PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Galactans”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1977

Idiotypes on galactan binding myeloma proteins and anti-galactan antibodies in mice.

Antibodies with specificity for beta1,6 linked D-galactoses were induced in mice by immunization with gum ghatti. Idiotypic antisera were prepared in rabbits and mice by immunization with 8 BALB/c IgA(k), beta1,6D-galactan binding myeloma proteins (beta6GALBMP). Two kinds of idiotypic sera were obtained: cross-specific sera that reacted with two or more beta6GALBMP but not other BALB/c myeloma proteins, and individual idiotypic sera that reacted with only the beta6GALBMP used in the immunization. Antibodies with specificity for beta1,6 linked D-galactans shared cross-specific idiotypes with beta6GALBMP. Only one of seven individual idiotypes associated with beta6GALBMP was found on galactan antibodies. Since all beta6GALBMP thus far have the same Vk and VH isotope composition the results indicate an extensive heterogeneity among galactan-binding immunoglobulins in BALB/c mice. It is speculated that some of this diversity may arise from somatic rather than germ line gene mutations.

Animals↗
PubMed1992

Molecular cloning of the rfb region of Klebsiella pneumoniae serotype O1:K20: the rfb gene cluster is responsible for synthesis of the D-galactan I O polysaccharide.

Previous chemical analyses identified two structurally distinct O polysaccharides in the lipopolysaccharide of Klebsiella pneumoniae serotype O1:K20 (C. Whitfield, J. C. Richards, M. B. Perry, B. R. Clarke, and L. L. MacLean, J. Bacteriol. 173:1420-1431, 1991). The polysaccharides were designated D-galactan I and D-galactan II; both are homopolymers of galactose. To begin investigation of the synthesis and expression of these O polysaccharides, we have cloned a 7.3-kb region of the chromosome of K. pneumoniae O1:K20, containing the his-linked rfbkpO1 (O-antigen biosynthesis) gene cluster. In Escherichia coli K-12 and Salmonella typhimurium, rfbkpO1 directed the synthesis of D-galactan I but not D-galactan II. The cloned rfbkpO1 genes did not complement a mutation affecting D-galactan II synthesis in K. pneumoniae CWK37, suggesting that another (unlinked) locus is also required for D-galactan II expression. However, plasmids carrying rfbkpO1 did complement a mutation in K. pneumoniae CWK43 which eliminated expression of both D-galactan I and D-galactan II, indicating that at least one function is common to synthesis of both polymers. Synthesis of D-galactan I was dependent on chromosomal galE and rfe genes. Hybridization experiments indicated that the rfbkpO1 sequences from different serotype O1 Klebsiella isolates showed some restriction fragment length polymorphism.

Cloning, Molecular↗
PubMed1976

Acute respiratory, circulatory and pathological changes in the calf after intravenous injections of the galactan from Mycoplasma mycoides subsp. mycoides.

Twenty of 28 calves, 10-12 weeks of age when given intravenous injections of the galactan from Mycoplasma mycoides subsp. mycoides, showed transient apnoea, increased pulmonary arterial and decreased systemic arterial blood pressures, and increased packed-cell volume. Necropsy revealed haemorrhages associated with alveolar ducts and vessel walls, areas of pulmonary oedema, usually associated with the haemorrhages, dilated airways and, in some, capillary thrombosis. Animals that had shown changes in blood pressure and respiration in response to a dose of galactan did not react to a second dose an hour later. One goat tested died, four lambs were mildly affected and a cat and several rats and guinea-pigs did not respond. It is suggested that the galactan released biogenic amines that produced the effects listed. Immunological mechanisms were discounted on the grounds that only a small amount of antigenic material was injected at the time the reaction occurred, and neither serological nor skin tests produced any evidence of prior sensitisation to the galactan or a similar substance. A relationship between reactivity to the galactan and susceptibility to the natural disease has been suggested. This, together with the pulmonary oedema found in galactan-treated calves and in natural lesions of contagious bovine pleuropneumonia (CBPP), and the possibility that contraction of blood vessels could be an initiating cause of thrombosis indicates the role that galactan may play in the pathogenesis of CBPP.

Animals↗
PubMed1977

Structure of the D-galactan isolated from garlic (Allium sativum) bulbs.

Hot-water extraction of defatted garlic-bulbs yielded a mixture of polysaccharides containing a D-galactan, a D-galacturonan, an L-arabinan, a D-glucan, and a D-fructan. A trace of L-rhamnose was also detected in the polysaccharide hydrolyzate. The pectic acid was partially removed by precipitation with aqueous calcium chloride; from the remaining polysaccharide mixture, a pure D-galactan containing 97.3% of D-galactose was isolated by fractional precipitation and repeated chromatography through a column of DEAE-cellulose. Methanolysis and hydrolysis of the permethylated D-galactan yielded 2,3,4,6-tetra-, 2,3,6-tri-, and 2,3,di-O-methyl-D-galactose in the molar proportions of 1:2:1. On periodate oxidation, the D-galactan reduced 1.18 molar equivalents of the oxidant per D-galactosyl residue, and liberated one molar equivalent of formic acid per 4.13 D-galactosyl residues. Smith degradation of the D-galactan was also conducted. From these results, a structure has been assigned to the repeating unit of the D-galactan.

Galactose↗
PubMed1992

Structural diversity among sulfated alpha-L-galactans from ascidians (tunicates). Studies on the species Ciona intestinalis and Herdmania monus.

Sulfated polysaccharides occurring in the tunic of different species of ascidians differ markedly in electrophoretic pattern and chemical composition. A purified sulfated alpha-L-galactan from Herdmania monus was studied using methylation analysis and NMR spectroscopy; it is composed mainly of 3-sulfated 4-linked alpha-L-galactopyranoyl units. This is the first description of a homo-polymer of sulfated alpha-L-galactose. In contrast, the sulfated L-galactan from Ciona intestinalis shows marked structural heterogeneity and a low sulfate content. These data indicate unusual structural diversity among sulfated L-galactans from different species of ascidians.

Animals↗
PubMed1978

Evaluation of oral iron galactan as a method of iron supplementation for intensively housed sucking piglets.

Iron supplementation of piglets with oral galactan given as a single dose within 24 hours of birth was evaluated in a series of on farm trials. The growth rate of piglets receiving this treatment was faster than that of piglets receiving single injections of iron dextran or iron galactan at 3 days of age, or ferrous sulphate crystals orally at weekly intervals. Mean values for red cell parameters of oral iron galactan supplemented piglets at 2 to 4 weeks of age were lower than those of injected piglets but there was no clinical evidence of anaemia in any of the piglets.

Administration, Oral↗
PubMed1978

Structure of a beta-galactan isolated from the nuclei of Physarum polycephalum.

A sulfated and phosphorylated beta-D-galactan ([alpha]D+8degrees) was isolated from the nuclei of the acellular slime mould Physarum polycephalum. The polysaccharide was isolated from cesium chloride gradients during the preparation of ribosomal DNA and purified. The purified galactan contained 89% galactose, 2.5% phosphate and 9.6% sulfate groups and had an average degree of polymerisation of 560. Periodate degradation and permethylation studies indicated the presence of mainly (1 leads to 4)-, but also of (1 leads to 3)-, and (1 leads to 6)-linked galactose units with one branch every 13 units. These results suggested that the intranuclear galactan, apart from its higher sulfate content, is similar to the extracellular polysaccharide produced by P. polycephalum.

Chemical Phenomena↗
PubMed1976

Different glycosubstances and galactans in the albumin gland and eggs of Achatina fulica.

In saline extracts from the eggs and the albumin gland of the snail Achatina fulica 3 different forms of glycosubstances have been found by using heterophile precipitins from different sources: 1. An alkali-stable galactan reacting with the anti-galactans from Axinella polypoides sponge and from the clam Tridacna maxima (Tridacnin) and with Concanavalin A. 2. Another glycosubstance giving cross-reactions with a second precipitin from Axinella polypoides, with the lectin from Ricinus communis, with murine myeloma anti-galactan, with pneumococcus Type XIV antiserum and with Tridacnin. 3. The second precipitin from Axinella polypoides detects a third glycosubstance, which reacts with the lectins from Abrus precatorius and wheat germ (Triticum vulgaris).

Animals↗
PubMed1978

Ultrastructural localization of beta-D-galactan in the nuclei of the myxomycete Physarum polycephalum.

The acellular slime mold Physarum polycephalum produces an extracellular sulfated and phosphorylated beta-D-galactan which was recently isolated from the nuclei of this organism. This polysaccharide has now been localized in the nuclei of P. polycephalum by electron microscopy using a specific "sandwich" technique: thin sections of P. polycephalum microplasmodia were incubated with the Ricinus communis lectin specific for D-galactose residues. The bound lectin was then localized with gold granules labeled with a galactose-terminated glycoprotein (desialylated ceruloplasmin). The galactan was found in the nuclei mainly associated with chromatin and, also, but to a smaller extent, in the cytoplasm and in some vacuoles. The specificity of the method was assessed by marking under the same condition the galactomannan present in the cell wall of the yeast Schizosaccharomyces pombe.

Cell Nucleus↗
PubMed1976

Blood group H like activity in crude preparations of bovine lung galactan.

In crude preparations of bovine lung galactan blood group H-like activity, which does not occur on bovine red cells, has been detected with heterophile anti-H-like reagents from different origin. These H-like receptors, associated with pneumococcus type XIV cross-reactivity, belong to a glycoprotein fraction and not to the galactan itself.

Agglutination↗
PubMed1975

Anti-galactan activity in Tridacna maxima (Röding) haemolymph. Calcium dependence of the haemagglutinins and precipitins.

A powerful natural agglutinin with haemagglutinating and precipitating properties has been found in the haemolymph from the elongate clam Tridacna maxima (Röding). The agglutinin shows anti-galactan properties and reacts with a variety of bacteria-, plant-, invertebrate- and vertebrate-derived galactans, glycopeptides and polysaccharides. Previous studies which showed that the agglutinin-combining sites were inhibited by 2-acetamido-2-deoxy-D-galactose and D-galactose also revealed some anomalies in the reactions of the agglutinin with different saccharide-containing macromolecules. In an attempt to resolve these anomalies, the present study further examines the precipitating and haemagglutinating properties of the agglutinin and illustrates a requirement of the agglutinin for Ca2+. The ability of the T. maxima agglutinin to precipitate with structures containing terminal beta-linked 2-acetamido-2-deoxy-D-galactopyranosyl or D-galactopyranosyl groups suggests that the Tridacna haemolymph and purified lectin will find considerable application in the study of many biologically important carbohydrates.

ABO Blood-Group System↗
PubMed1978

Purification and characterization of a galactan-reactive agglutinin from the clam Tridacna maxima (Röding) and a study of its combining site.

1. A beta-galactosyl-binding lectin was purified from the haemolymph of the clam Tridacna maxima by affinity chromatography using polylecyl larch galactan, D-galactosamine coupled to epoxy-activated Sepharose or acid-treated Sepharose. Elution with N-acetyl-D-galactosamine or lactose displaced the bound lectin, which appeared homogeneous by sedimentation analysis. On immunoelectrophoresis at pH8.6 and against rabbit antisera to crude T. maxima haemolymph, the lectin gave one precipitin arc in the alpha-region. 2. On a alkaline polyacrylamide disc gels, one lightly stained band and a broad diffuse band were seen close to the cathode. Ioselectric focusing in solution revealed two peaks of pI4.05 and 4.25 and a shoulder, pI4.0, whereas at least three bands close together (pI3.9-4.3) were seen after electrofusing in gel. 3. The agglutinin is a glycoprotein with a mol.wt. of 470300 +/- 20000. Amino acid analysis revealed no methionine and a significant amount of half-cystine residues. 4. Tridacna lectin is a metalloprotein requiring Ca2+ for its haemagglutinating and precipitating activities. 5. In haemagglutination studies the agglutinin exhibited a broad pH optimum (4.8-10.6). 6. Polysaccharides and glycoproteins with terminal non-reducing beta-D-galactosyl residues reacted with the lectin to form precipitates both in gel and in solution. Inhibition experiments showed that N-acetyl-D-galactosamine was the best inhibitor of the agglutinin combining sites, followed by p-nitrophenyl beta-D-galactoside, methyl beta-D-galactoside, D-galactosamine and 60O-beta-D-galactopyranosyl-D-galactopyranose. On a molar basis, N-acetyl-D-galactosamine was 20-fold more active than D-galactose and nearly 10-fold more inhibitory than D-galactosamine. 7. Circular-dichroism studies showed that the lectin contains a relatively high proportion of beta-structure. 8. Mercaptoethanol treatment of the agglutinin followed by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis revealed subunits with approx. mol.wts. of 10000, 20000 and 40000.

Agglutinins↗
PubMed1979

Structural evidence for independent joining region gene in immunoglobulin heavy chains from anti-galactan myeloma proteins and its potential role in generating diversity in complementarity-determining regions.

We have determined the variable region sequences of four heavy chains from beta(1-6)D-galactan-binding myeloma proteins. Two of these proteins are identical to position 100 which is located in the third complementarity-determining region (CDR-3). The remaining two differ at a total of 8 positions over the first 100 amino acids, and all of the differences can be explained by single-base mutations at the DNA level. When an assessment is made of the protein segment following CDR-3, which has been termed "J segment" or "FR4," a completely different pattern of variation is observed. The J segments from the four proteins can be divided into two sets. Members of each set share a series of linked amino acids not found in members of the alternative set. The two proteins identical to position 100 have J segments from the two different sets, suggesting that recombination has occurred between V and J genes. An examination of the CDR-3 sequences from the four heavy chains reveals substitutions at positions 100 and 105. Gly is found at 100 in two of the proteins and His in the remaining two. In the two proteins with Gly-100, the following J sequence is limited to one of the two sets of J segments defined by linked amino acids. Similarly, the two heavy chains with His-100 have J segments from the second set. Thus, at the protein level an apparent association is seen between CDR-3 and J segment. If CDR-3 should be found linked to J segment at the DNA level, a new mechanism would be introduced for increasing antibody diversity by recombining various CDR-3 plus J genes with genes coding for the remainder of the variable region. Alternatively, if CDR-3 were coded for by the V gene, then the recombination of V with J may provide an opportunity to introduce mutations in CDR-3. In this case the linkage of amino acids in CDR-3 and the J segments would suggest that recognition signals are used such that certain V genes only pair with a given J gene.

Amino Acid Sequence↗
PubMed1979

Crystal structure of galactan-binding mouse immunoglobulin J539 Fab at 4.5-A resolution.

An electron-density map of the mouse galactan-binding immunoglobulin J539 (IgA2,kappa) Fab has been calculated to a resolution of 4.5 A by the method of heavy atom isomorphous replacement with four derivatives. The map has been interpreted with the aid of a computer program which systematically searched for the best fit between the electron-density map and the known coordinates of individual immunoglobulin domains. The quaternary structure of J539 Fab at this resolution appears similar to that of another mouse immunoglobulin, IgA2,kappa Fab, McPC603. The model coordinates for J539 Fab should allow us to proceed directly to a high-resolution structure determination without further heavy atom isomorphous replacement.

Animals↗
PubMed1976

The oxidation of terminal D-galactofuranose residues of a galactan and a glycoprotein by a D-galactose oxidase preparation from Dactylium dendroides.

A galactan, isolated from the unicellular organism Prototheca zopfii, and a glycoprotein from a hyphal cell-wall fraction of the fungus Pithomyces chartarum have been oxidised by a D-galactose oxidase preparation from Dactylium dendroides. The oxidised polymers were subsequently reduced with sodium borotritide. The site of oxidation was identified as C-6 of non-reducing D-galactofuranosyl residues in both polymers.

Alcohol Oxidoreductases↗
PubMed1975

The galactan sulphate of the red alga Polysiphonia lanosa.

The structure of the galactan sulphate of P. lanosa has been established by a combination of methylation, treatment with alkali, and partial methanolysis of the alkali-treated polysaccharide to give derivatives of agarobiose. The polysaccharide belongs to the agar class, in which 3-linked derivatives of beta-D-galactose alternate with 4-linked derivatives of alpha-L-galactose in a repeating sequence. In addition to D-galactose itself, the 3-linked units include 6-O-methyl-D-galactose, D-galactose 6-sulphate, and a hitherto unreported unit, 6-O-methyl-D-galactose 4-sulphate. The 4-linked units include L-galactose 6-sulphate, 2-O-methyl-L-galactose 6-sulphate, and 3,6-anhydro-L-galactose.

Galactose↗