Polymerization Sites in the D-Domain of Human Fibrin(ogen)

E. V. Lugovskoy, E. N. Zolotareva, G. K. Gogolinskaya, P. G. Gritsenko, E. D. Moroz, and S. V. Komisarenko^*

Palladin Institute of Biochemistry, Ukrainian Academy of Sciences, ul. Leontovicha 9, Kiev, 01601 Ukraine; fax: (380-44) 229-6365; E-mail: svk@biochem.kiev.ua

^* To whom correspondence should be addressed.

Received November 30, 2000; Revision received June 26, 2001

---

The present work deals with localization of previously unknown polymerization sites of the fibrin DD-fragment. D-dimer we obtained has a pronounced inhibitory effect on fibrin polymerization (IC₅₀ = 0.06 µM). The inhibitory effect of the DD-fragment disappeared after reduction and carboxymethylation. However, polypeptide chains beta_DD (Bbeta134-461) and gammagamma_DD (gamma63-411)₂ of the DD-fragment, isolated by preparative electrophoresis, displayed their inhibitory activity. For instance, the rates of fibrin protofibril lateral association were decreased twice in the presence of beta_DD and gammagamma_DD chains at their molar ratios to fibrin of 0.40 and 0.15, respectively. The IC₅₀ values for beta_DD and gammagamma_DD were 0.24 and 0.10 µM, respectively. Highly specific inhibition of protofibril lateral association suggests that the protofibril lateral association sites are located in Bbeta134-461 and gamma63-411 regions of the fibrin D-domain. Our data confirm those reported by Doolittle et al. regarding the gamma-chain and a hypothesis about beta-chain of fibrin D-domain (Yang, Z., Mochalkin, I., and Doolittle, R. F. (2000) Biochemistry, 97, 14156-14161).

---

KEY WORDS: fibrin(ogen), D-domain, polymerization sites

---