Thermodynamic analysis of chitooligosaccharide binding to Urtica dioica agglutinin by isothermal titration calorimetry.
UDA (Urtica dioica agglutinin) contains two hevein like domains with two non-identical interacting sites and is specific for chitooligosaccharides. The binding of chitooligosaccharides to UDA was studied by Isothermal Titration Calorimetry. Each site is composed of three subsites, each binding to a sugar residue. Thermodynamic parameters obtained show that while chitobiose has two independent non-interacting sites, chitotriose, chitotetrose and chitopentose have two interacting sites on each monomer of UDA. Values of binding enthalpy (deltaH) increase almost by a factor of 7 in going from chitobiose to chitotriose indicating the existence of three subsites in the combining site of UDA. The binding constant for chitotetrose and chitopentose increase without any further enhancement in the values of deltaH indicating that for oligomers larger than chitotriose interaction is favoured entropically.
Katiyar
S
S
Molecular Biophysics Unit, Indian Institute of Science, Bangalore.
Van Damme
E J
EJ
Peumans
W J
WJ
Surolia
A
A
D023181:Antimicrobial Cationic Peptides; D001665:Binding Sites; D002151:Calorimetry; D002686:Chitin / Q000737:chemistry; D037102:Lectins / Q000737:chemistry*; D019684:Magnoliopsida / Q000737:chemistry*; D009844:Oligosaccharides / Q000737:chemistry*; D037121:Plant Lectins; D010940:Plant Proteins / Q000737:chemistry; D017434:Protein Structure, Tertiary; D013816:Thermodynamics
D023181:Antimicrobial Cationic Peptides; D037102:Lectins; D009844:Oligosaccharides; D037121:Plant Lectins; D010940:Plant Proteins; C045875:hevein; D002686:Chitin; C012238:chitotetrose