Lectin Of The Rock, Chemical Modification And Spectral Analysis; Wind And Rain To Spend The Mannose Binding Lectin Gene Of Bioinformatics Analysis And Its Expression In E. Coli And Purified

The effects of modifications of the carbohydrate chain and amino acids on the conformation and activity of Millettia Dielsiana harms lectin(MDL) were studied by hemagglutination analysis, fluorescence and circular dichroism. The modification of tryptophan residues led to a compete loss of hemagglutinating activity, while mannose could prevent the loss of the activity. The results indicated that 2 tryptophan residues were involved in the carbohydrate-binding site. Modifications of carboxyl groups residues resluted in 80% loss of the activity, but the presence of mannose could protect against the modification. The results suggested that carboxyl groups of aspartic and glutamic acids were involved in the carbohydrate binding site of the lectin. However, the oxidation of carbohydrate chain and modification of histidine, arginine residues did not affect the hemagglutinating activity of MDL. Fluorescence studies of MDL indicated that tryptophan residues were present in a relative hydrophobic region, and binding of mannose to MDL could quench tryptophan fluorescence without any change of λmax. CD spectrum showed that all of these modifications affected the conformation of MDL molecule at different extents except the modification of arginine residues Fluorescence quenching showed that acrylamide and iodoacetic acid could quench 77% and 98% of the fluorescence of tryptophan in MDL, respectively. However, KIalmost didn't quench the fluorescence of MDL even when the concentration of I-was 0.15mol/L. It showed that most of tryptophan residues located in relatively hydrophobic or negatively charged areas near to MDL surface.