Study of hyaluronic acid flexibility by electric birefringence

Abstract

Transient-electric-birefringence experiments were conducted on four samples of hyaluronic acid over the molecular-mass (M) range 5 x 10-4 x 106 in dilute aqueous solution. The geometrical, optical and electrical characteristics were monitored via the rotary relaxation times, optical-polarizability antisotropies and electrical polarizabilities respectively. Each indicates the molecular conformation to be consistent with some degree of rigidity at low M but that this does not persist at high M. The molecules do not become true random coils, but are best characterized in terms of a persistence length of 20nm or 20 disaccharide units.

Conformational contraction and hydrolysis of hyaluronate in sodium hydroxide solutions

“…The slope of Kc/I, P = d(KcH)/dq2, at high angles should thus be roughly constant as the depolymerization proceeds. In fact if a scaling law of the type Sin2(i/2) (S2) = aMv (15) exists, and 2Agc is independent of angle, it then follows from eq. 10 d (Kc/I(q)) = i ( 16) dq2 ¿ This is an interesting property of d(Kc/I)/dq2 and shows that P remains constant as M changes for ideal coils ( = 1).…”

“…analysis software were developed for a multiangle Wyatt Technology Dawn scattering photometer operating in the "batch mode", that is, with a 25 mm diameter scintillation vial instead of the HPLC flow cell. The ability to simultaneously monitor many (15) angles allows not only the average number of polymer links broken per original molecule per unit time to be determined but also the weight average molecular weight, Afw, and z-averaged mean square radius of gyration (S2}z.…”

Interactions of Hyaluronan Layers with Similarly Charged Surfaces: The Effect of Divalent Cations

“…Considering the bound-water effects and the 3 nm in-air and 100 nm in-water ellipsometric thickness of hydrated HA layer, we propose the structure of HA shown in Figure a where each polymer could be grafted to the surface in more than one location (“trains”) with “loops” in between the trains and free ends (“tails”). The radius of gyration R g of HA with molecular weight M HA = 10 6 is of the order of 200 ± 50 nm, , where each molecule covers an area A ≈ (2 R g ) 2 and the molecules are close-packed on the surface. The ellipsometrically measured thickness L HA = 100 nm, less than R g , is the “averaged” height of HA layer, which is used also for force measurement and calculation.…”

A water molecule participates in the secondary structure of hyaluronan

“…Although this complete structure has so far been proven to exist only in Me2SO, the first proposal for part ofit (containing hydrogen-bonded acetamido, carboxylate and hydroxy groups [7]) was based on work in aqueous solutions, involving kinetic studies of periodate oxidation of the glucuronate glycol groups [7]. The extended hydrogenbonded arrays, down both 'sides' of the HA, must, if present, result in considerable rigidity of the polymer, and it has long been known that HA behaves in aqueous solution as an unusually 'stiff' polymer [1,8]. This stiffness would be of advantage in its role as a spacefilling material [5].…”