Conformational Change of a Natto Mucin in Solution

The mucin obtained from a natto sample was found to be composed of 58 % of γ-polyglutamic acid and 40% of polysaccharide. The ratio of l- and d-glutamic acid was determined to be 58:42 using l-glutamic acid decarboxylase. The weight- and z-average molecular weight were 2.08 × 10⁵ and 2.22 × 10⁵, respectively. The distribution curve of the sedimentation coefficient showed a small heterogeneity. The mucin molecule was considered to be randomly coiled at pH 5.0 ~ 8.8 and to be a rod-like molecule in the lower pH region.     

Effects of Sucrose and Citric Acid on the Viscometric Behavior of Aqueous Methylcellulose Solution

The flow of the mixture of methylcellulose (MC)—sucrose—citric acid—water was essentially thixotropic. The viscometric behaviors could be expressed by the power law, S = KDⁿ, where S was shearing stress and D rate of shear. The differential viscosity (ηd) of the mixture was strongly dropped by the addition of citric acid. Sucrose had the tendency to increase ηd of the mixtures except in the case of high sucrose concentration. From the results obtained, it has been concluded that citric acid tends to break the intermolecular hydrogen bonds of MC molecules, and that sucrose tends to keep the hydrogen bonds.     

Effect of Ca2+ Ions on the Viscometric Behavior of F-actin

Changes in the viscosity of the F-actin solutions which occur on addition of Ca²⁺ ions were investigated. The viscosity of F-actin decreased on addition of Ca²⁺ ions. The amount of Ca²⁺ ions needed to decrease the viscosity changed with pH of the solution, namely, 20~30 mm at pH 7, 15~20 mm at pH 6 and 5~10mm at pH 5.5. Other divalent cations had the same action on F-actin, but monovalent cations did not affect the F-actin viscosity even at the concentration as high as 1 m. Intrinsic viscosity of F-actin with and without Ca²⁺ions was 250 ±40 (ml/g) and 670 ±80 (ml/g), respectively. The cause of this viscosity change was discussed from the results of electron microscopic observation and light scattering measurements.     

Mucin glycoproteins in neoplasia

Mucins are high molecular weight glycoproteins that are heavily glycosylated with many oligosaccharide side chains linked O-glycosidically to the protein backbone. With the recent application of molecular biological methods, the structures of apomucins and regulation of mucin genes are beginning to be understood. At least nine human mucin genes have been identified to date. Although a complete protein sequence is known for only three human mucins (MUC1, MUC2, and MUC7), common motifs have been identified in many mucins. The pattern of tissue and cell-specific expression of these mucin genes are emerging, suggesting a distinct role for each member of this diverse mucin gene family. In epithelial cancers, many of the phenotypic markers for pre-malignant and malignant cells have been found on the carbohydrate and peptide moieties of mucin glycoproteins. The expression of carbohydrate antigens appears to be due to modification of peripheral carbohydrate structures and the exposure of inner core region carbohydrates. The expression of some of the sialylated carbohydrate antigens appears to correlate with poor prognosis and increased metastatic potential in some cancers. The exposure of peptide backbone structures of mucin glycoproteins in malignancies appears to be due to abnormal glycosylation during biosynthesis. Dysregulation of tissue and cell-specific expression of mucin genes also occurs in epithelial cancers. At present, the role of mucin glycoproteins in various stages of epithelial cell carcinogenesis (including the preneoplastic state and metastasis), in cancer diagnosis and immunotherapy is under investigation.     

Viscometric assay of bacterial alginase.

Equations defining the reaction of microbial alginase on commercial sodium alginate are presented with respect to the viscometric assay of enzyme activity. The negative log of K was found to be linearly related to the concentration of algin, where K is defined as the change in the reciprocal of relative viscosity with time. The negative log of K was also found to be linearly related to the amount of enzyme in reaction mixtures when the substrate concentration was held constant.     

Viscometric determination of carboxymethylcellulase in standard international units

A direct theoretical approach is described for using viscometric data to determine standard units of carboxymethylcellulase as recommended by the Commission on Enzymes. Application of the theory showed that under suitably defined conditions calculated units were directly proportional to the quantity of enzyme used for assay. When the theory was applied to a kinetic analysis of enzyme action, a linear relationship was obtained from a Lineweaver-Burk plot and allowed the Michaelis-Menten constant to be readily calculated. The theory can also be modified so that relative though arbitrary enzyme units can be obtained from one simple calculation. The method should be applicable to other depolymerases that cleave their substrate randomly.     

Mucin degradation in the intestine

Rat intestinal mucin was labelled biologically by intraperitoneal injection of radioactive amino acids and monosaccharides 3–6 h prior to killing, followed by isolation and purification of the mucin from mucosal scrapings. The labelled product was then introduced into intestinal segments of rats under ether anesthesia for periods up to 3 h, removed by washing and assessed for evidence of degradation. In segments containing the pancreatic ducts the total mucin precipitable by cetyltrimethylammonium bromide fell from 80% to 5% in 3 h. At 3 h, chromotography on Sephadex G-100 and Sepharose 4B revealed multiple products, including very small molecular weight fragments deficient in carbohydrate label. With the introduction of neomycin sulfate into the segments to reduce bacterial growth, only two products were found, one corresponding in size to the original mucin and one somewhat smaller, although still in excess of 200 000 daltons. These products occurred independently of the presence of the pancreatic ducts in the segments, and in chronically pancreatectomized rats. The smaller product could not be produced by incubation with trypsin or elastase. Both products were altered antigenically as compared with the original mucin. Both products also retained the same ratio of carbohydrate and protein label as the original. It is concluded that mucins undergo early degradative changes in the intestine which do not involve deglycosylation but which involve partial loss of antigenicity and a fall in molecular weight. The pancreas is not responsible for these changes.     

Functional myo-inositol catabolic genes of Bacillus subtilis Natto are involved in depletion of pinitol in Natto (fermented soybean)

Soybeans are rich in pinitol (PI; 3-O-methyl-D-chiro-inositol), which improves health by treating conditions associated with insulin resistance, such as diabetes mellitus and obesity. Natto is a food made from soybeans fermented by strains of Bacillus subtilis natto. In the chromosome of natto strain OK2, there is a putative promoter region almost identical to the iol promoter for myo-inositol (MI) catabolic genes of B. subtilis 168. In the presence of MI, the putative iol promoter functioned to induce inositol dehydrogenase, the enzyme for the first-step reaction in the MI catabolic pathway. PI also induced inositol dehydrogenase and the promoter was indispensable for the utilization of PI as well as MI, suggesting that PI might be an alternative carbon source metabolized in a way involving the MI catabolic genes. Natto fermentation studies have revealed that the parental natto strain consumed PI while a mutant defective in the iol promoter did not do so at all. These results suggest that inactivating the MI catabolic genes might prevent PI consumption, retaining it in natto for enrichment of possible health-promoting properties.     

The Binding of Bacillus natto Isolated From Natto to Heterocyclic Pyrolysates

The ability of natto, a fermented food, cells of bacterial strains isolated from natto,and viscous polymeric material (VPM) from natto to bind to pyrolysatesl such as Trp-P-1, Trp-P-2 and IQ (that are generated while cooking protein-enriched food and are potent mutagens) in the presence of an appropriate activation system was investigated. Strains of Bacillus nattobound 3-amino-1, 4-dimethyl-5H-pyrido(4,3-b)indole (Trp-P-1) and 3-amino-1-methyl-5H-pyrido(4,3-b)indole (Trp-P-2) effectively, bound 2-amino-3-methylinidazo(4,5f)quinoline (IQ) moderately, and bound 2-amino-6-methyl-dipyrido(1,2-a:32-d)imidazole (Glu-P-1) weakly. The VPM bound to Trp-P-1 and Trp-P-2 strongly, but not to IQ. The cell wall fraction bound very strongly to Trp-P-2, whereas the cytoplasmic fraction lacked mutagen-binding activity. The binding of freeze-dried cells to Trp-P-2 was pH dependent, and influenced by metal ions. The strongest binding occurred at pH 7.0, while the inhibition effect increased with the concentration of metal ions. In addition, natto itself possessed the ability to bind with heterocyclic amino acid pyrolysates.     

Viscometric characterization of pennisetin from pearl millet

Pennisetin, the alcohol soluble storage protein of pearl millet (Pennisetum americanum), was isolated in a homogeneous state. The intrinsic viscosity [n] of this protein was found to be in the range of 16.5-17.7 ml/g in 70% (v/v) aqueous ethanol. The [eta] changed marginally when temperature was increased from 20 to 70 degrees C and also in the presence of 10 mM NaCl. The data indicated that pennisetin was a rigid, rod shaped asymmetric hydrodynamic particle with molecular dimensions in the range of 301 x 14.4 A - 317.7 x 14.2 A. During denaturation with guanidine hydrochloride (Gdn.HCl), the intrinsic viscosity of pennisetin increased from 16 to 25ml/g with a mid point at 3.6 M of the denaturant. The native protein structure was unfolded in 6 M Gdn.HCl as shown by the exposure of aromatic amino acid residues buried in the native state and this transition was found to be reversible. The intrinsic viscosity of pennisetin in 5.9 M Gdn.HCl corresponded to Mr 25,000 which was comparable to that determined by SDS-PAGE.     

Mucin in cancer: a stealth cloak for cancer cells

Mucins are high molecular-weight epithelial glycoproteins and are implicated in many physiological processes, including epithelial cell protection, signaling transduction, and tissue homeostasis. Abnormality of mucus expression and structure contributes to biological properties related to human cancer progression. Tumor growth sites induce inhospitable conditions. Many kinds of research suggest that mucins provide a microenvironment to avoid hypoxia, acidic, and other biological conditions that promote cancer progression. Given that the mucus layer captures growth factors or cytokines, we propose that mucin helps to ameliorate inhospitable conditions in tumor-growing sites. Additionally, the composition and structure of mucins enable them to mimic the surface of normal epithelial cells, allowing tumor cells to escape from immune surveillance. Indeed, human cancers such as mucinous carcinoma, show a higher incidence of invasion to adjacent organs and lymph node metastasis than do non-mucinous carcinoma. In this mini-review, we discuss how mucin provides a tumor-friendly environment and contributes to increased cancer malignancy in mucinous carcinoma.     

Which characteristic of Natto: appearance, odor, or taste most affects preference for Natto

ABSTRACT: BACKGROUND: In Japan, consumption of Natto, a fermented bean dish, is recommended because of its high quality protein, digestibility in the gut and its preventive effect on blood clot formation due to high vitamin K content. However, consumption of Natto in Kansai and the Chugoku area (the western part of Honshu) is less than that in the other areas of Japan probably because of a "food related cultural inhibition". In this study, we determined which characteristic of Natto (appearance, odor or taste) most affect subjects' perception of sensory attributes by observation of brain hemodynamics in relation to subjects' preference for Natto. FINDINGS: In this experiment, we defined each subject's changes in brain hemodynamics as (+) or () corresponding to an increase or a decrease in total hemoglobin concentration after stimuli compared to that before stimuli. As a result, there was no relation between preference for Natto and change in brain hemodynamics by the stimuli of "looking at" or "smelling", while there was a significant relationship between preference and stimulus of "ingestion"; (+) : ()=21:15 in the subjects of the "favorite" group and (+): ()=30:7 in the subjects of the "nonfavorite" group (P=0.034). CONCLUSION: This result indicated that characteristic "taste" of Natto most affects preference for Natto.     

Solution Behavior and Activity of a Halophilic Esterase under High Salt Concentration

Background

Halophiles are extremophiles that thrive in environments with very high concentrations of salt. Although the salt reliance and physiology of these extremophiles have been widely investigated, the molecular working mechanisms of their enzymes under salty conditions have been little explored.

Methodology/Principal Findings

A halophilic esterolytic enzyme LipC derived from archeaon Haloarcula marismortui was overexpressed from Escherichia coli BL21. The purified enzyme showed a range of hydrolytic activity towards the substrates of p-nitrophenyl esters with different alkyl chains (n = 2−16), with the highest activity being observed for p-nitrophenyl acetate, consistent with the basic character of an esterase. The optimal esterase activities were found to be at pH 9.5 and [NaCl] = 3.4 M or [KCl] = 3.0 M and at around 45°C. Interestingly, the hydrolysis activity showed a clear reversibility against changes in salt concentration. At the ambient temperature of 22°C, enzyme systems working under the optimal salt concentrations were very stable against time. Increase in temperature increased the activity but reduced its stability. Circular dichroism (CD), dynamic light scattering (DLS) and small angle neutron scattering (SANS) were deployed to determine the physical states of LipC in solution. As the salt concentration increased, DLS revealed substantial increase in aggregate sizes, but CD measurements revealed the maximal retention of the α-helical structure at the salt concentration matching the optimal activity. These observations were supported by SANS analysis that revealed the highest proportion of unimers and dimers around the optimal salt concentration, although the coexistent larger aggregates showed a trend of increasing size with salt concentration, consistent with the DLS data.

Conclusions/Significance

The solution α-helical structure and activity relation also matched the highest proportion of enzyme unimers and dimers. Given that all the solutions studied were structurally inhomogeneous, it is important for future work to understand how the LipC''s solution aggregation affected its activity.     

唾液和泪液中主要黏蛋白MUC5B和MUC7协同互补功能

黏蛋白家族中MUC5B和MUC7是人体唾液和泪液中的两种主要黏蛋白成分,早期被认为在非特异性免疫应答、黏液构成以及组织功能的维护等方面发挥作用。近年来,它们的一些新功能如抗HIV、协助非黏蛋白功能的发挥等作用逐渐被发现,故其生理和病理意义也因传统观念的修正而得到扩充。由于MUC5B和MUC7在唾液和泪液中的存在方式并不完全相同,对它们在不同环境条件下功能的相似性、差异性和互补性的研究,具有重要的现实意义。     

Swimming Behavior Analysis Based on Bacterial Chemotaxis in Solution

Microrobots is playing more and more important roles for medical applications,such as targeting tumoral lesions for therapeutic purposes,Minimally Invasive Surgery (MIS) and highly localized drug delivery.However,energy efficient propulsion system poses significant challenges for the implementation of such mobile robots.Flagellated chemotactic bacteria can be used as an effective integrated propulsion system for microrobots.In this paper,we proposed a new type of propulsion method that is inspired by the motility mechanism of flagellated chemotactic bacteria in different pH gradients.The pH gradient field was established in solution through electrolysis method.The distribution of the pH values in solution was measured with pH indicator and analyzed with image processing technology,and the mechanism by which the pH values changed was also discussed.The swimming speed and direction of the bacteria were studied experimentally.Through analyzing the key parameters,such as stabilization time and electrode voltage,the optimal design of propulsion mechanism based on bacteria motion in the pH gradient field was proven.     

Mucin Dynamics in Intestinal Bacterial Infection

Background

Bacterial gastroenteritis causes morbidity and mortality in humans worldwide. Murine Citrobacter rodentium infection is a model for gastroenteritis caused by the human pathogens enteropathogenic Escherichia coli and enterohaemorrhagic E. coli. Mucin glycoproteins are the main component of the first barrier that bacteria encounter in the intestinal tract.

Methodology/Principal Findings

Using Immunohistochemistry, we investigated intestinal expression of mucins (Alcian blue/PAS, Muc1, Muc2, Muc4, Muc5AC, Muc13 and Muc3/17) in healthy and C. rodentium infected mice. The majority of the C. rodentium infected mice developed systemic infection and colitis in the mid and distal colon by day 12. C. rodentium bound to the major secreted mucin, Muc2, in vitro, and high numbers of bacteria were found in secreted MUC2 in infected animals in vivo, indicating that mucins may limit bacterial access to the epithelial surface. In the small intestine, caecum and proximal colon, the mucin expression was similar in infected and non-infected animals. In the distal colonic epithelium, all secreted and cell surface mucins decreased with the exception of the Muc1 cell surface mucin which increased after infection (p<0.05). Similarly, during human infection Salmonella St Paul, Campylobacter jejuni and Clostridium difficile induced MUC1 in the colon.

Conclusion

Major changes in both the cell-surface and secreted mucins occur in response to intestinal infection.     

具Sobolev-Galpern型湿气迁移方程解的渐近性和Blow-up

本文在文献[1,2,3,4,6]的基础上,对具有Sobolev-Galpern型土壤中湿气迁移方程和更一般的非线性拟抛物物型方程的初边值问题,在其解存在唯一的条件下,利用文献[5,7]的方法,深入探讨了相应问题解决的渐近性和爆破现象,得到了许多新结果。