Consolidation of Soybean Protein Coagulate

The process of dehydration of soybean protein coagulate in expression involves two mechanisms, filtration and consolidation. The filtration process was explained by Ruth’s filtration model. The consolidation process, except for secondary consolidation, was analyzed by the modified consolidation model of Shirato et al., taking into account the compressibility of cake. The modified coefficient of consolidation was not affected significantly by the pressure applied. Evaluation of the modified coefficient of consolidation is of importance for an attempt to improve the current production of soybean protein.     

Moisture Sorption Isotherms of Various Tobaccos

The equilibrium moisture contents of sun-cured (Kroumougrad), flue-cured (Bright Yellow—4) and air-cured (Burley-21 and Matsukawa) tobaccos were measured over a relative humidity range from 5 to 80% at 20°C. The moisture sorption isotherms of tobaccos were of sigmoid type, and classified into two groups. In a lower humidity range below ca. 40% RH, the A group (Kroumougrad and BY-4) had a smaller moisture sorption capacity than B group (Burley-21 and Matsukawa), while in a higher humidity range above ca. 50% RH the former had a larger moisture sorption capacity than the latter. By extracting with water, the moisture content of BY-4 was increased in the lower humidity range, while it decreased in the higher humidity range. However, the moisture content of Matsukawa was scarecely changed by extracting it with water. These results suggest that the differences in equilibrium moisture content with the type of curing were due to the differences in contents of water soluble com- ponents. To control the hygroscopic properties of a tobacco, therefore, the influences of the addition of sucrose and glycerol on the equilibrium moisture content were quantitatively analysed. The moisture sorption capacity of tobacco was greatly different from its nitrogen sorption capacity. The specific surface area of tobacco calculated from moisture sorption isotherm was ca. 110 times larger than the specific surface area calculated from the nitrogen sorption isotherm. Both the nitrogen and moisture sorption data should be necessary for better understanding of the complicated sorption-desorption phenomena in tobaccos.     

In vitro anticancer activity of loquat tea by inducing apoptosis in human leukemia cells

Fresh loquat leaves have been used as folk health herb in Asian countries for long time, although the evidence supporting their functions is still minimal. This study aimed to clarify the chemopreventive effect of loquat tea extract (LTE) by investigating the inhibition on proliferation, and underlying mechanisms in human promyelocytic leukemia cells (HL-60). LTE inhibited proliferation of HL-60 in a dose-dependent manner. Molecular data showed that the isolated fraction of LTE induced apoptosis of HL-60 as characterized by DNA fragmentation; activation of caspase-3, -8, and -9; and inactivation of poly(ADP)ribose polymerase. Moreover, LTE fraction increased the ratio of pro-apoptotic Bcl-2-associated X protein (Bax)/anti-apoptotic myeloid cell leukemia 1 (Mcl-1) that caused mitochondrial membrane potential loss and cytochrome c released to cytosol. Thus, our data indicate that LTE might induce apoptosis in HL-60 cells through a mitochondrial dysfunction pathway. These findings enhance our understanding for chemopreventive function of loquat tea.     

Isolation and Crystallization of Extracellular 3β-Hydroxysteroid Oxidase of Brevibacterium sterolicum nov. sp.

Among about 500 strains tested, a newly isolated soil bacterium, Brevibacterium sterolicum nov. sp. KY 3463 (ATCC 21387) showed the highest potency in production of 3β-hydroxysteroid oxidase in the culture fluid.

The 3β-hydroxysteroid oxidase was purified from the culture filtrate by a procedure involving ammonium sulfate fractionation, DEAE-cellulose and hydroxyapatite column chromatographies and Sephadex G–75 gel filtration. Crystals of the enzyme were obtained from solutions of the purified preparation by the addition of ammonium sulfate. The crystals appeared as fine rods, with a bright yellow color.

The enzyme is homogeneous by disc gel electrophoresis and ultracentrifugation. Sedimentation velocity yields a value of . It exhibits a typical flavoprotein spectrum of absorption maxima at 280, 390, and 470 mμ.     

Synergistic Taste Effects of Some New Ribonucleotide Derivatives

Taste effects of six newly synthesized ribonucleotide derivatives, i.e., disodium salts of 2-methyl-5′-inosinic acid · 6H₂O, 2-ethyl-5′-inosinic acid · 1.5H₂O, 2-N-methyl-5′-guanylic acid · 5.5H₂O, 2-N-dimethyl-5′-guanylic acid · 2.5H₂O, 2-methylthio-5′-inosinic acid · 6H₂O and 2-ethylthio-5′-inosinic acid · 2H₂O, were studied. Stimulus thresholds (detection thresholds) of these derivatives ranged from about 0.02 to 0.006 g/100ml. Flavor-enhancing activities of them were 2.3 to 8.0 times larger than that of disodium 5′-inosinate · 7.5H₂O IMP) in the synergistic effect with monosodium glutamate. Furthermore, the quality of taste of all the derivatives was recognized to be the same kind to that of IMP.     

Enzyme-Substrate Complex of p-Hydroxybenzoate Hydroxylase; One of the Activated Intermediates of the Overall Reaction

The transglucosidation reaction of brewer’s yeast α-glucosidase was examined under the co-existence of l-sorbose and phenyl-α-glucoside. As the transglucosidation products, three kinds of new disaccharide were chromatographically isolated. It was presumed that these disaccharides consisting of d-glucose and l-sorbose were 1-O-α-d-glucopyranosyl-l-sorbose ([α]_D+89.0), 3-O-α-d-glucopyranosyl-l-sorbose ([α]_D+69.1) and 4-O-α-d-glucopyranosyl-l-sorbose ([α]_D+81.0). The principal product formed in the enzyme reaction was 1-O-α-d-glucopyranosyl-l-sorbose.     

In vitro analysis of Bcl-2 proteins in mitochondria and endoplasmic reticulum: similarities in anti-apoptotic functions and differences in regulation

Anti-apoptotic Bcl-2 localizes in the membranes of mitochondria and endoplasmic reticulum (ER) and resists a broad range of apoptotic stimuli. However, the precise function of Bcl-2 in ER is still unclear. We herein examined the anti-apoptotic potencies of Bcl-2 in mitochondria and ER in vitro. The mitochondria isolated from HeLa cells, which have little or practically no Bcl-2, were apoptosis-competent. That is, membrane-bound Bax was activated and cytochrome c was released when the isolated mitochondria were incubated at 35 degrees C. Cytochrome c release from the apoptosis-competent mitochondria was suppressed by co-incubation with the mitochondria with overexpressed Bcl-2 (Bcl-2 mitochondria), suggesting that Bcl-2 anchored in one mitochondrion can suppress cytochrome c release from another mitochondrion. Similar results were obtained when microsomes with overexpressed Bcl-2 (Bcl-2 microsomes) were co-incubated with apoptosis-competent mitochondria. A quantitative titration analysis showed that Bcl-2 in the ER suppresses cytochrome c release as efficiently as that in the mitochondria. An immunoprecipitation assay showed that Bcl-2 in both mitochondria and ER binds to Bax at almost the same degree. However, in the presence of tBid, co-incubation of apoptosis-competent mitochondria with Bcl-2 microsomes, but not with Bcl-2 mitochondria, diminished the Bax-binding to Bcl-2 significantly, suggesting that Bcl-2 in ER is readily inactivated by tBid. Co-incubation assay further confirmed that Bcl-2 in the ER, but not Bcl-2 in the mitochondria, is potentially inactivated by tBid. Our quantitative in vitro studies indicate that Bcl-2 in mitochondria and ER are similarly potent in inhibiting Bax-associated apoptosis of other mitochondria, but are regulated by tBid differently.     

The antioxidative function of eicosapentaenoic acid in a marine bacterium, Shewanella marinintestina IK-1

When the eicosapentaenoic acid (EPA)-deficient mutant strain IK-1Delta8 of the marine EPA-producing Shewanella marinintestina IK-1 was treated with various concentrations of hydrogen peroxide (H(2)O(2)), its colony-forming ability decreased more than that of the wild type. Protein carbonylation, induced by treating cells with 0.01 mM H(2)O(2) under bacteriostatic conditions, was enhanced only in cells lacking EPA. The amount of cells recovered from the cultures was decreased more significantly by the presence of H(2)O(2) for cells lacking EPA than for those producing EPA. Treatment of the cells with 0.1 mM H(2)O(2) resulted in much lower intracellular concentrations of H(2)O(2) being consistently detected in cells with EPA than in those without EPA. These results suggest that cellular EPA can directly protect cells against oxidative damage by shielding the entry of exogenously added H(2)O(2) in S. marinintestina IK-1.