[Prostaglandin-H-synthase: stability and activity during immobilization on silica gel].

Prostaglandin H synthase was isolated in the form of microsomes from sheep vesicular glands and immobilized on silica gel. This system of prostaglandin synthesis was activated by calcium ions and stabilized by adrenaline. Microsomes immobilized in the presence of adrenaline and calcium ions were stable upon storage at 4 degrees C.

[Estradiol-binding properties of a sheep haptoglobin complex with hemoglobin. II. Preliminary data on quantitative characteristics of interaction].

The estradiol-binding properties of the sheep haptoglobin-hemoglobin complex (Hp-Hb) have been studied. The time and temperature dependencies of the steroid binding have been established the tightly bound 17 beta-estradiol, which is not detached from the complex during precipitation or extraction, has been shown to form a part of the total amount of the steroid capable of bending to Hp-Hb. Disturbances in the protein-protein interactions between Hp and Hb lead to the dissociation of estradiol as well as to the loss by the protein of its estradiol-binding activity.

[Identification of haptoglobin as an endogenous inhibitor of prostaglandin H synthetase in the cytosol of sheep vesicular gland cells].

It was shown that sheep vesicular gland cytosol inhibits the peroxidase activity of prostaglandin H synthetase (PGHS). The degree of enzyme inactivation depends on cytosol concentration and incubation time. It was found that cytosol contains a glycoprotein, haptoglobin, which is one of the cytosolic basic components responsible for its ability to inhibit PGHS.

Identification of haptoglobin as an endogenous inhibitor of prostaglandin H synthase in the cytosol fraction of primary cells from sheep vesicular glands.

It was shown that cytosol of primary sheep vesicular gland cells inhibits peroxidase activity of prostaglandin H synthase (PGHS). The degree of the enzyme inactivation depends on cytosol concentration. It was established that cytosol contains glycoprotein haptoglobin that is one of the cytosol basic components responsible for its property to inhibit PGHS.

[The effect of haptoglobin on prostaglandin H synthase from ram vesicular glands].

It was shown that the ability of sheep and horse haptoglobins differing in their immunological properties to inhibit PGH synthetase is about the same. It was found that haptoglobin inhibits the PGH synthetase-catalyzed enzymatic reaction, the inhibiting effect being non-competitive with respect to the electron donor, adrenaline. The degree of PGH synthetase inhibition by haptoglobin depends on the glycoprotein concentration, incubation time and enzyme activity.