Search results for "Concanavalin A"

Molecular structure of the cell wall receptor for killer toxin KT28 in Saccharomyces cerevisiae

1988

The adsorption of the yeast killer toxin KT28 to susceptible cells of Saccharomyces cerevisiae was prevented by concanavalin A, which blocks the mannoprotein receptor. Certain mannoprotein mutants of S. cerevisiae that lack definite structures in the mannan of their cell walls were found to be resistant to KT28, whereas the wild-type yeast from which the mutants were derived was susceptible. Isolated mannoprotein from a resistant mutant was unable to adsorb killer toxin. By comparing the resistances of different mannoprotein mutants, information about the molecular structure of the receptor was obtained. At least two mannose residues have to be present in the side chains of the outer chain …

Carbohydrate-Mediated Biomolecular Recognition and Gating of Synthetic Ion Channels

2013

Nanochannel-based biosensing devices have been proposed for selective detection of protein analyte molecules. However, the design and miniaturization of reusable channel-based biosensors is still a challenge in nanoscience and biotechnology. We present here a reusable nanofluidic biosensor based on reversible lectin-carbohydrate interactions. The nanochannels are fabricated in heavy ion tracked polymer membranes. The channel walls are functionalized with p-aminophenyl alpha-D-mannopyranoside (APMP) monolayers through carbodiimide coupling chemistry. The chemical (mannopyranoside) groups on the inner channel walls serve as binding sites and interact with specific protein molecules. The bindi…

Analysis of the polypeptide composition of the cell walls of Neurospora crassa. Similarities with the proteinaceous material secreted by the slime va…

1991

The polypeptide composition of cell walls from the wild-type strain of Neurospora crassa is compared with that of the proteinaceous extracellular coat (PEM) secreted by the slime strain of this fungus. Analyses included determination of the polypeptide pattern by polyacrylamide gel electrophoresis and blotting followed by staining with Concanavalin A and antibodies raised against the overall antigenic components present in either (whole cell walls or PEM) structure. A complex protein assortment was found associated to the walls of the wild type strain. The similarities observed between the polypeptide patterns of the cell walls and PEM, in addition to the immunological cross-reactivity exhi…

Inhibition of B2 receptor internalization delays its dephosphorylation

1997

Induction of apoptosis in a leukemia cell line by triterpene saponins from Albizia adianthifolia

2004

Abstract Triterpenoid saponins, which are present in plants and some marine animals, exert various important pharmacological effects. The present study examines the effects of adianthifoliosides A, B, and D (AdA, AdB, and AdD) together with two prosapogenins (Pro1 and Pro2) obtained from Albizia adianthifolia (Mimosaceae) on human leukemia T-cells (Jurkat cells) and on splenocytes. AdA, AdB, and AdD were found to exhibit a cytotoxic effect on Jurkat cells, whereas the prosapogenins were found to exert a lymphoproliferative effect on this cell type. Furthermore, all tested compounds were found to exert a synergistic lymphoproliferative activity with concanavalin A (ConA) on splenocytes. The …

Cutting Edge: A Key Pathogenic Role of IL-27 in T Cell- Mediated Hepatitis

2007

Abstract The signals driving T cell activation in T cell-mediated fulminant hepatitis are not fully understood. In this study, we identify the cytokine IL-27p28/EBI3 as a major pathogenic factor in the ConA model of T cell-mediated hepatitis. We found an up-regulation of hepatic EBI3 and p28 expression and augmented levels of IL-27 in wild-type mice after ConA administration, suggesting a potential pathogenic role of this cytokine in ConA hepatitis. Consistently, IL-27 EBI3-deficient mice were almost completely protected from ConA-induced liver damage. Such protection was associated with reduced levels of IFN-γ and its signaling proteins pSTAT-1 and T-bet. Finally, in vivo blockade of IL-27…

THz spectroscopy study of amyloid fibrils

2013

In suitable conditions proteins can modify their native conformation and associate to form aggregates with different morphologies in dependence on the external physico-chemical conditions. This phenomenon, one of the most challenging in life sciences, is associated with widely diffused pathologies such as Alzheimer’s, Parkinson’s and Creutzfeldt-Jacob’s diseases. Of particular relevance are ordered elongated aggregates with highly organized patterns of hydrogen-bonds, known as amyloid fibrils. While much biological and structural information are available about amyloids, and in spite of the fundamental paradigm of structure-dynamics-function relation in proteins, much less is known about th…

Fluctuation Methods To Study Protein Aggregation in Live Cells: Concanavalin A Oligomers Formation

2011

Prefibrillar oligomers of proteins are suspected to be the primary pathogenic agents in several neurodegenerative diseases. A key approach for elucidating the pathogenic mechanisms is to probe the existence of oligomers directly in living cells. In this work, we were able to monitor the process of aggregation of Concanavalin A in live cells. We used number and brightness analysis, two-color cross number and brightness analysis, and Raster image correlation spectroscopy to obtain the number of molecules, aggregation state, and diffusion coefficient as a function of time and cell location. We observed that binding of Concanavalin A to the membrane and the formation of small aggregates paralle…

Effects of hydrazyl group containing drugs on leucocyte functions: an immunoregulatory model for the hydralazine-induced lupus-like syndrome.

1985

Isoniazid (INH) and hydralazine (HYD) are transglutaminase (TGase, E.C.2.3.2.13.) substrates containing catalytically recruitable hydrazyl groups. Since they can be expected to inhibit TGase-mediated cell functions by competing with physiological substrates, their effect upon allogeneically and lectin-induced proliferation of mononucleocytes and upon zymosan-induced chemiluminescence of phagocytes was studied. Both compounds inhibited chemiluminescence in a dose-dependent manner. ID50 of HYD was consistently below 20 microM, while that of INH was above 120 microM. Proliferation of immunocompetent cells was suppressed by HYD with an ID50 of 60 microM, INH was inhibitory only above 5000 micro…

Regeneration of the cell wall in protoplasts of Candida albicans. A cytochemical study using wheat germ agglutinin and concanavalin A.

1988

To assess the dynamics of synthesis of the wall by regenerating Candida albicans protoplasts deposition of chitin and mannoproteins were investigated ultrastructurally using wheat germ agglutinin conjugated with either horseradish peroxidase or colloidal gold, and Concanavalin A coupled to ferritin respectively. Freshly prepared protoplasts lacked wheat germ agglutinin receptor sites but after 1-2 h of regeneration, they were detected. After 4-5 h of regeneration, the cell wall showed a discrete structure which was only labelled with wheat germ agglutinin in thin sections. At this stage of regeneration the outermost layer of the wall was labelled with clusters of Concanavalin A-ferritin par…