THE RELATION BETWEEN THE ADSORPTION BEHAVIOR AT THE INTERFACE AND THECONFORMATIONAL-CHANGES IN HYALURONATES PARTIALLY MODIFIED WITH VARIOUS ACYL CHAINS

Partially acylated hyaluronates, respectively having a different acyl chain and polysaccharide chain, were prepared as water-soluble derivat ives with substitution degrees of approximately 1/33. Conformational c hanges of polysaccharide chains with partial acylation were studied on the CD spectrum of the induced cotton effects of the derivatives-thia zine dye complexes. Significant cotton effects were observed in deriva tives having the combination of hyaluronate molecular weight from 70,0 00 to 2,000,000 and a lauroyl or palmitoyl chain as the acetyl group. HA37-P, particularly, which introduced palmitoyl chains for hyaluronat es of the molecular weight 370,000, exhibited typical cotton effects, and the kinetic viscosity of HA37-P solution lowered compared with tha t of unmodified HA37. These acyl derivatives exhibited significant con formational changes on the CD spectrum, and lowered the interfacial te nsion of n-octane to water. It was confirmed that HA37-P in particular lowers the interfacial tension by adsorbing oil droplets and contribu tes to improve the membrane fluidity by the fluorescent probe method. The formation of exiplexes under oil-free conditions suggested that th e partial acyl hyaluronates having a hydrophobic-hydrophilic combinati on such as HA37-P might form a micellar polymer in water by themselves .