INTERACTIONS OF HYALURONAN (HYALURONIC-ACID) WITH PHOSPHOLIPIDS AS DETERMINED BY GEL-PERMEATION CHROMATOGRAPHY, MULTI-ANGLE LASER-LIGHT-SCATTERING PHOTOMETRY AND H-1-NMR SPECTROSCOPY

The chain flexibility of solutions of hyaluronan (HA) of different mol ecular weights was determined by H-1-NMR spectroscopy in the absence a nd presence of the phospholipid dipalmitoyl-D,L-alpha-phosphatidylchol ine (DPC). Sonication of high- or low-molecular-weight HA with DPC for periods of up to 120 min markedly increased HA chain flexibility as d etermined by observing the half-peak linewidths (Delta v(1/2)) for the methyl protons of the acetamidodeoxyglucose residues of the HA molecu les. Gel permeation chromatography of mixtures of purified high-molecu lar-weight HA (Healon(R)) with H-3-DPC or H-3-platelet activating fact or (PAF) showed exclusion of these radioactively labelled molecules fr om the gel in the presence of HA but not in its absence. Studies using multi-angle laser-light-scattering (MALLS) photometry of sonicates of DPC and Healon(R) after Superose 6 chromatography revealed increases in HA (M) over bar(w), (M) over bar(n), (M) over bar(z),and their corr esponding root mean square radii relative to control sonicates of HA w ithout DPC. From these data, we have deduced that DPC binds to HA by c ompeting for those hydrophobic centres along the HA chain which are no rmally responsible for the inter- and intra-chain interactions and whi ch confer stiffness to the HA molecule. It is proposed that such inter actions in arthritic joints could reduce synovial fluid viscoelasticit y thereby diminishing the ability of this medium to protect articular cartilage from mechanical injury.