Abstract
Summary
In its natural state beta-inhibitor is complexed with the macroglobulin fraction of serum. When purified by adsorption-desorption, beta-inhibitor is a smaller molecular species in the range 80,000-100,000 molecular weight with a buoyant density of 1.3-1.4. The purified inhibitor is inactivated by trypsin, is heat labile and requires calcium ions, but is resistant to ether, chloroform and hydrazinie, is unaffected by sodium periodate, receptor destroying enzyme and beta-mercaptoethanol, and cannot be removed by antigen-antibody complexes. Virus can combine with the purified-inhibitor to prevent hemagglutination. Such virus-inhibitor complexes, however, cannot remove complement. From these data, beta-inhibitor apparently is a protein which can complex with macroglobulins. The staining of electropherograms with Sudan Black B and with periodic acid-Schiff reagent indicates the presence of lipid and carbohydrate, but the resistance of beta-inhibitor to ether and chloroform indicates that these substances do not appear to be essential for activity. Enhancement of inhibitory activity by treatment with beta-mercaptoethanol when the inhibitor is complexed with macroglobulin suggests perhaps that disulfide bonds may act to hold the complex together.
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