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321.
P. Mullainadhan L. Renwrantz 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1989,159(4):443-452
Summary The hemolymph ofHelix pomatia contains a weak agglutinating activity. This lectin concentration was calculated to be about 1.8 g·ml–1. Among the different red blood cells tested, pronase-treated sheep erythrocytes were found to be the most suitable indicator cells. Their agglutination could be inhibited by GalNAc and GlcNAc. The serum agglutinin was isolated by affinity chromatography using Sephadex G-200 as the matrix. It exhibited a single band in discontinuous PAGE. In the presence of SDS, subunits of 27000 daltons were obtained which, after addition of 2-mercaptoethanol, partly dissociated into 13000-dalton subunits. The biochemical properties observed were compared with those of the well-known blood group A-specific lectin from the albumin gland ofH. pomatia.Abbreviations
GalNac
N-acetyl-galactosamine
-
GlcNAc
N-acetyl-glucosamine
-
SDS
sodium dodecylsulfate 相似文献
322.
Gel filtration of jack fruit seed agglutinin in 6 M guanidine hydrochloride confirmed our earlier report that the native 39.5-kDa protein was a tetramer of identical noncovalently associated 10-kDa subunits. Binding studies by the fluorescence quenching method using 4-methylumbelliferyl -D-galactoside as well as equilibrium dialysis using p-nitrophenyl -D-galactoside indicated only two binding sites per tetramer. This behaviour resembles the half-of-the-sites reactivity in certain enzymes and is discussed in view of the small subunit size. 相似文献
323.
Root tips of wheat, rye, barley and rice seedlings contain lectins which are identical to the respective embryo lectins with respect to their molecular weight, sugar-specificity and serological properties. Using in vivo labelling techniques, it could be demonstrated that lectin is synthesized de novo in these tissues. The presence of lectin mRNA in seedlings was confirmed by in-vitro synthesis of lectin in root-tip extracts. Lectin synthesis occurs both in primary and first adventitious roots and is confined to the apical part (2mm) of the root. As seedling development proceeds, lectin synthesis in root tips gradually decreases. Adventitious roots of adult (five to six months old) wheat, rye and barley, but not rice, plants also contain lectins which are indistinguisable from the embryo lectins by the above-mentioned criteria. These lectins are synthesized in vivo in isolated root tips (5 mm) with labelled cysteine and in vitro in cell-free extracts prepared from root tips. Synthesis of lectin in roots of adult plants is also confined to the apical (2 mm) tip of the roots. At the molecular level, root lectin synthesis is very similar to that in embryos. All root lectins are synthesized as 23 000-Mr precursors which are post-translationally converted into the mature 18 000-Mr polypeptides. The observation that seedling roots and adventitious roots of six-month-old plants actively synthesize lectins strongly indicates that lectin genes are expressed in these tissues. In addition, since the root lectins are indistinguishable from the embryo lectins, we postulate that the same lectin genes are expressed.Abbreviations ABA
abscisic acid
- SDS-PAGE
sodium dodecyl sulphate-polyacrylamide gel electrophoresis
- WGA
wheat-germ agglutinin 相似文献
324.
325.
Alexandre H. Sampaio David J. Rogers Clive J. Barwell Silvana Saker-Sampaio Francisco H. F. Costa Márcio V. Ramos 《Journal of applied phycology》1998,10(6):539-546
Ptilota serrata has been shown previously to contain a lectin (PSL) which is non-specific for human blood groups. We report here a new isolation
procedure for PSL using a single step affinity chromatography technique on cross-linked guar gum and further characterisation
studies. PSL was inhibited by galactose and its derivatives. The carbohydrates o-nitrophenyl-N-acetyl-α-D-galactoside, p-nitrophenyl-N-acetyl-β-D-galactoside and lactose were strong inhibitors. The glycoproteins porcine stomach mucin, asialo bovine mucin and asialofetuin
were also inhibitory. The Mr of PSL, determined by gel filtration, was 55,470. SDS-PAGE revealed one single protein band with
Mr of 18,390, indicating the native protein to be a trimer of apparently identical subunits. PSL was shown to contain large
amounts of acidic and hydroxyl amino acids but low in basic amino acids.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
326.
Fu-Yue Zeng Alberto Benguría Sabine Kafert Sabine André Hans-J. Gabius Antonio Villalobo 《Molecular and cellular biochemistry》1995,142(2):117-124
Biosignalling via lectins may involve modulation of protein kinase activities. This aspect of the biological action of mammalian and plant lectins has been investigated for their effect on the activity of the isolated epidermal growth factor receptor (EGFR). The constitutive tyrosine kinase activity of the epidermal growth factor receptor from rat liver, isolated by calmodulin-affinity chromatography, was activated by concanavalin A (ConA), and wheat germ agglutinin (WGA) to a similar extent as the measured enhancement induced by EGF. In contrast, two mannose-specific lectins, the mannan-binding protein (MBP) and serum amyloid P component (SAP), isolated from human serum, have inhibitory effects, both in the absence and presence of EGF. The differential effects of these lectins were tested using as phosphorylatable substrates a co-polymer of glutamic acid-tyrosine, as well as calmodulin. However, two galactoside-specific lectins, the laminin-binding -galactoside-binding 14 kDa lectin, isolated from bovine heart (14K-BHL), and the /-galactoside-binding lectin, isolated from mistletoe (Viscum album L.) leaves (VAA), do not inhibit the EGFR tyrosine kinase activity. The sugar dependence of the lectin-mediated action was studied by inhibition assays. Mannose and a mannose-containing neoglycoprotein prevent the activating effect of ConA, and N-acetyl-D-glucosamine partially prevents the activation produced by WGA. However, mannose and mannose-containing neoglycoprotein were ineffective to reduce the inhibitory effect of MBP or SAP. Although the response to binding of ConA and WGA was different to that of MBP or SAP with respect to the tyrosine kinase activity of the EGFR, it should be noted that the four lectins inhibited the binding of [125I]EGF to its receptor with similar efficiency.Abbreviations EGF
epidermal growth factor
- EGFR
epidermal growth factor receptor
- ConA
concanavalin A
- MBP
mannan-binding protein
- SAP
serum amyloid P component
- WGA
wheat germ agglutinin
- 14K-BHL
bovine heart 14 kDa lectin
- VAA
Viscum album L. (mistletoe) agglutinin
- EGTA
[ethylenebis(oxyethylenenitrilo)]-tetraacetic acid; poly(Glu:Tyr)-co-polymer of L-glutamic acid and L-tyrosine
- Hepes
4-(2-hydroxyethyl)-1-piperazinethanesulfonic acid
- Tris
tris(hydroxymethyl)-aminomethane
- DSS
suberic acid bis(N-hydroxy-succinimide ester)
- PMSF
phenylmethanesulfonyl fluoride
- Man
mannose
- Gal
galactose
- BSA
bovine serum albumin
- Man-BSA
neoglycoprotein containing -D-mannose
- Lac-BSA
neoglycoprotein containing -lactose
- Gal-BSA
neoglycoprotein containing galactose 相似文献
327.
K. S. Powell A. M. R. Gatehouse V. A. Hilder E. J. M. Van Damme W. J. Peumans J. Boonjawat K. Horsham J. A. Gatehouse 《Entomologia Experimentalis et Applicata》1995,75(1):61-65
Insect feeding trials were carried out to determine the effects of a range of mannose-specific lectins on third instar nymphs of the rice brown planthopper (BPH), Nilaparvata lugens. Stål. Dose response curves show that Galanthus nivalis agglutinin (GNA) has the strongest toxic effect of the lectins tested, and is effective at concentrations considerably lower than those previously reported. Narcissus pseudonarcissus agglutinin (NPA) and Allium sativum agglutinin (ASA) exhibit a significant antimetabolic effect towards the insect but were less effective (on a molar basis) than GNA. LC50 values for GNA, NPA and ASA are approximately 4 μM, 11 μM and >40 μM respectively. These mannose-specific lectins are serologically identical, but differ in the number of subunits per protein molecule; ASA is a dimer, NPA is a trimer and GNA is a tetramer. The results obtained support the hypothesis, that the effectiveness of the mannose-binding lectins as antimetabolites is determined by the number of subunits per molecule. Two N-acetylglucosamine binding lectins, the dimeric Oryza sativa agglutinin (OSA) and the monomeric Urtica dioica agglutinin (UDA), were also tested but at a concentration of 0.1% w/v exhibited no significant antimetabolic effect towards BPH, although the related lectin wheatgerm agglutinin (WGA) has previously been demonstrated to be toxic towards the insect. 相似文献
328.
Surface changes of hemocytes from the migratory grasshopper,Melanoplus sanguinipes (Fab.), following wounding and/or infection withBeauveria bassiana (Bals.) Vuillemin were assessed using fluorescein labelled wheat germ agglutinin (WGA) and concanavalin A (Con A). Binding
was observed on outer wall of hemocytes when either Con A or WGA conjugates were tested. After infection there was an increase
in the percentage of hemocytes which bound to WGA and which remained so for 24 h. However, after wounding this increase in
binding subsided after only 1 h. Furthermore, it was found that the increase in WGA-binding occurred within the first 15 min
of wounding or infection. In addition, ConA binding in males only increased 3-fold in fungus-injected insects within 1 h of
treatment and remained high for 24 h. These results indicated the presence of mannose (and/or glucose) residues (Con A specificity)
and N-acetyl-D-glucosamine residues (wheat germ agglutinin; WGA specificity) on outer wall surfaces of the hemocytes. The
implications of these results in the immune response ofM. sanguinipes to infection withB. bassiana are discussed. 相似文献
329.
AMOS FRISCH WOLFGANG BESSLER HANS JOACHIM LIPPS DIETER AMMERMANN 《The Journal of eukaryotic microbiology》1976,23(3):427-430
SYNOPSIS. Interaction of several plant lectins with the ciliates Stylonychia mytilus, Euplotes aediculatus, and Tetrahymena pyriformis GL, was investigated. The motility of Stylonychia is specifically inhibited by treatment with concanavalin A, with which the 2 other ciliates react only weakly. Stylonychia can regain its motility by shedding the lectin-loaded surface components and rebuilding a new pellicle. Other lectins used in this study did not interact with these ciliates. 相似文献
330.