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Biomedical subjects

T McNabb

Publications and source records attributed to T McNabb.

8 recordsLinked to original sources
PubMed1977

Metabolism of estradiol by uterine peroxidase: nature of the water-soluble products.

The nature of the water-soluble products formed by incubating labelled estradiol with uterine peroxidase in the presence of H2O2 and tyrosine was examined by two-dimensional thin-layer chromatography and high voltage electrophoresis. It was shown that the steroid and amino acid were associated in a 1:2 or 1:3 ratio and evidence was provided by 3H-exchange for the interaction of tyrosine with ring A of estradiol at C-2 and C-4. The possible role of estrogen-induced peroxidase in the uterus in vivo is discussed.

Albumins↗
PubMed1976

Effect of nafoxidine (U-11,100A) on the induction of uterine peroxidase.

The relationship between the quantity of nuclear estrogen receptor complex formed and the amount of peroxidase induced by estradiol in immature rat uteri was determined. A good correlation was obtained between the quantity of 3H-estradiol specifically bound to the nuclear pellet and the amount of enzyme present 12 h after treatment with physiological doses of estrogen. Nafoxidine (U-11,100A) administered together with estrogen reduced signficantly the increase in peroxidase activity brought about by estradiol. Pretreatment with nafoxidine was less effective. The possible mechanism of action of this antiestrogen is discussed.

Animals↗
PubMed1976

Structure and function of immunoglobulin domains. V. Binding, University of immunoglobulin G and fragments to placental membrane preparations.

Fc receptors have been shown to be present in human placental tissue with properties distinct from those on macrophages and lymphocytes. A single class of receptor was observed with an intrinsic affinity 4X 10(6) M-(1) for human IgG1. The order of affinity for IgG subclasses was IgG1 = IGG1 greater than IgG3 greater than IgG4. IgA and IgM were not bound. Fc from IgG1 bound with the same affinity as the whole molecule and to the same number of receptor sites, 2 X 10 (12)/mg placental protein. IgG1 was no longer boung after mild reduction and alkylation whereas the binding of Fc was unaffected by this treatment. Neithe C3 nor C3, the two domains which comprise the Fc region of IgG1, bound to the placental receptor. This implies that this Fc receptor is unlike those found on most cell surfaces and that plasental binding is an exception to the theory that each domain has evoked to perform independent functions.

Binding Sites↗
PubMed1975

Purification and properties of oestrogen-induced uterine peroxidase.

1. An enzyme that can be induced in rat uteri by oestrogens and that catalyses the oxidation of guaiacol and the metabolism and binding of [4-14C]oestradiol to protein in the presence of H2O2 was partially purified by (NH4)2SO4 fractionation and polyacrylamide-gel chromatography. 2. The molecular weight of this uterine peroxidase was estimated to be about 40 000 and thus shown to differ from that of eosinophil peroxidase. 3. Cycloheximide, which blocks the increase in peroxidase activity brought about by oestrogen, was used to determine the half-life (about 4h) of the induced uterine enzyme.

Animals↗
PubMed1975

Effect of phenols on the oxidation of estradiol by uterine peroxidase.

The effect of various phenols on the conversion of [4 -14C]estradiol to water-soluble products by estrogen-induced uterine peroxidase (EC 1.11.1.7) has been investigated. Evidence was provided that those phenols which enhanced the oxidation of estradiol exerted their effect by activating peroxidase or protecting the enzyme from inactivation by the products of the reaction rather than by inhibiting the breakdown of hydrogen peroxide by catalase (EC 1.11.1.6). It has also been shown that tyrosine acted both as an activator of uterine peroxidase and as a water-soluble acceptor for the metabolites of estradiol. The ability of tyrosyl peptides to form conjugates with estradiol was influenced by the other amino acids and decreased with the number of adjacent tyrosyl residues.

Amino Acids↗