| Abstract: | Optical mixing spectroscopy is a recently developed technique which permits the measurement of diffusion coefficients and molecular weights of macromolecular species when only small amounts of material can be obtained for analyses. In this study, an approxmate empirical relationship between diffusion coefficient and viscosity-average molecular weight was established for highly sulfated mucopolysaccharides. This relationship was then used to deduce the molecular weights of small quantities of highly purified dermatan sulfate extracted from human placenta at the full term (40 weeks) and at earlier stages of development (12–18 weeks). The effect of hyaluronidase digestion on molecular weight was then investigated as a probe for glucuronic acid substitutions in the dermatan sulfate. The molecular weights of dermatan sulfate were similar, 27,000–29,000, in the term and young placenta. Digestion with hyaluronidase produced a 50% reduction in molecular weight in the young placenta versus a 30% reduction in the term placenta, clearly demonstrating significant differences in the nature of glucuronic acid substitution at the two developmental stages studied. |
