[A study of the adhesive glycoprotein-inactivating protein from mammalian blood serum]

A protein with a molecular weight of 70 kDa was isolated from bovine blood serum and purified to a homogenous state. This protein inhibited reversibly the adhesive serum glycoprotein with a molecular weight of 12 kDa, which displayed biological activity at ultralow doses. Amino acid analysis showed that the protein inactivator belongs to the group of prealbumins from vertebrate blood serum. The secondary structure of its molecule was characterized by a considerable number of alpha-helices. The conditions for inactivation of serum glycoprotein were studied. The interaction between the serum glycoprotein and the protein inactivator occurred over a long period of time (1 day). It should be emphasized that the presence of calcium ions was a necessary condition for the inactivation of the serum glycoprotein. The data suggest that inactivation of serum glycoprotein results from the formation of a molecular complex consisting of the protein inactivator and the glycoprotein, which is related to the carbon-protein interaction.