Thermodynamics of monosaccharide binding to concanavalin A, pea (Pisum sativum) lectin, and lentil (Lens culinaris) lectin

• Published in: The Journal of biological chemistry Vol. 268; no. 11; pp. 7668 - 7677
• Main Authors: Schwarz, F.P, Puri, K.D, Bhat, R.G, Surolia, A
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Biochemistry and Molecular Biology 15.04.1993
• Subjects: Analytical, structural and metabolic biochemistry; Biological and medical sciences; CALORIMETRIA; CALORIMETRIE; Calorimetry; Calorimetry, Differential Scanning; Concanavalin A - chemistry; DENATURATION; DESNATURALIZACION; FISICA; Fundamental and applied biological sciences. Psychology; Glycoproteins; LECTINA; LECTINE; Lectins - chemistry; LENS CULINARIS; Ligands; MONOSACARIDOS; MONOSACCHARIDE; Monosaccharides - chemistry; PHYSIQUE; PISUM SATIVUM; Plant Lectins; Proteins; Structure-Activity Relationship; TEMPERATURA; TEMPERATURE; Thermodynamics; Differential scanning calorimetry; Ligand binding; Lectin; Oligosaccharide; Thermal denaturation; Glycoproteins; Thermodynamic analysis; Concanavalin A
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/s0021-9258(18)53009-x

Titration calorimetry measurements of the binding of methyl alpha-D-mannopyranoside (Me alpha Man), D-mannopyranoside (Man), methyl alpha-D-glucopyranoside (Me alpha Glu), and D-glucopyranoside (Glu) to concanavalin A (Con A), pea lectin, and lentil lectin were performed at 281 and 292 K in 0.01 M dimethylglutaric acid-NaOH buffer (pH 6.9) containing 0.15 M NaCl and Mn+2 and Ca+2 ions. The site binding enthalpies, delta H, are the same at both temperatures and range from -28.4 +/- 0.9 (Me alpha Man) to -16.6 +/- 0.5 kJ mol-1 (Glu) for Con A, from -26.2 +/- 1.1 (Me alpha Man) to -12.8 +/- 0.4 kJ mol-1 (Me alpha Glu) for pea lectin, and from -16.6 +/- 0.7 (Me alpha Man) to -8.0 +/- 0.2 kJ mol-1 (Me alpha Glu) for lentil lectin. The site binding constants range from 17 +/- 1 X 10(3) M-1 (Me alpha Man to Con A at 281.2 K) to 230 +/- 20 M-1 (Glu to lentil lectin at 292.6 K) and exhibit high specificity for Con A where they are in the Me alpha Man:Man:Me alpha Glu:Glu ratio of 21:4:5:1, while the corresponding ratio is 5:2:1.5:1 for pea lectin and 4:2:2:1 for lentil lectin. The higher specificity for Con A indicates more interactions between the amino acid residues at the binding site and the carbohydrate ligand than for the pea and lentil lectin-carbohydrate complexes. The carbohydrate-lectin binding results exhibit enthalpy-entropy compensation in that delta H(b) (kJ mol-1) = -1.67 +/- 0.06 X 10(4) + (1.30 +/- 0.12)T(K) delta S(b) (J mol-1 K-1). Differential scanning calorimetry measurements on the thermal denaturation of the lectins and their carbohydrate complexes show that the Con A tetramer dissociates into monomers, while the pea and lentil lectin dimers dissociate into two submonomer fragments. At the denaturation temperature, one carbohydrate binds to each monomer of Con A and the pea and lentil lectins. Complexation with the carbohydrate increases the denaturation temperature of the lectin and the magnitude of the increases yield binding constants