2 NON-PROLINE CIS PEPTIDE-BONDS MAY BE IMPORTANT FOR FACTOR-XIII FUNCTION

The structure of recombinant human cellular factor XIII zymogen was so lved in its monoclinic crystal form and refined to an R-factor of 18.3 % (R-free=23.6%) for all data between 40.0 and 2.1 Angstrom resolution . Two non-proline cis peptide bonds were detected, One is between Arg( 310) and Tyr(311) close to the active site cysteine residue (Cys(314)) and the other is between GIn(425) and Phe(426) at the dimerization in terface. The structure and the role of these cis peptides are discusse d in the light of their possible importance for factor XIII function. (C) 1998 Federation of European Biochemical Societies.