A study of macromolecular diffusion through native porcine mucus

A diffusion chamber technique based on time-lag analysis for the estimation of effective diffusion coefficients of radiolabelled macromolecules of varying molecular weights through native mucus gel is reported. For all solutes studied, a reduction in effective diffusion coefficients was observed with a retardation of solute flux in both aqueus and mucus layers. Over the molecular weight range of solutes investigated (126–186 000 Daltons), a consistent effect of molecular weight was evident with regard to the retarding effect of mucus. No apparent or absolute molecular weight cut-off for macromolecular transfer was exhibited. However, at high molecular weights (>30 000 Daltons) the retardation was greatly enhanced. The results confirm that mucus can be regarded as a gel with finite pores, but that it does not constitute an absolute barrier to even high molecular weight solutes.     

Molecular weight of human alpha2-H-ferroglobulin subunits. Comparison with molecular weight of ferritin subunits]

alpha2 H globulin, a glycoferroprotein, was first demonstrated in the sera of patients with malignant diseases. This protein was isolated from cancerous human liver, and compared with ferritin, a ferroprotein showing some identical properties (presence of iron, high molecular weight, common antigenic determinants). However, physicochemical differences were observed between these two proteins. The study of protein dissociation was performed by polyacrylamide gel electrophoresis in sodium dodecyl sulfate after reduction by mercaptoethanol. A similar molecular weight of 19 000 is obtained for subunits of these two proteins. This value agrees well with the results obtained by other authors for ferritin.     

Molekulargewichtsbestimmung von Kalbsherzmyosin

Summary Sedimentation and diffusion coefficients, partial specific volume, intrinsic viscosity, ATP-ase activity and molecular weight of cardiac myosin from calf hearts were determined. The values agree well with the results ofMueller et al.⁴ for cardiac myosin of the dog, and are not essentially different from values reported for skeletal myosins.¹      

Persistence of infradian body weight cycles in castrated dormice (Glis glis)

Summary Male dormice were castrated at 2 phases of their infradian body weight cycles. No consistent changes were found in cycle period, amplitude, or absolute weights of the dormice following castration. Unlike other mammals, body weights of dormice appear unaffected by castration. Although both body weight and reproductive condition vary on an infradian basis, the changes in body weight appear to be programmed independently from changes in gonadal function.Acknowledgments. I would like to thank R. Melnyk, N. Mrosovsky, and J. D. Hallonquist for much helpful criticism and K. Lang and J. Kenyon for invaluable technical help. Research support was provided by a National Sciences and Engineering Research Council of Canada grant to N. Mrosovsky.     

Immunochemical evidence for the specific binding of putrescine to plasma proteins including fibronectin

Human plasma contains proteins capable of binding 14C putrescine by the action of Ca++ activated transglutaminase. These proteins have molecular weights from 32 to 220 K and above. One of these (with a molecular weight of 220 K) has been identified as fibronectin by the use of an antifibronectin antiserum. Evidence for a protein with a molecular weight identical to that of fibronectin has been obtained on PAGE analysis of the precipitate formed on incubating human serum with antipolyamine antiserum.     

Chymotrypsin-like and trypsin-like protease activities in the sea urchin (Hemicentrotus pulcherrimus) egg.

Proteolytic activities in extracts of sea urchin eggs were examined using SDS (sodium dodecyl sulphate)-polyacrylamide gels. In the unfertilized eggs, proteases were detected as bands corresponding to the molecular weights of 40 kD and 26 kD on the gelatin gel, and 35 kD and 30 kD on the casein gel. Using various protease inhibitors, it was found that 40 kD, 30 kD, and 26 kD are chymotrypsin-like proteases and that 35 kD is a trypsin-like protease. The activity of the 40 kD chymotrypsin-like protease was found to be almost completely lost after insemination.     

Chymotrypsin-like and trypsin-like protease activities in the sea urchin (Hemicentrotus pulcherrimus) egg

Proteolytic activities in extracts of sea urchin eggs were examined using SDS (sodium dodecyl sulphate)-polyacrylamide gels. In the unfertilized eggs, proteases were detected as bands corresponding to the molecular weights of 40 kD and 26 kD on the gelatin gel, and 35 kD and 30 kD on the casein gel. Using various protease inhibitors, it was found that 40 kD, 30 kD, and 26 kD are chymotrypsin-like proteases and that 35 kD is a trypsin-like protease. The activity of the 40 kD chymotrypsin-like protease was found to be almost completely lost after insemination.     

A comparative study of proteoglycans from bovine lung,trachea, tracheal mucosa,and aorta

Summary Proteoglycans were isolated from bovine lung, trachea, tracheal mucosa, and aorta by dissociative extraction with 4M guanidinium hydrochloride. Fractionation of these tissue extracts by cesium chloride density centrifugation and gel chromatography allowed the isolation from each extract of a high molecular weight fraction consisting mainly of proteochondroitin sulfate and hyaluronic acid.Acknowledgment. This work was supported by a National Heart, Lung, and Blood Institute grant to K. Ehrlich (HL21617).     

Molecular weight of lipovitellins during egg development in the crustacean amphipod Orchestia gammarella (Pallas)]

Egg lipovitellins of Orchestia gammarella tested by electrophoresis on gels of different acrylamide concentrations, following the procedure of Hedrick and Smith (1968), display a migration pattern identical to that of proteins with molecular weights of congruent to 3.2 x 10(5) (lipovitellin I) and congruent to 5.5 x 10(5) (lipovitellin II) respectively. Since their molecular weight remains constant during embryogenesis, the changes of their relative mobility in disc gels indicates alterations in their ionic charges.     

Guinea pig liver cytosol has an L-threonine deaminase activity distinct from L-serine deaminase]

Using sodium sulfate precipitation, "Sephadex G200" gel filtration and polyacrylamide gel electrophoresis, a L-threonine desaminase was demonstrated in the Guinea-Pig liver cytosol. This enzyme was separated from the guinea pig liver L-serine desaminase possessing an auxiliary activity on L-threonine substrate described by us in a previous work. The optimals for pH (7,1) and temperature (+ 55 degrees C) and the apparent molecular weight (134,000 + 20,000) were established.     

Compatible solutes of halophilic eubacteria: molecular principles,water-solute interaction,stress protection

Compatible solutes are best described as organic osmolytes responsible for osmotic balance and at the same time compatible with the cells' metabolism. A comprehensive survey (using HPLC and NMR methods) on halophilic/halotolerant eubacteria has revealed the full diversity of compatible solutes employed in nature. Molecular principles derived from the spectrum of compounds found in the bacterial world may be summarized as follows. Compatible solutes are polar, highly soluble molecules and uncharged at physiological pH. With the exception of proline (a proteinogenic amino acid) they are characterized as amino acid derivatives of the following types: betaines, ectoines, N-acetylated diamino acids and N-derivatized carboxamides of glutamine. Using nearinfrared spectroscopy we have also been able to demonstrate that compatible solutes are strong water-structure formers and as such probably excluded from the hydration shell of proteins. This preferential exclusion probably explains their function as effective stabilizers of the hydration shell of native proteins (protection against heating freezing and drying). Hence these typical products of halophilic eubacteria have a considerable potential as stabilizing/protecting agents on both molecular and whole-cell level. Thorough understanding of common structural principles and fundamental water-solute interactions will ultimately enable us to design novel highly efficient stress protectants and stabilizers of biomolecules.     

The effect of a gastric mucus barrier on the dynamic response of a pH electrode

Hydrogen ion mobility in gastric mucus has been found to be reduced to a greater extent than that hitherto suspected, though at low pH (less than 4) and in buffer this mobility increases. Mucus, at an optimized pH, may therefore protect the gastric mucosa from acid digestion by providing a diffusion barrier.     

Composition and functional role of the mucus layers in the intestine

In discussions on intestinal protection, the protective capacity of mucus has not been very much considered. The progress in the last years in understanding the molecular nature of mucins, the main building blocks of mucus, has, however, changed this. The intestinal enterocytes have their apical surfaces covered by transmembrane mucins and the whole intestinal surface is further covered by mucus, built around the gel-forming mucin MUC2. The mucus of the small intestine has only one layer, whereas the large intestine has a two-layered mucus where the inner, attached layer has a protective function for the intestine, as it is impermeable to the luminal bacteria.     

Influence of the enteric surface coat on the unidirectional flux of acetamide across the wall of rat small intestine

In vivo treatment of the jejunal mucosa with glycosidic enzymes seems to remove the enteric surface coat of the enterocyte. As a consequence, the mucosa-to-serosa unidirectional flux of acetamide increases remarkably. The glycocalyx probably represents a barrier to the diffusion of small hydrosoluble solutes.     

Darstellung und physikochemische Charakterisierung der Peptidketten des Tabakmosaikvirus

Summary Highly purified tobacco mosaic virus was split by different methods, the ribonucleic acid removed and the size of the protein sub-unit determined by sedimentation and diffusion. The value for the molecular weight of a polypeptide chain of the tobacco mosaic virus was calculated to be 17–18 000.     

Butanol extracts from myelin fragments. III. SDS-urea gel electrophoretic studies

Summary The butanol extracts from myelin fragments showing 5-HT binding capacity were studied by SDS-urea gel electrophoresis. 5 main bands were observed and their molecular weights were determined by the method of Ferguson relationship, and revealed that these extracts contained proteolipid protein, DM-20 and basic proteins. Furthermore, the reconstituted fraction with crude basic proteins and lipids showed the saturable binding capacity for C¹⁴·5-HT.Acknowledgment. We thank Prof. T. Iwamoto for his encouragement during the course of this study.     

Protection of rat gastric mucosa against ethanol injury by the new synthetic prostaglandin MDL 646

Oral administration to fasted rats of absolute ethanol produces extensive necrotic lesions of gastric mucosa as well as a massive leakage of proteins and mucus glycoproteins into gastric lumen. When the new synthetic prostaglandin MDL 646, belonging to the PGE1 series, is administered intragastrically (2 or 10 micrograms/kg) 30 min before ethanol administration, a significant protection of rat gastric mucosa against alcohol injury is observed.     

准固态电解质在染料敏化太阳能电池中的应用

综述了国内外染料敏化太阳能电池中准固态电解质的应用。按凝胶化的方法将准固态电解质分为有机小分子凝胶电解质、聚合物凝胶电解质和添加纳米粒子的凝胶电解质,并讨论了每种准固态电解质的特点及存在的问题。最后对准固态电解质的发展进行了展望。     

Electrophoretic profiles of proteins and glycoproteins of chick embryo fibroblasts during development]

The variations of proteins and glycoproteins of Chick embryo fibroblasts are studied during development. This investigation is carried out using polyacrylamide disc gel electrophoresis in SDS. Two glycoproteins of high apparent molecular weight (250,000 and 200,000) undergo quantitative modification: they increase from the 8th to 12th day of development and then remain unchanged to the 16th day. They are cell surface components as suggested by fluorescamine labelling and trypsin sensitivity. The results are discussed in terms of relationship between tumor- and embryo cells.