Search results for "WALL"
showing 10 items of 970 documents
Synthesis and Assembly of Wall Polymers on Regenerating Yeast Protoplasts
1983
Accumulation of chitin and glucan on S. cerevisiae and C. albicans protoplasts begins shortly after resuspension in the regeneration medium, and mannoprotein molecules also appear retained by the regenerating wall after 30–60 minutes in S. cerevisiae or after a longer lag period in C. albicans. Nevertheless, a considerable fraction of the synthesized mannoproteins, which in SDS-acrylamide gels exhibit a different pattern from that of wall mannoproteins of cells, are still released to the growth medium during at least eight hours. De novo synthesis of chitin synthase, but not of glucan synthase, is observed in S. cerevisiae from about 30 minutes after initiation of the regeneration process. …
Chitin: A Structural Biopolysaccharide
2009
Chitin is a naturally occurring fibre-forming polymer that plays a protective role in many lower eukaryotes similar to that of cellulose in plants. Chemically it is a long-chain unbranched polysaccharide made of N-acetylglucosamine residues; it is the second most abundant organic compound in nature, after cellulose. Taking into account the structural role played by chitin, its metabolism (synthesis and degradation) is essential for different morphogenetic events. Absent in vertebrates and plants, chitin represents a parasite-specific target for chemotherapeutic attack and also plays a role in host immune responses. Because of its abundance in nature and its properties, biotechnological appl…
Salt and fat contents influence the microstructure of model cheeses, chewing/swallowing andin vivoaroma release
2013
The effects of the lipid/protein ratio (20/28, 24/24, 28/20) and salt content of model cheeses were investigated simultaneously with respect to chewing behaviour, swallowing events and in vivo aroma release. Chewing parameters were measured by electromyography. Swallowing events were recorded manually. In vivo aroma release was investigated using nose-space on-line atmospheric pressure chemical ionisation-mass spectrometry. The values for chewing activity and time before swallowing were higher with lower lipid/protein ratios and lower salt contents, due to the greater mechanical resistance of the model cheeses. The corresponding microstructure was made up of smaller and more circular fat dr…
Wall mannoproteins of the yeast and mycelial cells of Candida albicans: nature of the glycosidic bonds and polydispersity of their mannan moieties.
1988
SUMMARY: Zymolyase released between 20 and 25% of the total protein from purified walls of yeast (Y) and mycelial (M) cells of Candida albicans. The material released contained 92% carbohydrate (86% mannose and 6% glucose) and 7:< protein. Over 85% of the carbohydrate was N-glycosidically linked to the protein and the rest (less than 15%) was linked O-glycosidically. Highly polydisperse, high molecular mass mannoproteins, resolved by electrophoresis as four defined bands in Y cells and two bands in M cells, had both types of sugar chains. A 34 kDa species found in both types of cells had a single 2.5 kDa N-glycosidically linked sugar chain and a 3 1.5 kDa protein moiety. Polydispersity in t…
Structural mannoproteins released by β-elimination fromCandida albicanscell walls
1994
Abstract Mild alkaline solutions (β-elimination), after removing the non-covalently bonded wall materials by hot SDS, released 13% and 26% of remaining wall proteins from mycelial and yeast cells of Candida albicans, respectively. When the β-elimination was carried out after digestion of the walls with chitinase, four-fold more proteinaceous materials were released from mycelium and a similar amount in yeast walls. The solubilized materials were shown to be highly polydisperse, and endo-glycosidase H reduced their polydispersity and molecular masses, revealing different electrophoretic patterns in yeast and mycelial cell walls. The solubilized mycelial proteins carried N-glycosidic sugar ch…
Functional analysis of the cysteine residues and the repetitive sequence ofSaccharomyces cerevisiaePir4/Cis3: the repetitive sequence is needed for b…
2003
Identification of PIR/CIS3 gene was carried out by amino-terminal sequencing of a protein band released by β-mercaptoethanol (β-ME) from S. cerevisiae mnn9 cell walls. The protein was released also by digestion with β-1,3-glucanases (laminarinase or zymolyase) or by mild alkaline solutions. Deletion of the two carboxyterminal Cys residues (Cys214-12aa-Cys227-COOH), reduced but did not eliminate incorporation of Pir4 (protein with internal repeats) by disulphide bridges. Similarly, site-directed mutation of two other cysteine amino acids (Cys130Ser or Cys197Ser) failed to block incorporation of Pir4; the second mutation produced the appearance of Kex2-unprocessed Pir4. Therefore, it seems th…
Secretion of Protein-bound Hydroxyproline from Moss Callus Cells
1988
Abstract A glycoprotein rich in hydroxyproline was found in wall preparations of callus cells of the moss Physcomitrium pyriforme Brid. It is apparently attached to the non-cellulosic polysaccharides of the wall, and the majority is extractable by boiling the wall fraction or by using a chaotropic salt at room temperature. A pulse-chase technique was used to study the transport of this protein to the wall. Cytochalasin B seems to inhibit its secretion from the callus cells. Some of this wall-associated protein is probably secreted from the cells into the medium. Electron microscopic evidence shows vesicular activity in the cytoplasm and secretion and incorporation into the wall layers (not …
Changes in cell wall pectin and pectinase activity in apple and tomato fruits duringPenicillium expansum infection
2006
Cell wall pectin degradation in apple and tomato fruit during infection by Penicillium expansum was investigated. In infected apple fruit, a significant decrease in the average molecular mass was observed in pectins extracted with CDTA and also in pectins extracted with Na2CO3. In tomato fruits, depolymerisation was also observed in both pectic fractions during infection, the major change being in the pectins extracted with Na2CO3. This pectin depolymerisation associated with P. expansum infection can be attributed to the action of pectinases; in apple fruit, a significant increase in polygalacturonase and pectin methylesterase was observed in infected fruits, although in tomato fruit the o…
Non-hydrolysable macromolecular constituents from outer walls of Chlorella fusca and Nanochlorum eucaryotum
1992
Abstract Many green microalgae possess a thin trilaminar outer wall (TLS) with a very high resistance to chemical degradation. TLS are known to play an important protective role in living cells. They are also selectively preserved during fossilization and thus provide a major contribution to the fossil organic matter of a number of sedimentary rocks. However, little information is available on TLS chemical structure. Examination of the TLS of Chlorella fusca (a lacustrine Chlorophycea) and of Nanochlorum eucaryotum (a recently discovered marine Chlorophycea) indicated that (i) they exhibit morphological features commonly observed in other green microalgae, (ii) their non-hydrolysable macrom…
Polysaccharide‐containing Cell‐wall Polymers of Archaea
2002
Introduction Historical Outline Chemical Structure Glutaminylglycan Heteropolysaccharide Methanochondroitin Pseudomurein S-Layer Lipoglycan Occurrence Functions Biochemistry Biosynthesis Biological Activity Molecular Genetics Biodegradation Methanochondroitin Pseudomurein Production (Producers, World market, Applications, Patents) Outlook and Perspectives Acknowledgements Keywords: glutaminylglycan; heteropolysaccharide; methanochondroitin; pseudomurein; S-layer (glyco-)protein; Archaea; cell envelope; cell-wall polysaccharides