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B M Nataf

Publications and source records attributed to B M Nataf.

17 recordsLinked to original sources
PubMed1978

Iodoamino acid composition of poorly iodinated human thyroglobulin fractionated by isopycnic centrifugation.

The distribution of iodotyrosines and iodothyroinines has been studied in poorly iodinated 19 S thyroglobulins isolated by sucrose gradient centrifugation from five human thyroid tissue. The 19 S thyroglobulins have been fractionated by isopycnic centrifugation and 34.5% rubidium chloride gradient. The distribution of iodoamino acids depends on the total iodine content of each fraction. The variations in MIT) and DIT residues with increasing levels of iodination are not identical, the elevation of DIT residues being higher than that of MIT. The number of T4 residues increases quite rapidly after 5 atoms of iodine while T3 increases slightly and slowly. It is shown here that, even after fractionation of poorly iodinated thyroglobulin, the synthesis of thyroid hormones is observed at a level of iodine content as low as 1.4 and 1.8 atoms per molecule of thyroglobulin. This shows that the thyroglobulin fractions obtained by isopycnic centrifugation are still heterogeneous, although less than the initial non-fractionated thyroglobulin. In order to explain our data, it must be admitted that a large proportion of thyroglobulin molecules are not iodinated.

Centrifugation, Density Gradient↗
PubMed1976

Thyroid peroxidase activity in iodine deficient rats.

The evolution of peroxidase activity was followed during the course of iodine deficiency in the rat. The enzymatic activity was determined in vitro by oxidation of iodide or by iodination of bovine serum albumin using a peroxide-generating system. An inverse relationship between the stable iodine content in the gland and the peroxidase activity is observed; this relation is not linear and the highest increase is found when the iodine content in the gland is below 5 mug per thyroid gland, at 35 days of the treatment. In animals maintained on a low iodine diet, a triphasic effect on enzymatic activity is observed: early (10 and 20 days) and late (70 and 80 days) effects when the increase in peroxidase activity is 3 times higher than the increase in weight, DNA and total protein content; and an intermediar effect (between 20 and 70 days) when the peroxidase activity says approximately at the same level. In any case, the enzymatic activity increases to a greater extent than do thyroid weight, and total protein and DNA content, suggesting that high cellular activity is due to a specific enzyme induction comparable to that we obtained recently in human sporadic goitre.

Animals↗