Antibacterial action on pathogenic bacterial spore by green tea catechins

Antibacterial effects of catechins, the major green tea polyphenols, were studied using Clostridium and Bacillus spores. Incubation with crude catechins decreased the number of C botulinum and C butyricum spores but not B cereus spores. Furthermore, the effects of six catechin derivatives on spores were investigated. (−)‐Epicatechin gallate (ECg), (−)‐epigallocatechin (EGC), (−)‐epigallocatechin gallate (EGCg) and (+)‐gallocatechin gallate (GCg) were more effective in decreasing C botulinum and C butyricum spore numbers than (+)‐catechin (C) and (−)‐epicatechin (EC). The vegetative growth of C botulinum and B cereus was inhibited by crude extracts of the catechins. Specifically, purified GCg and EGCg inhibited the vegetative growth of C botulinum and B cereus. The inhibitory effect of ECg on B cereus was similar to that of GCg. However, toxin‐production by B cereus was not inhibited by catechin. Damage to the membrane of C butyricum spores by catechin derivatives was shown using fluorescent microscopy. This study shows that low concentrations of catechins, although requiring a long exposure time, inhibited the growth of bacterial spores. However, the effects of the purified derivatives of the catechins were not the same and GCg and EGCg were found to be the most potent. Spores that are generally resistant to many disinfectants were sensitive to catechins. Copyright © 2005 Society of Chemical Industry     

Purification and some properties of cholesterol oxidase stable in detergents from gamma-proteobacterium Y-134

Cholesterol oxidase (CHO) with high stability in detergents was found from an isolated strain, Y-134, belonging to the gamma-subclass of Proteobacteria. CHO production reached its maximum by incubation at 30 degrees C for 12 d. It was purified from cell-free extract prepared by mixing the cells with 0.4% Triton X-100. The absorption spectrum of the purified enzyme exhibited maxima at 274 and 410 nm, and a shoulder at 330 nm. The molecular mass was 115 kDa with two identical subunits of 58 kDa. The enzyme oxidized cholest-5-en-3beta-ol (cholesterol) and 5alpha-cholestan-3beta-ol (dihydrocholesterol) at a high reaction rate, and the K(m) value for cholesterol was 65 microM. The stability of the enzyme was higher than other CHOs in nonionic detergents with high values of hydrophilelipophile balance (HLB) such as Triton X-450 and sodium cholate. NH2-terminal sequence analysis showed a high similarity to CHO from Burkholderia cepacia, but not to CHOs from Streptomyces or Brevibacterium.     

New type of pressurized cultivation method providing oxygen for piezotolerant yeast

For efficient oxygen supply to pressurized culture, we developed a method using a highly pressurized membrane reactor with an air-saturated medium circulation system. The new method increased the cell growth of aerobic yeast approximately 20 folds larger than that in the case of using a conventional method.     

Gallic acid oxidizes Met residues in peptides released from bovine β-lactoglobulin by in vitro digestion

Phenolic compounds (PCs) are frequently present in foods. However, little is known about the effect of PCs on enzymatic digestion process of food proteins and their products. In this study, the effect of gallic acid (GA) on in vitro digestion of β-lactoglobulin (β-LG) was investigated as a model system for analysis of the interaction between PCs and food proteins. GA showed no effect on the initial rate of β-LG digestion. However, after 1.5 h of digestion, the observed degree of hydrolysis of β-LG was lower in the presence than in the absence of GA. The peptides released from β-LG were characterized by LC/IT-TOF-MS and thirty peptides were identified. In particular, four new peaks were obtained following in vitro digestion of β-LG in the presence of GA. Met(7), Met(24) and Met(145) in the peptides corresponding to these peaks were oxidized to methionine sulfoxide residues.     

Nucleotide sequences of alcohol acetyltransferase genes from lager brewing yeast,Saccharomyces carlsbergensis

The nucleotide sequences of alcohol acetyltransferase genes isolated from lager brewing yeast, Saccharomyces carlsbergensis have been determined. S. carlsbergensis has one ATF1 gene and another homologous gene, the Lg-ATF1 gene. There was a high degree of homology between the amino acid sequences deduced for the ATF1 protein and the Lg-ATF1 protein (75·7%), but the N-terminal region has a relatively low degree of homology. Southern analysis and contour-clamped homogeneous electric field analysis of Saccharomyces strains suggest that the ATF1 gene is located on chromosome XV in S. cerevisiae and that the Lg-ATF1 gene might originate from the ‘non-S. cerevisiae’ genome of S. carlsbergensis, which is similar to that of S. bayanus and S. pastorianus. The nucleotide sequence data reported in this paper will appear in the DDBJ, EMBL and GenBank data banks with the Accession Numbers D63449 (ATF1) and D63450 (Lg-ATF1).     

Catalytic Performance of Aged Rh/CeO2–ZrO2 for NO–C3H6–O2 Reaction Under a Stoichiometric Condition

The activity of Rh/CeO₂ for NO reduction by C₃H₆ was gradually deceased by mixing with ZrO₂ until 68 mol%. Rh supported on CeO₂–ZrO₂ with higher OSC was found to show lower catalytic activity. High OSC of CeO₂–ZrO₂ would probably stabilize the surface of Rh in oxidized state, resulting in low activity and low efficiency of C₃H₆ utilization for NO reduction. In situ FT-IR spectroscopy suggested that mononitrosyl species such as Rh(NO)^δ? and Rh(NO)^δ+ are reaction intermediates in the NO–C₃H₆–O₂ reaction over Rh/CeO₂–ZrO₂ catalysts.     

Metalloendopeptidase ADAM-like Decysin 1 (ADAMDEC1) in Colonic Subepithelial PDGFRα+ Cells Is a New Marker for Inflammatory Bowel Disease

Metalloendopeptidase ADAM-Like Decysin 1 (ADAMDEC1) is an anti-inflammatory peptidase that is almost exclusively expressed in the gastrointestinal (GI) tract. We have recently found abundant and selective expression of Adamdec1 in colonic mucosal PDGFRα⁺ cells. However, the cellular origin for this gene expression is controversial as it is also known to be expressed in intestinal macrophages. We found that Adamdec1 mRNAs were selectively expressed in colonic mucosal subepithelial PDGFRα⁺ cells. ADAMDEC1 protein was mainly released from PDGFRα⁺ cells and accumulated in the mucosal layer lamina propria space near the epithelial basement membrane. PDGFRα⁺ cells significantly overexpressed Adamdec1 mRNAs and protein in DSS-induced colitis mice. Adamdec1 was predominantly expressed in CD45⁻ PDGFRα⁺ cells in DSS-induced colitis mice, with only minimal expression in CD45⁺ CD64⁺ macrophages. Additionally, overexpression of both ADAMDEC1 mRNA and protein was consistently observed in PDGFRα⁺ cells, but not in CD64⁺ macrophages found in human colonic mucosal tissue affected by Crohn’s disease. In summary, PDGFRα⁺ cells selectively express ADAMDEC1, which is localized to the colon mucosa layer. ADAMDEC1 expression significantly increases in DSS-induced colitis affected mice and Crohn’s disease affected human tissue, suggesting that this gene can serve as a diagnostic and/or therapeutic target for intestinal inflammation and Crohn’s disease.     

Dual-Function Semaphorin 4D Released by Platelets: Suppression of Osteoblastogenesis and Promotion of Osteoclastogenesis

Effects of the antiosteoblastogenesis factor Semaphorin 4D (Sema4D), expressed by thrombin-activated platelets (TPs), on osteoblastogenesis, as well as osteoclastogenesis, were investigated in vitro. Intact platelets released both Sema4D and IGF-1. However, in response to stimulation with thrombin, platelets upregulated the release of Sema4D, but not IGF-1. Anti-Sema4D-neutralizing monoclonal antibody (mAb) upregulated TP-mediated osteoblastogenesis in MC3T3-E1 osteoblast precursors. MC3T3-E1 cells exposed to TPs induced phosphorylation of Akt and ERK further upregulated by the addition of anti-sema4D-mAb, suggesting the suppressive effects of TP-expressing Sema4D on osteoblastogenesis. On the other hand, TPs promoted RANKL-mediated osteoclastogenesis in the primary culture of bone-marrow-derived mononuclear cells (BMMCs). Among the known three receptors of Sema4D, including Plexin B1, Plexin B2 and CD72, little Plexin B2 was detected, and no Plexin B1 was detected, but a high level of CD72 mRNA was detected in RANKL-stimulated BMMCs by qPCR. Both anti-Sema4D-mAb and anti-CD72-mAb suppressed RANKL-induced osteoclast formation and bone resorptive activity, suggesting that Sema4D released by TPs promotes osteoclastogenesis via ligation to a CD72 receptor. This study demonstrated that Sema4D released by TPs suppresses osteogenic activity and promotes osteoclastogenesis, suggesting the novel property of platelets in bone-remodeling processes.     

Production of active recombinant eIF5A: reconstitution in E.coli of eukaryotic hypusine modification of eIF5A by its coexpression with modifying enzymes

Eukaryotic translation initiation factor 5A (eIF5A) is the only cellular protein that contains the polyamine-modified lysine, hypusine [N(ε)-(4-amino-2-hydroxybutyl)lysine]. Hypusine occurs only in eukaryotes and certain archaea, but not in eubacteria. It is formed post-translationally by two consecutive enzymatic reactions catalyzed by deoxyhypusine synthase (DHS) and deoxyhypusine hydroxylase (DOHH). Hypusine modification is essential for the activity of eIF5A and for eukaryotic cell proliferation. eIF5A binds to the ribosome and stimulates translation in a hypusine-dependent manner, but its mode of action in translation is not well understood. Since quantities of highly pure hypusine-modified eIF5A is desired for structural studies as well as for determination of its binding sites on the ribosome, we have used a polycistronic vector, pST39, to express eIF5A alone, or to co-express human eIF5A-1 with DHS or with both DHS and DOHH in Escherichia coli cells, to engineer recombinant proteins, unmodified eIF5A, deoxyhypusine- or hypusine-modified eIF5A. We have accomplished production of three different forms of recombinant eIF5A in high quantity and purity. The recombinant hypusine-modified eIF5A was as active in methionyl-puromycin synthesis as the native, eIF5A (hypusine form) purified from mammalian tissue. The recombinant eIF5A proteins will be useful tools in future structure/function and the mechanism studies in translation.     

Remarkable effect of ordered mesoporous carbon support in tantalum oxide-catalyzed selective epoxidation of cyclooctene

The olefin epoxidation is one of the most important reactions in chemical industry. Metal oxide supports often cause drawbacks in catalytic activity and selectivity, which has been overcome by introducing hydrophobic organic groups onto the oxide supports. The present study utilizes ordered mesoporous carbon (CMK-3 and CMK-1) as structurally defined hydrophobic catalyst support. Well-dispersed tantalum oxides supported on the ordered mesoporous carbon were prepared. Their application in catalytic epoxidation of cyclooctene demonstrates that the tantalum oxide catalysts on the ordered mesoporous carbon supports show higher performances than those of the catalysts supported on activated carbon and ordered mesoporous silica SBA-15.