Synthetic peptides from C-reactive protein containing tuftsin-related sequences

Abstract

Peptides containing Lys-Pro-Arg or Thr-Lys-Arg segments corresponding to various regions of human C-reactive protein were synthesized. The peptides prepared were composed of amino acid residues, 37–58, 51–58, 173–187 and 181–187 of C-reactive protein. The relationship between C-reactive protein, its synthetic fragments and tuftsin (Thr-Lys-Pro-Arg) was investigated in binding studies, enhancement of phagocytosis and change in cyclic nucleotide levels of mouse macrophages. The peptides AA 51–58 and 181–187 did enhance macrophage phagocytosis capacity to a similar extent to that of tuftsin. They showed however only negligible binding to the cells. The effect of C-reactive protein and the synthetic peptides on metabolic activity of neutrophils was also investigated. It was shown that the peptides inhibited to some degree superoxide production, lysozyme release and Vitamin B 12 binding protein release from neutrophils in the absence and presence of the stimulants, PMA or Con A. Comparable activity with tuftsin was not found.