Monoclonal antibody-directed immunopurification and identification of cytochromes P-450

A 28 amino acid peptide with diuretic and natriuretic activity has been purified from rat atrial muscle. The primary structure of this atrial peptide is H-Ser-Leu-Arg-Arg-Ser-Ser-Cys-Phe-Gly-Gly-Arg-Ile-Asp-Arg-Ile-Gly- (sequence in text) Ala-Gln-Ser-Gly-Leu-Gly-Cys-Asn-Ser-Phe-(Arg)-Tyr-OH. The biological activity of this peptide is identical to that of atrial natriuretic factor and cardionatrin I isolated from rat atria.     

Ultrastructural detection of the onset of pituitary thyrotroph sensitivity to lowered thyroid hormone concentrations in the fetal sheep

The goitrogen methylthiouracil was administered orally to pregnant ewes of known gestational ages to induce hypothyroidism in both mother and fetus. Developing pituitary thyrotrophic cells were studied using electron microscopy to detect the earliest gestational age at which morphological changes occurred in response to lowered plasma thyroid hormone concentrations. At 50 days of gestation, the pituitaries of fetuses exposed to the goitrogen were indistinguishable from untreated control glands. However, at 58 days and subsequent ages, "thyroidectomy' cells were observed in pituitaries of all hypothyroid fetuses. These findings indicate that fetal sheep pituitary thyrotrophs are sensitive to lowered thyroid hormone concentrations by 58 days of gestation, suggesting that thyroid-thyrotroph interaction exists at this early stage of development.     

Major polypeptide of duck hepatitis B surface antigen particles

The 40- to 50-nm pleomorphic particles found in the sera of domestic Pekin ducks infected with duck hepatitis B virus were purified by rate zonal and isopycnic centrifugation. Sodium dodecyl sulfate-polyacrylamide gel electrophoretic polypeptide analysis of these particles, called duck hepatitis B surface antigen particles, revealed the major component to be a single 17,500-dalton polypeptide. This result is in contrast to polypeptide analyses of the surface antigens of related mammalian viruses, including hepatitis B, in which a major doublet of polypeptides is seen with molecular weights ranging from 23,000 to 29,000. Tryptic maps of 17,500-dalton polypeptide resembled that of the major non-glycosylated polypeptide of the adw subtype of hepatitis B surface antigen. A serological assay for antibody to the purified duck virus particles is also described.     

Separation and properties of human brain hexosaminidase C

Hexosaminidase C was separated from human brain supernatant by immunoadsorption of the A and B forms on to a column of immobilized antibody followed by preparative starch-block electrophoresis. There were some differences in the properties of hexosaminidase C preparations after each of these stages, shown by comparison of their heat-inactivation characteristics and filtration through Bio-Gel P-200. The C form prepared by both separation steps had properties which differed markedly from those of the A and B isoenzymes; its molecular weight was much larger, greater than 200000, it had optimum activity between pH6 and 7 and could not be successfully eluted from DEAE-cellulose, even with high salt concentrations, or from Sephadex G-200. These results seem to support the proposal that the C form is under a separate genetic control from the others.