Isolation and some properties of zinc-containing proteins from human placenta

Applying molecular filtration, the presence of two zinc-binding protein fractions in the human placenta was found. Their molecular weights were 47000 and 7900, respectively. A method for isolation of the high-molecular weight fraction from the placenta was elaborated. It consisted in the fractionation with acetone, Sephadex G-75 filtration, DEAE-Sephadex A-25 chromatography and preparative electrophoresis in polyacrylamide gel. It was calculated that 3.93 g-atoms of Zn are bound to one molecule of the protein. Rabbit antibodies against the zinc-containing protein formed an immunoprecipitate with the whole human amniotic fluid and with two protein fractions obtained following filtration of the amniotic fluids on Bio-Gel P-2.