title: Spectroscopic studies on the protective effect of a specific sugar on concanavalin A at acidic, neutral and alkaline pH.
abstract: A Systematic investigation of the effect of pH on concanavalin A in the presence of specific and non-specific sugars is made using CD (circular dichroism) and fluorescence. The specific and non-specific sugars for concanavalin A were methyl alpha-D-glucopyranoside and methyl alpha-D-galactopyranoside respectively. Far-UV CD showed changes in the MRE value at 217 nm in the presence of the above-mentioned sugars. At pH 7, the CD and fluorescence spectra obtained in the presence of methyl alpha-D-glucopyranoside were slightly different from those for the native state and a significant difference was obtained in the presence of methyl alpha-D-galactopyranoside. Near-UV CD spectra showed the retention of a native-like tertiary structure in the presence of the specific sugar upon pH denaturation. Tryptophan fluorescence studies indicated a change in the tryptophan enviornment. The results obtained from our CD data are consistent with those obtained from fluorescence studies. Upon pH exposure of concanavalin A in the presence of methyl alpha-D-glucopyranoside and methyl alpha-D-galactopyranoside, the former acted as a protector preventing conformational alteration at different pH while the presence of latter induced a different stable conformational state and this state persists over the pH range from 2 to 10.
authors.affiliation: Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh-202002, India. rizwanhkhan@hotmail.com
authors.forename: Rizwan Hasan
authors.initials: RH
authors.lastname: Khan
authors.forename: Aabgeena
authors.initials: A
authors.lastname: Naeem
authors.forename: Masroor Alam
authors.initials: MA
authors.lastname: Baig
mesh_terms: D002942:Circular Dichroism; D003208:Concanavalin A / Q000737:chemistry / Q000378:metabolism*; D005690:Galactose / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008757:Methylglucosides / Q000737:chemistry / Q000378:metabolism*; D013050:Spectrometry, Fluorescence
chemical_list: D008757:Methylglucosides; C469243:methyl-galactopyranoside; D003208:Concanavalin A; C027020:methylglucoside; D005690:Galactose