Biomaterial Database

Binding of 4-methylumbelliferyl beta-D-galactopyranoside to Momordica charantia lectin: fluorescence-quenching studies. 1981

M I Khan, and T Mazumder, and D Pain, and N Gaur, and A Surolia

The binding of 4-methylumbelliferyl beta-D-galactopyranoside (MeUmb-Galp), to Mormordica charantia lectin was studied by equilibrium dialysis and quenching of ligand fluorescence. The fluorescence of MeUmb-Galp decreases as a function of solvent polarity. On binding to M. charantia lectin, its fluorescence was nearly 100% quenched, showing that the binding of the glycoside takes place in hydrophobic environment. The binding of the fluorescent sugar was saccharide-specific as evidenced by reversal of MeUmb-Galp fluorescence quenching by lactose. The association constant is independent of the experimental method used and at 25 degrees C the value is (1.96 +/- 0.05) X 10(4) M-1. The number of binding sites as determined by equilibrium dialysis and fluorescence quenching agree very well with each other; n being equal to 1.98 +/- 0.02. The Ka value for the glycoside was also determined by competition studies employing reversal of fluorescence quenching of MeUmb-Galp by lactose. The value of ka obtained for lactose is 1.21 X 10(4) M-1 at 30 degrees C. The internal consistency of the association constant and number of binding site values at low and high saturation indicates the absence of additional subsite on M. charantia lectin. The thermodynamic parameters do not differ greatly with change in temperature; the values of - delta H degrees and - delta S degrees are equal to 30 +/- 9.63 kJ mol-1 and 21 +/- 0.3 J mol-1 K-1 respectively in the range of 15--35 degrees C indicting that the binding of M. charantia lectin to saccharide is exothermic in nature.

UI	MeSH Term	Description	Entries
D010944	Plants	Multicellular, eukaryotic life forms of kingdom Plantae. Plants acquired chloroplasts by direct endosymbiosis of CYANOBACTERIA. They are characterized by a mainly photosynthetic mode of nutrition; essentially unlimited growth at localized regions of cell divisions (MERISTEMS); cellulose within cells providing rigidity; the absence of organs of locomotion; absence of nervous and sensory systems; and an alternation of haploid and diploid generations. It is a non-taxonomical term most often referring to LAND PLANTS. In broad sense it includes RHODOPHYTA and GLAUCOPHYTA along with VIRIDIPLANTAE.	Plant
D005697	Galactosides	Glycosides formed by the reaction of the hydroxyl group on the anomeric carbon atom of galactose with an alcohol to form an acetal. They include both alpha- and beta-galactosides.
D006027	Glycosides	Any compound that contains a constituent sugar, in which the hydroxyl group attached to the first carbon is substituted by an alcoholic, phenolic, or other group. They are named specifically for the sugar contained, such as glucoside (glucose), pentoside (pentose), fructoside (fructose), etc. Upon hydrolysis, a sugar and nonsugar component (aglycone) are formed. (From Dorland, 28th ed; From Miall's Dictionary of Chemistry, 5th ed)	Glycoside
D006923	Hymecromone	A coumarin derivative possessing properties as a spasmolytic, choleretic and light-protective agent. It is also used in ANALYTICAL CHEMISTRY TECHNIQUES for the determination of NITRIC ACID.	Imecromone,Methylumbelliferone,Resocyanine,4-Methylumbelliferone,7-Hydroxy-4-methyl-coumarin,Cholestil,Mendiaxon,4 Methylumbelliferone,7 Hydroxy 4 methyl coumarin
D001665	Binding Sites	The parts of a macromolecule that directly participate in its specific combination with another molecule.	Combining Site,Binding Site,Combining Sites,Site, Binding,Site, Combining,Sites, Binding,Sites, Combining
D013050	Spectrometry, Fluorescence	Measurement of the intensity and quality of fluorescence.	Fluorescence Spectrophotometry,Fluorescence Spectroscopy,Spectrofluorometry,Fluorescence Spectrometry,Spectrophotometry, Fluorescence,Spectroscopy, Fluorescence
D014468	Umbelliferones	7-Hydroxycoumarins. Substances present in many plants, especially umbelliferae. Umbelliferones are used in sunscreen preparations and may be mutagenic. Their derivatives are used in liver therapy, as reagents, plant growth factors, sunscreens, insecticides, parasiticides, choleretics, spasmolytics, etc.	7-Hydroxycoumarins,Hydrangin,Skimmetin,7 Hydroxycoumarins
D037102	Lectins	Proteins that share the common characteristic of binding to carbohydrates. Some ANTIBODIES and carbohydrate-metabolizing proteins (ENZYMES) also bind to carbohydrates, however they are not considered lectins. PLANT LECTINS are carbohydrate-binding proteins that have been primarily identified by their hemagglutinating activity (HEMAGGLUTININS). However, a variety of lectins occur in animal species where they serve diverse array of functions through specific carbohydrate recognition.	Animal Lectin,Animal Lectins,Isolectins,Lectin,Isolectin,Lectin, Animal,Lectins, Animal
D037121	Plant Lectins	Protein or glycoprotein substances of plant origin that bind to sugar moieties in cell walls or membranes. Some carbohydrate-metabolizing proteins (ENZYMES) from PLANTS also bind to carbohydrates, however they are not considered lectins. Many plant lectins change the physiology of the membrane of BLOOD CELLS to cause agglutination, mitosis, or other biochemical changes. They may play a role in plant defense mechanisms.	Lectins, Plant,Phytagglutinin,Plant Agglutinin,Plant Lectin,Agglutinins, Plant,Phytagglutinins,Plant Agglutinins,Agglutinin, Plant,Lectin, Plant