The interactions of the non-specific inhibitor of hyaluronidase with hyaluronidase and proteolytic enzymes in vivo

1. Following intravenous administration of testes hyaluronidase in rabbits and dogs, there is a decrease in the level of the non-specific inhibitor of hyaluronidase in serum. 2. If a large amount of hyaluronidase is injected, the inhibitor level is reduced to zero and hyaluronidase may be present in serum for some time after the injection. The hyaluronidase activity of such samples of serum increases when the serum is incubated with papain. 3. Hyaluronidase activity is found in the livers of the injected animals in large amounts and this activity is increased considerably when the homogenate of this tissue is incubated with papain. 4. Intravenous administration of several proteases or venom produces a decrease in the serum inhibitor level. Intravenous administration of streptokinase produces such a decrease in rabbits but not in dogs. 5. There is a correlation between the depletion of the inhibitor from the serum and the occurrence of a slow, persistent depression of blood pressure upon administration of proteolytic enzymes.     

Evidence that the serum inhibitor of hyaluronidase may be a member of the inter-alpha-inhibitor family

A study of the uncharacterized serum inhibitors of hyaluronidase, first described half a century ago, was undertaken. Activity was measured against bovine testicular hyaluronidase using a microtiter-based assay and reverse hyaluronan substrate gel zymography. The predominant inhibitory activity was magnesium-dependent and could be eliminated by protease or chondroitinase digestion and by heat treatment. Kinetics of inhibition were similar against hyaluronidases from testis and snake and bee venoms. The inhibitor had no effect on Streptomyces hyaluronidase, indicating that inhibition was not through protection of the hyaluronan substrate. Inhibition levels in serum were increased in mice following carbon tetrachloride or interleukin-1 injection, inducers of the acute-phase response. Reverse zymography identified a predominant band of 120-kDa relative molecular size, with two bands of greater and one of smaller size. The predominant protein was tentatively identified as a member of the inter-alpha-inhibitor family. Inhibition was also observed using either purified inter-alpha-inhibitor or an inter-alpha-inhibitor-related 120-kDa complex. Inter-alpha-inhibitor, found in the hyaluronan-rich cumulus mass surrounding mammalian ova and the coat of fibroblasts and mesothelial cells, may function to stabilize such matrices by protecting against hyaluronidase degradation. Turnover of circulating hyaluronan is extraordinarily rapid, with a half-life of 2-5 min. Prompt increases in levels of serum hyaluronan occur in patients with shock, septicemia, or massive burns, increases that can be attributed, in part, to suppression of degradation by these acute-phase reactants, the inhibitors of hyaluronidase.     

Antigenic and blood group activity of lamb gastric mucoproteins]

The antigenic properties of a lamb mucin and of a glycoprotein isolated from it are investigated. The proteins are studied by immunoelectrophoresis of the mucin and of the glycoprotein against either a sheep serum antiserum or an exclusively glycoprotein antiserum. No serum protein could be shown in the mucin. In addition, the glycoprotein gives a precipitin line only with the specific antiserum; its antigenic power seems to be concealed in the original mucin. The carbohydrates are studied through the investigation of the blood group activities by the hemagglutination inhibition technique. The mucin and the isolated glycoprotein show the same types of activities: they both prevent the agglutination of A1 and 0 red cells. The presence of two blood group activities in that glycoportein and its non-reactivity against A2 red cells corroborate the hypothesis that carbohydrate chains must be branched for the elicitation of these activities in a single molecule.