Study of the interactions of D- and L-polylysine enantiomers withpectate in aqueous solutions.
The interaction between D- and L-enantiomers of polylysine and potassium pectate was studied by means of CD, microcalorimetry, and osmometry. Upon binding with pectate, only poly(L-lysine) undergoes a coil to alpha-helix transition, while poly(D-lysine) remains in the disordered state. This suggest that the energetics of the interaction is influenced by stereochemical constraints besides electrostatic forces. Experimental findings from microcalorimetry suggest that a contribution to the overall enthalpy of binding comes from the polysaccharidic moiety. Stoichiometry of the macromolecular complexes studied by osmometry gives a polylysine:pectate ratio of 3:1, in agreement with the respective degree of polymerization of the two polyelectrolytes.
Paradossi
G
G
Department of Chemistry, University of Rome, Tor Vergata, Italy. paradossi@uniromaz.it
Chiessi
E
E
Malovíková
A
A
D002151:Calorimetry; D002942:Circular Dichroism; D010368:Pectins / Q000737:chemistry*; D011107:Polylysine / Q000737:chemistry*; D017433:Protein Structure, Secondary; D012996:Solutions; D013237:Stereoisomerism; D014867:Water
D012996:Solutions; D014867:Water; D011107:Polylysine; D010368:Pectins; C003181:polygalacturonic acid