0.2% meat extract, 0.1% yeast extract, 0.4% Na₂HPO₄ ? 12H₂O, 0.1% KH₂PO₄, and 0.05% MgSO₄ ? 7H₂O (pH 7.3), the highest activity of Haim was obtained on 23~26hr cultivation.

Haim had specific inhibitory activities against animal α-amylases but not against microbial and plant α-amylases.     

Substitution Reaction on the Indole Ring of ( – )-Indolactam V,the Fundamental Structure of Teleocidins

We isolated a temperature-sensitive mutant which did not exhibit derepression of acid phosphatase and invertase at the restrictive temperature. The mutation was mapped in the cryl gene, the structural gene for the catalytic subunit of adenylate cyclase. On electron microscopic observation of the mutant cells at the restrictive temperature, it was observed that they accumulated carbohydrate particles in the cytoplasm. Isolated particles had a rosette-like structure of 40 to 60 nm in diameter, and were identified as glycogen. After 2 hr incubation at the restrictive temperature, glycogen particles occupied most of the cytoplasmic space and the vacuoles were observed to be fragmented.     

Purification and Characterization of a Surface-active Macropeptide Produced from Succinylated αs1-Casein by Modification with Papain

The preceding paper described that when succinylated α_s1-casein, ca. 25,000 daltons, was modified with papain in the presence of l-leucine n-dodecyl ester (Leu-OC₁₂), an approximately 20,000-dalton macropeptide was formed as the main product. In the present work we have investigated its chemical structure and surface function. A treatment for purification at the petroleum ether/water interface gave an electrophoretically homogeneous 20,000-dalton macropeptide which functioned as a surfactant to emulsify corn oil as well as n-octane. Pulsed NMR and ESR studies demonstrated that the macropeptide, when used to emulsify n-octane in water, acted to restrict the mobility of those molecules involved in the emulsion. Various data from chemical analyses coupled with knowledge about the primary structure of α_s1-casein showed that the 20,000-dalton macropeptide was structured as succinyl-Arg¹-….-Phe¹⁴⁵-Leu-OC₁₂. A discussion is included to explain the surface function of this peptide in relation to its amphiphilic structure.     

General Properties of a Plastein Synthesized from a Soybean Protein Hydrolysate

By use of pepsin a plastein was synthesized from a peptic hydrolysate of soybean protein and characterized as a protein-like substance, based on its behavior against trichloroacetic acid and its affinity to dyes. The contribution of the S–S bridge to plastein formation was little if any. The fractionation of the protein-like substance by solubility showed that the whole plastein-reaction product was constituted of 81.5 parts of the 50% ethanol-insoluble fraction; 63.8% of this fraction was also insoluble in 0.035 M phosphate buffer (pH 7.6). The phosphate buffer-insoluble fraction was mostly solubilized in 0.3 M sodium dodecyl sulfate (SDS). Although it was a minor component, there was a 50% ethanol-soluble and water-insoluble (prolamine-like) fraction which showed a reversible aggregation-dispersion change by a repeated heating-cooling treatment. A characteristic point of the SDS-soluble and prolamine-like fractions was found in their amino acid compositions. As compared with the substrate (peptic hydrolysate of soybean protein), they contained larger amounts of hydrophobic amino acids such as leucine than hydrophilic ones typified by glutamic acid.     

A monosaccharide-modified peptide phage library for screening of ligands to carbohydrate-binding proteins

A monosaccharide-modified β-loop peptide library displayed on phage has been constructed and used for the screening of glycopeptide ligands against a carbohydrate-binding protein. The β-loop peptide library was designed and modified with a mannose derivative on phage. The glycopeptide ligands to concanavalin A (ConA), a mannose-binding protein, were obtained from the mannose-modified peptide phage library. The amino acids neighboring the mannose unit of glycopeptides not only reinforced the binding affinity but also gave diverse binding characteristics.