892 HUMAN PLASMA POLYAMINE-CONJUGATED PEPTIDE, PUTRESCINI

To define a cystic fibrosis factor and its potential relationship to polyamine metabolism an investigation of the low molecular weight peptide profile of human blood was undertaken. Previous investigations indicated polyamines were detectable in serum and plasma following extensive alkali or acid hydrolysis. We report the existance of a polyamine peptide conjugate in human plasma. This peptide was isolated by fractionation of citrated whole human plasma following chromatography on Biogel P10. The elution profile, monitored at 220nm, resulted in the identification of 6 peaks. These polypeptides had a molecular weight range of 2 to 10,000 daltons as evidence by retention on Diaflomembranes and gel chromatography. The major peak (putrescinin) was purified by Biogel P6 chromatography, paper chromatography and DEAE celulose chromatography. This plasma peak was present in CF patients and controls, and disappeared from blood following coagulation. The molecular weight of putrescinin was 4600 daltons. Amino acid analysis revealed 43 amino acid residues with absence of methionine, cysteine and abundant quantitites of glycine, glutamate asparate, serine and alanine. One mole of ornithine was detected per mole of putrescinin. Putrescine and spermidine was covalently bound to putrescinin; 3-5 moles of putrescine and 0.3-0.5 moles of spermidine/mole peptide. The conjugated polyamine content was 10-30 times that of free plasma polyamine. The significance of this peptide in coagulation and to CF will be discussed.