Polymerization Sties Of Desialated Fibrinogen
It has long been known (Laki and Chandrasekhar, Nature, 197:1267,1963) that the enzymatic removal of sialic acid (SA) frcm fibrinogen (F) shortens the thrccabin clotting time. Martinez et al. (J. Lab. Clin. Med., 89:367, 1977) demonstrated that this phenomenon is due to enhanced fibrin monomer polymerization. To more accurately identify the mechanisms involved we examined the binding of normal F, V. cholerae neuraminidase - treated F (NF) and their plasmic digests. Mean SA content of F of 4.5 residues / molecule decreased to unmeasurable levels in NF with a concomitant 10s shortening of the thrombin clotting time. F, NF, and plasmin digests of F (FP) and NF (NFP) were subjected to fibrin-monomer-Sepharose chromatography (FMSC) essentially according to Kudryk and Blcmback (J.Biol. Chan., 249:3322, 1974) and effluent fractions analyzed by SDS polyacrylamide gel electrophoresis (SDS-PAGE) under nonreducing conditions. Mean values for F retained on FMSC and eluted with acid urea buffer was 61%, for NF 86%, for for FP 65%, for NFP 78%. In NFP and FP 3 fragments D (D1, D2 D3) of Mr 103K, 89K, and 83K were discerned by SDS-PAGE. D1 in FP and NFP was almost quantitatively retained on FMSC, whereas little, if any, D3 was retained frcm either digest. FMSC resulted in poor retention of D2 for FP and virtually complete retention of this fragment from NFP. Fragments E were not retained on FMSC of either FP or NFP. The data suggests that desialation of F exposes additional polymerization sites present in D2 but not D3 of F.