Isolation and characterization of a polyamine-peptide conjugate from human amniotic fluid

Significant amounts of the diamine putrescine and the polyamines spermidine and spermine could be detected in human third-trimester amniotic fluid only after acid hydrolysis. This observation was interpreted to mean that these amines existed only in conjugated form in this biological fluid. Upon fractionation by ultrafiltration 90--10% of the putrescine was associated with the 1000--10 000 dalton fraction. Spermine was identified in this fraction and in a low-molecular weight fraction presumably representing acetylated derivatives. Spermidine was entirely associated with the 10 000--30 000 dalton fraction. The putrescine conjugate was purified to homogeneity by column chromatography on Biogels P10 and P6 followed by ion-exchange chromatography on DEAE-Sephadex A-25. Molecular weight by gel exclusion using peptide standards was estimated to be approx. 4600. The UV absorption spectrum of the putrescine conjugate conformed to that expected for a polypeptide. This putrescine conjugate contained 39 identified amino acids with a combined molecular weight of 4713. Putrescine was detectable by high pressure liquid chromatography only after acid hydrolysis of the conjugate. No other polyamines were detected in these hydrolyzates, nor were any polyamines demonstable in hydrolyzates of control peptides nor in pooled column washes. The identity of the putrescine determined by high pressure liquid chromatography was confirmed by a two-dimensional thin-layer chromatography method. These results establish the in vivo production of a putrescine--polypeptide conjugate in man. Such molecular species may constitute yet another metabolic pathway for polyamines or may reflect another mode of post-translational modification of polypeptide structure and function. The qualitative and quantitative analysis of polyamine conjugate in human aminotic fluid may prove to be useful in the detection of abnormalities in fetal development.

Extraction of human chorionic thyrotropin (hCT) from term placentas: failure to recover thyrotropic activity

We extracted human placentas by three methods to obtain chorionic TSH (hCT). The extracts were assayed by a sensitive homologous RIA for bovine TSH with an antibody which had veen used previously for assay of hCT. Based on the RIA for hCT, the yield of hCT was only 0.68 +/- 0.15 (SE) mU/100 g placenta by the Bates method, 2.01 +/- 0.35 mU/100 g by the Reisfeld method, and 4 mU/100 g by a Concanavalin A-Sepharose technique. Thyrotropic activity was detected by bioassay only in one Reisfeld extract; this biological activity could be attributed to hCG in this fraction. In TSH bioassays of other extracts, the responses were less than the sensitivity of the assay; some extracts were lethal to the bioassay mice. The low yield of hCT, about one-tenth to one-hundredth of that reported previously, casts doubt on the validity of the previous observations.