PubMed Health⌕ Search

Biomedical subjects

N Seno

Publications and source records attributed to N Seno.

At least 73 records · Page 4Linked to original sources
PubMed1984

Tryptophan residues and the sugar binding site of potato lectin.

Potato lectin (Solanum tuberosum agglutinin, STA) was found to contain fluorescent tryptophan residues highly exposed to solvent. The binding of chitin oligosaccharides to STA induced fluorescence quenching, a shift of the fluorescence maximum to shorter wavelength, a decrease in the quenching constant of iodide ion and a decrease of the number of tryptophan residues modifiable by N-bromosuccinimide. The results suggested that one tryptophan residues is located at or near a sugar binding site of STA, and that its environment is altered from hydrophilic to relatively more hydrophobic upon interaction with specific sugars. The binding constants of STA with chitin oligosaccharides were determined by measuring the peak-trough heights in the fluorescence difference spectra induced by various concentrations of sugars. The inhibition constants of chitin oligosaccharides for the hemagglutinating activity of STA were obtained by the method of Pitts and Yang [(1981) Biochem. J. 195, 435-439] and the results were in good agreement with those obtained by the fluorescence spectral method. Standard and unitary free energy changes (delta G0 and delta Gu) and standard enthalpy changes (delta H0) were also obtained. These values decreased with sugar chain length up to at least the tetramer. Thus, it was assumed that there are at least 4 subsites, A, B, C, and D, in the sugar binding site of STA. The contributions to the binding energy (delta Gu) were -17.0, -12.6, -7.3, and -4.4 kJ/mol at subsites A, B, C, and D, respectively, and the bindings of chitin monomer (GlcNAc), dimer, trimer, and tetramer were assumed to occur at subsite A, AB, ABC, and ABCD, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Binding Sites↗
PubMed1984

Inhibition of the function of activated properdin by squid chondroitin sulfate E glycosaminoglycan and murine bone marrow-derived mast cell chondroitin sulfate E proteoglycan.

We compared the relative capacities of two over-sulfated glycosaminoglycans, heparin and chondroitin sulfate E, to alter the function of native properdin (nP) and activated properdin (aP) in the formation and stabilization of the amplification C3 convertase (C3b,Bb). Heparin was more active on a weight basis than chondroitin sulfate E in inhibiting the formation of C3b,Bb without or with nP, but had no influence on the decay of a pre-formed convertase, either unstabilized or stabilized with nP or aP. In contrast, chondroitin sulfate E was over 10-fold more active than heparin in preventing the formation of C3b,Bb in the presence of aP, and gave dose-related acceleration of decay of pre-formed C3b,Bb,aP but not of unstabilized or nP-stabilized pre-formed convertase. The inhibitory effect of both glycosaminoglycans on the formation of C3b,Bb in the presence of nP or aP was less when the number of C3b sites per target cell was increased. The preferential action of chondroitin sulfate E on the function of aP during the formation and decay of C3b,Bb,aP as compared to C3b,Bb,nP implies functional differences in the two forms of P even when they have been incorporated into C3b,Bb. The equal potency, when adjusted for uronic acid content, of chondroitin sulfate E proteoglycan isolated from the T cell-dependent, bone marrow-derived murine mast cell and of chondroitin sulfate E glycosaminoglycan from squid reveals that the linkage of the glycosaminoglycan to a peptide core does not diminish its regulatory action on the alternative complement pathway.

Animals↗
PubMed1983

Binding of fibronectin and its proteolytic fragments to glycosaminoglycans. Exposure of cryptic glycosaminoglycan-binding domains upon limited proteolysis.

Binding of intact plasma fibronectin and its proteolytic fragments to glycosaminoglycans immobilized on agarose beads was systematically compared at different ionic strengths. In low ionic strength buffer, intact fibronectin bound to heparin and high sulfated heparan sulfate, but not to low sulfated heparan sulfate, dermatan sulfate, chondroitin sulfates A and C, or hyaluronic acid. Fractionation of the thermolysin digest of fibronectin on the glycosaminoglycan-Sepharoses at low ionic strength revealed that three groups of fragments, i.e. Mr = 150,000-140,000, 24,000, and 16,000 (150K-140K, 24K, and 16K) fragments, were capable of binding to glycosaminoglycans with different specificities and affinities. The 150K-140K fragments exhibited the same specificities as intact fibronectin, binding only to heparin and high sulfated heparan sulfate. However, the 24K fragment bound not only to these two glycosaminoglycans but also to low sulfated heparan sulfate and other glycosaminoglycans as well. The 16K fragments were also capable of binding to most glycosaminoglycans with lower affinity than the 24K fragment. These results suggest that the binding sites in the 24K and 16K fragments are cryptic in the intact protein, but are exposed after limited proteolysis. The binding of fibronectin and its fragments to glycosaminoglycans is dependent on the ionic strength. At physiologic ionic strength, only heparin-Sepharose could bind intact fibronectin. Similarly, only heparin-Sepharose could bind the 150K-140K and 24K fragments, but not the 16K fragments, at the same ionic condition. Other glycosaminoglycan-Sepharoses did not retain significant amounts of any of the fibronectin fragments, suggesting that the affinity of plasma fibronectin and its fragments to heparan sulfate and other glycosaminoglycans, except heparin, is not strong enough to achieve stable mono- (or di-) valent binding under physiologic conditions.

Animals↗
PubMed1983

Purification and characterization of potato lectin.

Potato lectin (Solanum tuberosum agglutinin, STA), purified by affinity chromatography on tri-N-acetylchitotriose-Sepharose 6B, has Mr approximately 100,000, as estimated by gel filtration on Sephadex G-150 and is an aggregating system with a monomer Mr = 54,000, as estimated by sedimentation equilibrium analysis. Equilibrium dialysis showed that STA (dimer) has two binding sites for a specific sugar per molecule. STA has a high content of sugar, most of which is L-arabinose, and is rich in Hyp and Cys. On interaction with specific sugars, STA induced a UV difference spectrum having positive peaks at 292 and 285 nm characteristic of tryptophyl residues. The association constants with chitin oligosaccharides, determined from the intensities of the difference spectra at various concentrations of sugars, increased with increasing chain length of the sugar. Association constants obtained by frontal affinity chromatography of chitin oligosaccharides with STA-Sepharose were in good agreement with those obtained by difference spectra, whereas the association constants obtained by frontal affinity chromatography of STA with di- and tri-N-acetylchitotriose-Sepharose were much higher, presumably owing to the effect of multivalency of ligands. The CD spectra of STA in the far UV region indicate the presence of 40% of beta- and 60% of unordered form, and no alpha-helix conformation, which supports the structure suggested by the amino acid composition and the high content of sugar.

Carbohydrates↗
PubMed1983

Immunochemical and spectral studies on Vicia faba agglutinin.

Affinity chromatographic purification of Vicia faba agglutinin (VFA) was performed with a Sephadex G-150 column according to the method of Allen and Johnson [Biochim. Biophys. Acta (1976)]. VFA has 10 tryptophanyl residues per molecule on the assumption that its molecular weight is 50,000 daltons. Equilibrium dialysis with methyl a-D-[glucose-14C(U)]glucopyranoside showed that VFA has two sugar binding sites per molecule with a binding constant of 220 M-1. Upon interaction with specific sugars, VFA induced UV-difference spectra which are typical of the perturbation of tryptophanyl residues. Therefore, the binding constants of VFA with specific sugars could be calculated from the intensity changes in the difference spectra induced by various concentrations of the sugars. The results obtained were in good agreement with the results of hemagglutination inhibition assays. 3-O-Methyl-D-glucose had the highest binding constant (1.9 x 10(3) M-1) among the sugars examined. The binding constants of VFA with glucose, mannose, methyl a-D-glucopyranoside, methyl a-D-mannopyranoside, and maltose were 290, 900, 220, 500, and 220 M-1, respectively, which are lower than those of concanavalin A. VFA did not bind with mucopolysaccharides containing 2-acetamide-2-deoxy-a-, or -beta-D-glucopyranosyl residues, such as heparin, heparan sulfate, and hyaluronic acid. The far UV-CD spectrum of VFA was similar to that of concanavalin A.

Amino Acids↗
PubMed1983

Fluorescence spectral studies on the specific interaction between sulfated glycosaminoglycans and potato lectin.

On excitation at 280 nm, Solanum tuberosum agglutinin (STA) produced a fluorescence emission spectrum with a maximum at 347 nm, which is typical of tryptophanyl residues. The fluorescence emission maximum was shifted toward shorter wavelength and quenched by the addition of specific sugars. The changes were analyzed precisely and quantitatively by measuring the fluorescence difference spectra. This method required far smaller amounts of samples than UV-difference spectroscopy to obtain the binding parameters. The binding constants of chitin sulfate, keratan sulfate, and highly sulfated keratan sulfate were calculated to be 1.8 X 10(5) M-1, 3.4 X 10(5) M-1, and 5.2 X 10(5) M-1, respectively. The results indicate that consecutive and non-consecutive, alternating (1 leads to 4)-N-acetyl-beta-D-glucosaminyl residues in the glycosaminoglycans can interact freely with STA in spite of the existence of the sulfate groups at C-6 of the N-acetyl-D-glucosaminyl residues and extra sulfate groups at C-6 of the galactosyl residues linked with N-acetyl-6-O-sulfo-beta-D-glucosamine.

Glycosaminoglycans↗
PubMed1983

[Clinical significance of measurement of immunosuppressive acidic protein (IAP) in lung cancer].

Immunosuppressive acidic protein (IAP) was investigated in 37 patients with lung cancer. A positive rate of IAP in patients was 62.2% and it was higher than that in pulmonary benign diseases except infectious cases. Serum IAP levels increased in accordance with the progress of disease, but no relationship with histological findings was observed. No significant correlation was found between serum IAP levels and in vivo PPD skin test. However, in patients with more than 1000 micrograms/ml of serum IAP levels, higher proportion of patients with negative PPD skin test was observed, indicating the depressed immunity of these patients. From these results, it was suggested that the effects of treatment and prognosis could be predicted by pre-and post-operative IAP levels.

Adult↗
PubMed1983

A study on heifer mastitis in Japan and its causative microorganisms.

Survey and bacteriological examination were conducted on heifer mastitis in Hokkaido, the northern island of Japan over a period from 1976 to 1981. The disease occurred in heifers, mostly 13 to 18 months old, less than a half of which was pregnant in late summer or in August and September. Infection occurred predominantly in a front quarter than a rear one. Some microorganisms were isolated by the CO2 gas jet method from all the 74 secretions from the affected quarters of 67 heifers. Actinomyces pyogenes ( Corynebacterium pyogenes) was isolated from 49 secretions (66.2%), forty-six of which were involved in mixed infection with other microorganisms, including Peptococcus indolicus that was found in 41 secretions. Streptococcus dysgalactiae was isolated from 13 secretions, from nine of which were obtained pure cultures. The microorganisms harbored in secretion were much more closely associated simultaneously with A. pyogenes and P. indolicus than with A. pyogenes alone or a combination of A. pyogenes and any other microorganism than P. indolicus . This is the first report that P. indolicus was isolated from heifer mastitis in Japan. The "score" used for the expression of quality of milk secretion seemed to be useful for the clinical diagnosis of heifer mastitis. The disease in Hokkaido may be etiologically identical with summer mastitis found in the northern European countries.

Actinomyces↗
PubMed1982

Anticoagulant activity of dermatan polysulfates.

It has been found that dermatan polysulfates (DPS) I, II and III isolated from hagfish notochord, hagfish skin and shark skin, respectively, and chemically sulfated dermatan sulfate exhibit considerable anticoagulant activity in the "activated partial thromboplastin time (APTT)" system. On comparing the activities with the various compositions, including disaccharide units produced by the digestion with chondroitinase-ABC, it was shown that the activity of these dermatan polysulfates depends not only on the total sulfate content but also on the content of sulfated L-iduronic acid residues. The activity seemed to decrease for molecular weight of below 10,000. The effect of these dermatan polysulfates on th inactivation of the clotting enzymes, factor Xa and thrombin, by antithrombin II (AT-III) was also studied using chromogenic substrates for the assay of the enzyme activities. The dermatan polysulfates showed an inhibitory effect on thrombin-AT-III, as estimated by the APTT assay, in contrast with the effect on factor Xa-AT-III which was found to be very small.

Animals↗
PubMed1981

Interaction of sulfated glycosaminoglycans with lectins.

The sulfated glycosaminoglycans, such as keratan sulfate and chitin sulfate having 3-hydroxy free N-acetyl-beta-D-glucosaminyl residues as constituents, reacted with wheat germ agglutinin and Solanum tuberosum agglutinin by sugar-specific interaction. The glycosaminoglycans showed different inhibitory activities to the hemagglutination reaction of these lectins and keratan sulfate and its modified products formed insoluble complexes with both of the lectins at pH 7.0 in physiological saline solutions (0.15 M NaCl). S. tuberosum agglutinin was precipitated within a particularly narrow concentration range of keratan sulfate, and the formation of a soluble complex was observed by gel chromatography. These interactions were specifically inhibited by N,N'-diacetylchitobiose but not by 2 M NaCl. The specific interactions of the glycosaminoglycans with S. tuberosum agglutinin were confirmed by their ultraviolet difference spectra with two peaks at 285 and 298 nm attributable to the tryptophan residues in the binding site of the agglutinin. It was also found that S. tuberosum agglutinin and wheat germ agglutinin have different binding specificities. The presence of sulfate groups in either keratan sulfate or chitin sulfate did not interfere with their specific interactions with S. tuberosum agglutinin as strongly as with wheat germ agglutinin. The N-acetylneuraminic acid residues in keratan sulfate were found to be receptor sites for wheat germ agglutinin but not for S. tuberosum agglutinin.

Animals↗