SYNTHETIC PEPTIDES DERIVED FROM MIDKINE ENHANCE PLASMINOGEN-ACTIVATORACTIVITY IN BOVINE AORTIC ENDOTHELIAL-CELLS

Chemically synthesized human midkine enhanced plasminogen activator ac tivity and decreased its inhibitor levels in bovine aortric endothelia l cells. These activities were preserved in the C-terminal half, but n ot in the N-terminal half of the midkine molecule. Furthermore, a synt hetic peptide of 43 amino acids designated as ''C-domain'', which form ed the compact structure held by two disulfide bonds in the C-terminal half, mimicked intact midkine. Chemically synthesized C-domain of ple iotrophin (43 amino acids), which was 53% identical to midkine C-domai n in amino acid sequence, expressed the similar activities. These 43 a mino acid peptides are, so far, the shortest peptide able to enhance t he fibrinolytic activities of the endothelial cells. (C) 1995 Academic Press, Inc.