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PubMed1976

Biosynthesis of yeast mannan. Independent formation of two carbohydrate moieties in the mannoprotein molecule.

The formation of two distinct types of carbohydrates moieties, beta-elminable saccharides attached to serine and/or threonine and of the polysaccharide portion of yeast mannan-protein was investigated using the particulate mannan synthetase from Saccharomcyes cerevisiae and GDP-[U-14C]mannose as mannosyl donor. The accumulated evidence obtained by following the kinetics of mannose incorporation into the different carbohydrate portions of mannoprotein, kinetics of thermal denaturation of enzymes responsible for their synthesis and by "pulse-chase" experiment where the change in the distribution of incorporated radioactivity was followed between the two carbohydrate moieties strongly suggests that the two carbohydrate portions in yeast mannoprotein are being synthesized independently, most probably by different sets of enzymes. At the same time, the obtained data show the beta-eliminable saccharides attached to serine and threonine in the peptide do not serve as precursors in the formation of polysaccharide part of mannoprotein.

Drug Stability↗
PubMed1976

Methylation and acetolysis of extracellular D-mannans from yeast.

Methylation-fragmentation analyses were conducted on a series of extra-cellular, yeast alpha-D-linked mannans representing six different structural types. D-Mannans of low degree of branching were produced by Hansenula capsulata strains and by species related to H. holstii, The former consisted primarily of (1 leads to 2)- and (1 leads to 6)-linked D-mannosyl residues; the latter, of (1 leads to 2)- and (1 leads to 3)-linked D-mannosyl residues. Although the remaining structural types were highly branched, each gave distinct methylation-patterns indicative of (1 leads to 6)-linked backbones to which are appended non-(1 leads to 6)-linked side-chains. Acetolysis studies were correlated with the methylation analyses, and the correlation demonstrated that each branched polymer possesses side chains of heterogeneous length.

Acetylation↗
PubMed1978

Lipid intermediates in the synthesis of the inner core of yeast mannan.

The synthesis by yeast microsomes of compounds that are probably dolichol-pyrophosphate derivatives containing N,N'-diacetylchitobiose and several mannose residues is described. However, the presence of monosaccharide residues other than N-acetylglucosamine and mannose has not been ruled out. The amount of the lipid derivatives synthesized was enhanced by the addition to the incubation mixture of an organic-solvent-soluble extract from rat liver known to contain dolicholpyrophosphate oligosaccharides. Incubation of these derivatives with yeast microsomes led to the transfer of about fifteen percent of their saccharide moieties to endogenous proteins. The oligosaccharides released from the dolichol derivatives by mild acid hydrolysis could serve as primers for the synthesis of a polysaccharide having the characteristics of mannan outer-chain. It is suggested that the dolichol-pyrophosphate derivatives described in this paper are intermediates in the synthesis of mannan inner core.

Carbohydrates↗
PubMed1979

Structure of the D-mannan and D-arabino-D-galactan in Crithidia fasciculata: changes in proportion with age of culture.

Cells of the insect flagellate Crithidia fasciculata contained mannan and arabinogalactan components, whose porportion varied with culture age, the former predominating during early stages, and the latter during the later stages of exponential growth and the deceleration phase. The mannan was a beta-D-(1 leads to 2)-linked D-mannopyranan. The arabinogalactan had a complex structure containing, in part, a beta-D-(1 leads to 3)-linked galactopyranose main-chain substituted in the 2 positions by single-unit D-arabinopyranose side-chains and with some unsubstituted units.

Animals↗
PubMed1979

Cross-reaction between the mycelial galactomannas of three Hormodendrum strains and the mannans of two Candida albicans strains of different serotypes, A and B.

Cross-reactivity between galactomannans of three representative Hormodendrum strains, H. pedrosoi IFO 6071, H. compactum IFO 6726, and H. dermatitidis IFO 6421, and the mannans of two Candida strains, C. albicans NIH A-207 (serotype A) and C. albicans NIH B-792 (serotype B), were investigated by means of agar-gel double diffusion, quantitative preciptin reaction, and passive cutaneous anaphylaxis. The following results were obtained. (i) Antisera to whole cells of three Hormodendrum strains were completely inactive in all in vitro antigen-antibody reactions to mannans of C. albicans NIH A-207 and C. albicans NIH B-792, whereas antisera to both C. albicans strains were found to be cross-reactive against the three Hormodendrum galactomannans. (ii) The results of cross-passive cutaneous anaphylaxis tests using guinea pigs sensitized with antiserum of three Hormodendrum and two Candida seemed to be consistent with those of the vitro assay. (iii) The reactivities of the corresponding acid-resistant core moieties of the three Hormodendrum galactomannas against two anti-C. albicans sera were nearly identical to those of the parent galactomannans in both in vitro and in vivo tests.

Animals↗
PubMed1979

Biosynthesis of yeast mannoproteins. Synthesis of mannan outer chain and of dolichol derivatives.

The Saccharomyces cerevisiae mutants affected in the structure of mannan outer chain were found to synthesize dolichol diphosphate-linked oligosaccharides identical in size to those of the wild type strain. The mannosyl transferases involved in the synthesis of the outer chain had an absolute requirement for manganese ions and were activated when enzymatic preparations were stored at 2 degrees C, whereas the transferases responsible for the formation of dolichol monophosphate mannose and dolichol diphosphate oligosaccharides were drastically inactivated from the onset of storage and required magnesium or manganese ions, the former being more effective than the latter. Both sets of enzymes could be separated by ion exchange chromatography. In vitro conditions that enhanced the synthesis of dolichol monophosphate mannose did not stimulate the incorporation of mannose residues into the outer chain. It is concluded that dolichol monophosphate mannose is not an intermediate in the synthesis of the outer chain and that this part of mannan and the dolichol diphosphate oligosaccharides are synthesized by different mannosyltransferases.

Carbohydrates↗
PubMed1978

[Structure of mannan of Candida guilliermondii H].

The mannan of Candida guilliermondii was acetolyzed and the seperation by gel chromatography gave five neutral fragments with the characteristic nuclear magnetic resonance spectra, mannose, mannobiose, mannotriose, mannotetraose, and mannopentaose. All oligosaccharide fragments were composed of mannose in alpha-linkage. Methylation analysis combined with gas chromatography-mass spectrometry demonstrated (1 leads to 6)-linked D-mannopyranose main chains with (1 leads to 2)-linked D-mannopyranose side chains.

Candida↗
PubMed1979

DNA sequence similarity, cell wall mannans and physiological characteristics in some strains of Candida utilis, Hansenula jadinii and Hansenula petersonii.

The physiological characteristics, proton magnetic resonance spectra of cell wall mannans, DNA base composition and DNA sequence similarity of some strains of Candida utilis, Hansenula jadinii and Hansenula petersonii were examined. It was found that C. utilis was not distinguishable from H. jadinii by any of these criteria. These findings show the close genetic relationship between C. utilis and its perfect form H. jadinii. In contrast, H. petersonii was found to differ from C. utilis and H. jadinii on account of insignificant DNA reassociation as well as a number of other properties.

Ascomycota↗
PubMed1978

alpha-Mannosidases of genera Aspergillus and Rhizopus. Activity and capacity to utilize Saccharomyces cerevisiae mannan of the best alpha-mannosidase producer Aspergillus flavus Link 69.

Strains of fungi imperfecti of genera Aspergillus and Rhizopus were tested for the ability to produce alpha-mannosidases. The most suitable alpha-mannosidase producer of a total of 20 strains under study was Aspergillus Ravus Link 69. The parameters studied during the cultivation included the growth rate expressed as cell dry weight, alpha-mannosidase activity of the extracellular medium with p-nitorphenyl alpha-D-mannopyranoside as substrate, and utilization of Saccharomyces cerebisiae mannan via its disappearance from the cultivation medium.

Aspergillus↗
PubMed1979

Purification of a mannan from Candida albicans which activates serum complement.

Candida species activate complement by the alternative pathway, induce leukocyte migration and, when applied epicutaneously, cause epidermal microabscesses of neutrophils in man and experimental animals. Complement activation by C. albicans appears to be a property of the cell wall. To biochemically identify the complement-activating constituent(s) of C. albicans, an ethyleneglycol extract of growth phase blastospores was prepared. Acid hydrolysis and neutral sugar analysis revealed mannose (82%), fucose (7%), and glucose (11%). The soluble, mannose-rich cell wall polysaccharide of C. albicans activates serum complement via the alternative pathway, induces neutrophil chemotaxis and is antigenically reactive with antisera to C. albicans. This constituent exhibits in vitro endotoxin-like activity as measured by Limulus lysate gelation, but is nonpyrogenic in rabbits. The extracts produced precipitin lines in double immunodiffusion studies against serum from patients with invasive candidiasis and rabbit antisera to mycelial and blastospore preparations of C. albicans, but not against normal serum. Thus, pathogenic properties and reactive phenomenon of C. albicans are in part attributable to a cell wall polysaccharide, mannan.

Animals↗
PubMed1976

[Assimilation of insoluble beta mannan by a strain of Streptomyces from the soil].

A strain of Streptomyces hydrolysing the insoluble beta (1 leads to 4) mannan has been isolated from a soil of palm plantation. The first step in the degradation of the polysaccharide is a random hydrolysis by a beta mannanase, leading to mannotetra-, mannotri- and mannobiose. Liberation of free mannose is never observed. The hydrolysing pattern of oligomannosides and of their reduced homologues has been studied and a transfert reaction is postulated. This mannanase behaves as a true endopolysaccharidase.

Glycoside Hydrolases↗