scholarly journals The effect of concanavalin A on the rat electro-olfactogram at various odorant concentrations

1987 ◽  
Vol 245 (1) ◽  
pp. 185-189 ◽  
Author(s):  
S G Shirley ◽  
E H Polak ◽  
D A Edwards ◽  
M A Wood ◽  
G H Dodd
Keyword(s):  
Concentration Dependence ◽  
Concanavalin A ◽  
Olfactory Receptor ◽  
Dissociation Constants ◽  
Con A ◽  
Odour Concentration ◽  
High Concentrations

We have studied the effect of concanavalin A (Con A) on the rat electro-olfactogram response to several odorants. Each odorant was applied over a range of concentrations. For hydrophobic odorants whose response was affected by Con A, the diminution in response was maximal at odorant concentrations of about 1 microM in the olfactory mucus. The (odour) concentration-dependence of the change is compatible with the idea that Con A inactivates one or more types of olfactory receptor that normally bind odorants with dissociation constants of the order of 100 nM. With hydrophilic odorants we had to apply concentrations very much higher than this to elicit any response from the system. At these high concentrations we could observe Con A-induced diminutions in response.

Evidence for a relationship between chloroquine and complement from studies with lymphocyte mitogens: possible implications for the mechanism of action of chloroquine in disease

1975 ◽  
Vol 21 (10) ◽  
pp. 1581-1586 ◽  
Author(s):  
D. R. Forsdyke
Keyword(s):  
Autoimmune Disease ◽  
Mechanism Of Action ◽  
Concanavalin A ◽  
Time Course ◽  
Con A ◽  
Therapeutic Value ◽  
Dependent Inhibition ◽  
High Concentrations

Chloroquine increases the inhibition of cultured lymphocytes by high concentrations of phytohemagglutinin (PHA) or concanavalin A (Con A). The inhibition is also increased by complement. Thus chloroquine and complement have similar effects. Time-course studies show that chloroquine increases the rate of onset of the complement-dependent inhibition. In serum preheated to inactivate complement, chloroquine can partially simulate the effect of complement. It is suggested that at certain stages in malaria or autoimmune disease the rate of clearance of parasitized erythrocytes or autoreactive lymphocytes is limited by the concentration of complement. Under these conditions a drug such as chloroquine, which could enhance or simulate the action of complement, might be of therapeutic value.

Cetyltrimethylammonium bromide (CTAB) promote amyloid fibril formation in carbohydrate binding protein (concanavalin A) at physiological pH

RSC Advances ◽  
2016 ◽  
Vol 6 (44) ◽  
pp. 38100-38111 ◽  
Author(s):  
Javed Masood Khan ◽  
Mohd Shahnawaz Khan ◽  
Mohd Sajid Ali ◽  
Nasser Abdulatif Al-Shabib ◽  
Rizwan Hasan Khan
Keyword(s):  
Concanavalin A ◽  
Cetyltrimethylammonium Bromide ◽  
Amyloid Fibril ◽  
Alpha Helix ◽  
Fibril Formation ◽  
Carbohydrate Binding ◽  
Con A ◽  
Amyloid Fibril Formation ◽  
High Concentrations ◽  
Β Sheet

Low concentration of CTAB provoked cross β-sheet formation whereas high concentrations of CTAB direct to alpha helix induction in Con A.

Role of concanavalin A as an endocytic modulator in Chinese hamster ovary cells

1981 ◽  
Vol 50 (1) ◽  
pp. 135-147
Author(s):  
B. Storrie ◽  
K.M. Maurey
Keyword(s):  
Concanavalin A ◽  
Chinese Hamster Ovary ◽  
Cho Cells ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
Con A ◽  
Ovary Cells ◽  
Fibroblast Line ◽  
High Concentrations ◽  
Secondary Lysosomes

The effect of the lectin, concanavalin A (Con A), on pinocytic uptake and pinosome-lysosome fusion in Chinese hamster ovary (CHO) cells, a fibroblast line, was investigated. The glycosylated protein, horseradish peroxidase (HRPase), and the non-glycosylated protein, 125I-labelled bovine serum albumin ([125I]BSA), was used as endocytic tracers. Con A at high concentrations (greater than or equal to 50 micrograms/ml) promoted the uptake of HRPase and inhibited the degradation of ingested HRPase. Con A inhibited the degradation of HRPase whether the two were added simultaneously or at different times to the cultures. Fusion of HRPase-positive pinosomes with secondary lysosomes was observed by electron microscopy in Con A-treated CHO cells. Con A at 200 micrograms/ml had no effect on either the uptake or degradation of [125I]BSA. Together these observations strongly suggest that the effects of high Con A concentrations on the uptake and degradation of HRPase are a consequence of direct complex formation between lectin and glycoprotein. Con A does not appear to have a general modulating effect on the dynamics of endocytic membrane in CHO cells.

Concanavalin A-induced Aggregation of Human Blood Platelets

1975 ◽  
Vol 33 (02) ◽  
pp. 354-360 ◽  
Author(s):  
Heinrich Patscheke ◽  
Reinhard Brossmer
Keyword(s):  
Concanavalin A ◽  
Binding Capacity ◽  
Specific Binding ◽  
Blood Platelets ◽  
Residual Effect ◽  
Independent Effect ◽  
Con A ◽  
Experimental Conditions ◽  
Main Effect ◽  
Induced Aggregation

SummaryConcanavalin A (CON A) causes platelets to aggregate. A Ca++-independent effect of CON A could be separated from a main effect which depends on Ca++. The main effect probably is a consequence of the CON A-induced platelet release reaction and therefore is platelet-specific. The weak residual effect observed in the presence of Na2EDTA may be due to a similar mechanism as has been demonstrated for CON A-induced aggregations of several other normal and malignant transformed animal cells.Na2EDTA did not inhibit the carbohydrate-specific binding capacity of CON A. Therefore, Na2EDTA appears not to demineralize the CON A molecules under these experimental conditions.α-methyl-D-glucoside inhibits the Ca++-independent as well as the Ca++-dependent effect of CON A.Pretreatment by neuraminidase stimulated the platelet aggregation induced by CON A. It is possible that removal of terminal sialic acid residues makes additional receptors accessible for the binding of CON A.

High concentrations of oxygen modulate in vitro Con A responses of rat lymphoid cells. Effect of 2-mercaptoethanol

1985 ◽  
Vol 11 (1) ◽  
pp. 51-55 ◽  
Author(s):  
Laurence Kraus ◽  
Philippe Lacombe ◽  
Michel Fay ◽  
Jean-Jacques Pocidalo
Keyword(s):  
Lymphoid Cells ◽  
Con A ◽  
High Concentrations

scholarly journals Visualization of intracellular concanavalin A binding sites in retinal photoreceptors.

1978 ◽  
Vol 26 (10) ◽  
pp. 822-828 ◽  
Author(s):  
I Nir
Keyword(s):  
Concanavalin A ◽  
Binding Sites ◽  
Photoreceptor Cells ◽  
Con A ◽  
Thin Sections ◽  
Glycol Methacrylate ◽  
Outer Segments ◽  
Retinal Photoreceptors ◽  
Carbohydrate Components ◽  
The Relationship

Localization of carbohydrate components in retinal photoreceptor cells and membranes was studied. Frog and rat retinas were fixed with glutaraldehyde and embedded in glycol methacrylate or in a mixture of glycol methacrylate, glutaraldehyde and urea. Thin sections were incubated with ferritin-labeled concanavalin A (F-Con A) and stained with osmium vapors. Intensive binding was observed in both rod and cone outer segments. In the rod inner segment, differential binding of F-Con A was demonstrated. While numerous ferritin granules were observed in the myoid zone, only a few were seen in the ellipsoid zone, except for a local accumulation along the plasma membrane. In the rod outer segment, Con A binding sites were closely associated with the disk membranes. Ferritin granules were observed on both sides of the membranes. The relationship between the localization of Con A binding sites and the orientation of visual pigment molecules within the rod outer segments disk membranes was discussed.

Factors Influencing the Reaction of α1-Fetoprotein with Concanavalin A and Lens Culinaris Agglutinin in Crossed Affinoimmunoelectrophoresis

1992 ◽  
Vol 38 (8) ◽  
pp. 1418-1424 ◽  
Author(s):  
D Magne ◽  
N Seta ◽  
D Lebrun ◽  
G Durand ◽  
D Durand
Keyword(s):  
Concanavalin A ◽  
Lens Culinaris ◽  
Biological Fluids ◽  
Con A ◽  
Cellular Origin ◽  
Lens Culinaris Agglutinin ◽  
Lentil Lectin ◽  
Wide Range ◽  
Minimal Quantity ◽  
Antibody Ratio

Abstract Concanavalin A (Con A) and lentil lectin (LCA) analysis of alpha-fetoprotein (AFP) glycosylation heterogeneity is used in a variety of clinical situations. We studied the influence of analytical conditions on the separation of AFP glycoforms by using lectin-crossed affinoimmunoelectrophoresis, regardless of the AFP concentration, which can vary over a wide range in biological fluids. We defined the optimal concentration of Con A (2 g/L) and LCA (0.35 g/L) in the first-dimension gel, together with the optimum antigen (AFP)/antibody ratio in the second-dimension gel. The presence of protein in the diluent used for AFP samples was found to change the shape of crossed affinoimmunoelectrophoresis patterns without changing the percentage composition of AFP fractions. The within-run CV was less than 4% for both lectins, and the between-run CV was less than 6.3%. The minimal quantity of AFP that provided a visible pattern with both lectins was 4 ng, corresponding to 50 microL of an 80 micrograms/L AFP sample. These technical conditions allow the cellular origin of AFP to be determined, regardless of the concentration in the sample. Typical AFP lectin patterns of secreting tumors are compared with fetal and cord serum AFP.

scholarly journals Identification of high-affinity (Kd 0.35 mumol/L) and low-affinity (Kd 7.9 mumol/L) platelet binding sites for ADP and competition by ADP analogues

Blood ◽  
1988 ◽  
Vol 71 (1) ◽  
pp. 110-116 ◽  
Author(s):  
JR Jefferson ◽  
JT Harmon ◽  
GA Jamieson
Keyword(s):  
Platelet Activation ◽  
Dissociation Constants ◽  
Partial Agonist ◽  
Adenine Nucleotides ◽  
Blood Platelets ◽  
Ionophore A23187 ◽  
High Affinity ◽  
Binding Isotherms ◽  
High Affinity Site ◽  
High Concentrations

Steady-state binding of ADP to blood platelets and isolated membranes has not previously been obtained because of complications arising from metabolism of the ligand and dilution due to its secretion from storage granules. In the present studies, competition binding isotherms (n = 9) using paraformaldehyde-fixed platelets showed that [2–3 H]ADP bound to two sites with a small amount (approximately 5% of total) of nonspecific binding: 410,000 +/- 40,000 sites of low affinity (Kd 7.9 +/- 2.0 mumol/L) and 160,000 +/- 20,000 sites of high affinity (Kd 0.35 +/- 0.04 mumol/L) corresponding to the ADP concentration required for activation in fresh platelets (0.1–0.5 mumol/L). All agonists and antagonists examined were able to compete with ADP at the high-affinity site. The strong platelet agonists 2-methylthio ADP and 2-(3- aminopropylthio)ADP competed with ADP at the high-affinity site with dissociation constant values of 7 mumol/L and 200 mumol/L, respectively. The partial agonist 2′,3′-dialdehyde ADP and the weak agonist GDP also competed at the high-affinity site with Kd values of 5 mumol/L and 49 mumol/L, respectively. The sequence of binding affinities of other adenine nucleotides at the high-affinity site corresponded to their relative activities as known antagonists of platelet activation by ADP; namely, ADP(Kd 0.35 mumol/L) approximately equal to ATP (Kd 0.45 mumol/L) much greater than AMP (Kd 360 mumol/L). Adenosine and 2-chloroadenosine did not compete with ADP. ADP binding to the high-affinity site was inhibited by p-mercuribenzene sulfonate (Ki 250 mumol/L) but only very weakly by 5′-p- fluorosulfonylbenzoyladenosine (Ki 1 mmol/L). All the above nucleotides also competed with ADP at the low-affinity sites but, because of the high concentrations of competing nucleotide required, dissociation constants at this site were obtained only for ATP (21 mumol/L), 2-MeS ADP (200 mumol/L) and 2′,3′-dialdehyde ADP (270 mumol/L). 8-Bromo ADP competed strongly with ADP at the high-affinity site (Kd 0.40 mumol/L) but weakly if at all at the low-affinity site. 8-Bromo ADP inhibited platelet activation induced by ADP (EC50 approximately 100 mumol/L) but not by collagen, thrombin, or ionophore A23187.(ABSTRACT TRUNCATED AT 400 WORDS).

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