Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.11.1.7 (peroxidase)
65,474 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The assay of FSH by a radioligand receptor assay (RLA) using homogenates of rat testicular tissue incubated for 17 h at 21 degrees C has been assessed. Chloramine-T or lactoperoxidase were used for iodination. The assay gave linear dose-response lines between 30 and 2000 ng sheep FSH/tube, and there was usually no major interference by LH. Two batches of labelled FSH, however, gave assays in which LH showed a striking interaction with FSH. When these batches were avoided and FSH and LH were mixed in ratios that differed less than fourfold, the assay was combined successfully, in the same tubes, with an RLA for LH, using LH and FSH labelled with 131I and 125I respectively. The RLA for FSH was not suitable for assay of FSH in rat serum because of apparent non-specific interference. Assay by RLA of rat FSH, in pituitary homogenates or released during incubation in vitro, gave results which were not closely correlated with those of either conventional bioassay or radioimmunoassay.
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PMID:Radioligand receptor assay of FSH. 18 33

Purified virions of the GS strain of the BK group of human papovaviruses were labeled with 125I using chloramine T or lactoperoxidase or with tritium using sodium borohydride. All viral polypeptides were labeled. Tryptic digests of iodinated VP1 were analyzed.
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PMID:Radioisotopic labeling of human papovavirus (BK) by iodination and reductive alkylation. 18 24

A highly specific and simple radioimmunoassay for cyclic AMP with a sensitivity of 0.04 picomoles/tube has been developed according to the method of Steiner et al., using 125I-succinyl cyclic AMP tyrosine methyl ester as a tracer. The tracer with higher immunoactivities could be simply and constantly prepared by an enzymatic iodination procedure utilizing lactoperoxidase, radioactive iodide and hydrogen peroxide generated by glucose-glucose oxidase system, rather than by chloramine-T procedure.
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PMID:Enzymatic radioiodination of succinyl cyclic AMP tyrosine methyl ester by lactoperoxidase and radioimmunoassay for cyclic AMP. 18 59

1. Isolated mouse spleen lymphocytes hydrolysed UDP-galactose added to the medium. Nucleotide pyrophosphatase activity that accounted for this hydrolysis was enriched to a similar extent as alkaline phosphodiesterase and 5'-nucleotidase in a lymphocyte plasma-membrane fraction. 2. The cell surfaces of mouse spleen and thymus lymphocytes were iodinated with 125I by using the lactoperoxidase-catalysis method. Detergent extracts of the cells were mixed with a purified anti-(mouse liver plasma-membrane nucleotide pyrophosphatase) antiserum and the immunoprecipitates analysed by polyacrylamide-gel electrophoresis. Only one major radioactive component, similar in size (apparent mol.wt 110000-130000) to the liver enzyme, was observed. 3. Electrophoresis of an iodinated spleen plasma-membrane fraction indicated peaks of radioactivity, including one of apparent mol.wt 110000-130000. 4. When detergent extracts of spleen lymphocytes were passed through a Sepharose-bead column containing covalently attached anti-(nucleotide pyrophosphatase) antiserum, the nucleotide pyrophosphatase activity was retained by the beads, whereas protein and leucine naphthylamidase activity were eluted. 5. The results indicate that nucleotide pyrophosphatase and alkaline phosphodiesterase activities are due to the location of the same or similar enzymes at the outer aspect of the lymphocyte plasma membrane. Some possible functions of enzymes at this location are discussed.
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PMID:Location of nucleotide pyrophosphatase and alkaline phosphodiesterase activities on the lymphocyte surface membrane. 18 74

Bordetella pertussis strain number 18334 was grown in media which yielded cells with either a normal complement of surface antigens (X-model), or cells which were phenotypically altered (C-model). Neither X- nor C-mode bacteria incorporated more than traces of radioactivity when exposed to Na 125 I, lactoperoxidase and a source of H2O2 under conditions which gave substantial labelling of BSA and other soluble proteins. In contrast, envelope preparations were readily labelled. Analysis by sodium dodecyl sulphate-polyacrylamide gel electrophoresis showed that several polypeptides had incorporated 125 I but not in amounts proportional to their abundance in the envelopes. Envelopes from C-mode cells gave a labelling pattern similar to those of X-mode except in one region. Control experiments suggested that the failure of intact cells to become labelled may be due to bacterial inhibition of the reagents.
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PMID:Radiolabelling of Bordetella pertussis envelope proteins by the 125 I-lactoperoxidase method. 18 62

A radioimmunoassay for plasma ACTH has been developed utilizing highly purified human ACTH (Li) labelled with 125I by the lactoperoxidase method as a tracer and an ACTH antibody produced by immunization of rabbits with ACTH-Z (Organon). The assay is highly specific, reproducible and sensitive to 20 pg of ACTH per ml. Utilizing this technique, endogenous ACTH secretion, adrenal responsiveness to endogenous ACTH and hypothalamic pituitary adrenal feedback mechanisms have been assessed in normal subjects and in patients with Cushing's syndrome due to adrenocortical hyperplasia and nodular cortical hyperplasia. The potential effect of a negative feedback mechanism on the circadian rhythmicity after SU-4885 administration was assessed by initiating SU-4885 either at 9 p.m. or 8 a.m. In normal subjects, the circadian rhythm of ACTH was persistent and independent of a decrease in cortisol. However, in a single case of Cushing's syndrome due to adrenocortical hyperplasia, the circadian rhythm was different from that of normal subjects, possibly influenced by a negative feedback mechanism when SU-4885 was initiated at 8 a.m. In Cushing's syndrome due to adrenocortical and nodular cortical hyperplasia, a significant correlation was observed between the mean plasma ACTH and urinary 17-OHCS values before and after SU-4885 administration (r=0.743, p less than0.01). A significant correlation was also obtained in normal subjects between plasma ACTH and urinary 17-OHCS values (r=0.889, p less than 0.01). However, there was quantitatively more 17-OHCS excreted in the urine for a given plasma ACTH level in patients with Cushing's syndrome than in normal subjects. To assess the relative biological activity of endogenous and exogenously administered ACTH, the ratio of daily 17-OHCS during SU-4885 administration and Cortrosyn-Z administration was expressed as the Cortrosyn Equivalent Quotient (C.E.Q.). The correlation between plasma ACTH and C.E.Q. was similar and significant for normal subjects and patients with Cushing's syndrome (r=0.670, p less than 0.01). These data suggest that there is hyper-responsiveness of the adrenal glands to endogenous ACTH in Cushing's syndrome due to adrenocortical hyperplasia and nodular cortical hyperplasia and that the adrenal hyperactivity is not engendered by a qualitative change in the ACTH release from the pituitary gland. To assess pituitary suppressibility, dexamethasone was administered 40 days or more later following total adrenalectomy in 9 patients with Cushing's syndrome, 6 with adrenocortical hyperplasia and 3 with nodular cortical hyperplasia. One day after discontinuation of substitution therapy, 2 mg of dexamethasone was administered orally followed on successive days by 4 and 8 mg doses. In each instance, dexamethasone was given at midnight and the plasma ACTH concentration was determined at 9:00 a.m. on the day before and after administration of the dexamethasone. A patient with Addison's disease was studied as a control...
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PMID:[ACTH secretion and adrenocortical responsiveness in Cushing's syndrome due to adrenocortical hyperplasia (author's transl)]. 19 54

The natural opiate methionine-enkephalin and its D-alanine2 analog were iodinated by a method involving lactoperoxidase and purified by partition chromatography on Sephadex G-25. The half-time disappearance of radioactivity was determined in blood obtained from the jugular vein after injection of the iodinated methionine-enkephalin into the carotid artery or jugular vein and found to be less than a minute. Despite a greater potency and more prolonged activity of D-alanime2-methionine-enkephalin as compared with methionine-enkephalin, the half-time disappearance of radioactivity after injection of the iodinated analog was about the same, its distribution volume tended to be smaller, and the retention of counts in the brain was significantly less then after the iodinated parent compound. There was little statistical difference in the accumulation of radioactivity among nine brain regions 5 sec after the rapid injection of tritiated methionine-enkephalin into the carotid artery in contrast with the accumulation found after similar injection of tritiated tyrosine or tritiated water. The ratio of radioactivity in the pituitary or pineal to that in the brain parts within the blood-brain barrier was much greater after administration of the tritiated enkephalin than after the tritiated water. A modified brain-uptake index (BUI) value of 15 for the tritiated enkephalin indicates that methionine-enkephalin crosses the blood-brain barrier.
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PMID:Blood-brain barrier, half-time disappearance, and brain distribution for labeled enkephalin and a potent analog. 19 Nov 53

The interaction between mouse choriomammotropin and mouse mammary glands was examined by radioreceptor assays using ovine prolactin (NIH-P-S9) iodinated by lactoperoxidase as a tracer. Mouse pituitary extracts and placental extracts were subjected to 10% acrylamide gel electrophoresis. Gels were cut into 2-mm segments after electrophoresis, and stored in 1 ml 0.05 M phosphate buffer (pH 7.4) containing 0.05 M NaCl overnight for elution. Lactating mammary tissues from D strain mice were incubated for 120 min in 1 ml Medium 199 containing 6 ng of 125I-prolactin and 0.1 ml of each eluate. Pituitary extracts displaced 125I-prolactin only at the position which coincides with the prolactin band. Displacement was observed at two positions of the gel when placental extracts were used. Relative mobilities (Rm) were 0.21 and 0.71, respectively. The slowly migrating component of choriomammotropin inhibited the binding of 125-I-prolactin more strongly that the rapidly migrating one. Neither of them was identified as a distinct band in stained gels. The molecular weight of ovine prolactin, mouse pituitary prolactin and the slowly migrating component of mouse choriomammotropin was estimated to be 23000 using disc electrophoresis but the ion charges of these hormones were considerably different.
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PMID:Binding of mouse choriomammotropin to prolactin receptors in the mouse mammary gland. 19 Dec 49

Human red blood cells were treated with phospholipase C from Clostridium welchii. Lipase concentrations which produced less than 1% hemolysis and 10-15% hydrolysis of the membrane phospholipids reduced markedly (greater than 80%) the accessibility of membrane proteins to the external surface as measured by lactoperoxidase-catalyzed iodination.
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PMID:Decreased iodination of the red cell surface following phospholipase C treatment. 19 10

Ovine prolactin was iodinated by the lactoperoxidase method and purified by gel filtration on Sephadex G-100. The binding ability of the labelled hormone was determined, by incubation with liver homogenate from rabbits in late pregnancy, to be 8-8% total binding/mg protein, of which 86% was specific. The fraction of 125I-labelled ovine prolactin which bound most strongly was subsequently used to study its binding to rat seminal vesicle, prostate and testicular homogenates. The total binding to the seminal vesicle homogenate taken from mature (80-day-old) rats was the highest (11-69%/mg protein), but the greatest degree of binding specificity (82-6%) was to immature (30-day-old) rat prostate. Both total and specific binding to rat testicular homogenate were consistently very low. The binding specificity was demonstrated by displacement studies: while ovine prolactin caused displacement of specific binding, human chorionic gonadotropin, rat thyrotropin and human follicle-stimulating hormone did not cause any significant displacement of bound 125I-labelled ovine prolactin. Affinity constants (Ka) and binding capacities for the seminal vesicle and prostate homogenates were determined by Scatchard analysis and the effect of age on these parameters was studied. There was no difference in Ka between the aged (220-day-old), immature and mature rat tissue homogenates; however, a significant fall in binding capacity was observed in the mature rat prostate, and a further fall in the aged rat prostate. No such change was observed in the binding capacity of the seminal vesicle, as estimated by Scatchard analysis, although total and specific binding to the mature homogenates was higher than that of the other age groups.
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PMID:Specific binding of prolactin to seminal vesicle, prostate and testicular homogenates of immature, mature and aged rats. 19 87


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