Hyaluronic acid (HA) is an anionic biopolymer that is present in many tissues and can be involved in cancerous neoformations. HA can form complexes with proteins (particularly, serum albumin) in the body. However, HA structures and processes involving HA have not been extensively studied by NMR because the molecule's rigid structure makes these studies problematic. In the current work, self-diffusion of HA and bovine serum albumin (BSA), and water in solutions was measured by (1)H pulsed field gradient NMR (PFG NMR) with a focus on the HA-BSA-D2O systems at various concentrations of BSA and HA. It was shown that in the presence of even a small amount of HA, the self-diffusion coefficient (SDC) of BSA decreases. To explain this fact, three hypotheses were proposed and analyzed. The first one was based on the effect of slowing down of water mobility in the presence of HA. The second hypothesis suggested an effect of mechanical collisions of BSA with HA molecules. The third hypothesized that BSA and HA molecules form a complex where BSA molecules reduced in mobility. It was shown that the third mechanism is the most likely. The state of the BSA molecules in the BSA-HA-D2O system corresponds to a 'fast exchange' condition from the NMR point of view: BSA molecules reside in the 'free' and 'bound' (with HA) states for much shorter time than the diffusion time of the PFG NMR experiment, 7 ms. The fractions of 'bound' BSA molecules in the BSA-HA complex were estimated.

No abstract

No abstract

No abstract

Water self-diffusion was studied in model biological membranes (lipid bilayers of dioleoylphosphatidylcholine (DOPC) and dimyristoylphosphatidylcholine) by nuclear magnetie resonance with pulsed field gradient. The results for DOPC-water bilayers for three different orientations of the angle 0 between the direction of the field gradient and the normal to the bilayer (0 = 57.4, 90, 0 o) were presented. The differences in the diffusion deeay shapes and values of the diffusion coefficients, obtained at different bilayer o¡ and demonstrating highly anisotropic diffusion of the interbilayer water was discussed. This study also has shown some features of water diffusion in model lipid bilayers at the concentrations corresponding to the presence of bound and quasi-free water. The dependence of the water and lipid diffusion on the water content was considered from the point of view of the bilayers hydration and types of interbilayer water.