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Biomedical subjects

A Chrambach

Publications and source records attributed to A Chrambach.

At least 181 records · Page 10Linked to original sources
PubMed1977

Preparation of bio- and immunoactive human prolactin in milligram amounts from amniotic fluid in 60% yield.

Bio- and immunoactive human prolactin (hPRL) was isolated from amniotic fluid. The overall yield is a single passage through the procedure was 60%; 5 liters of amniotic fluid (10 mg hPRL) yielded 3 mg (30%) of a mixture of hPRL isohormones A, B (both minor), C and D (both major), and less than 10% contamination with extraneous protein. A further 3 mg hPRL was less highly purified. Two mg hPRL was recycled. The product has been stable for at least 1 year at--70 C, suitable for iodination, and gave rise to RIA dose-response curves indistinguishable from those obtained with pituitary hPRL. The isolated hormone, after stoichiometric iodination, is active in binding to both mammary gland and liver cell membrane receptors and exhibits a biological activity, in the local pigeon crop-sac assay, of 47.3 +/- 6.1 IU/mg. The isolation procedure consisted of 3 steps: 1) hollow-fiber dialysis to concentrate amniotic fluid; 2) gel filtration on Sephadex G-50 to remove bulk contaminants; 3)isoelectric focusing in a density gradient, taking advantage of the elevated isoelectric points, relative to contaminants, of hPRL isohormones (6.0-6.5, corrected). Production of this preparation, carried out on two separate occasions, required each time 3 months of a single investigator's time, inclusive of assay work.

Amniotic Fluid↗
PubMed1977

A catalogue of isohormones of human growth hormone based on quantitative polyacrylamide gel electrophoresis.

With the growing recognition that all polypeptide hormones exist in heterogeneous forms, i.e., isohormones, this study represents the initial development of a comprehensive catalogue of the various isohormone species of human growth hormone (hGH) in relation to molecular structure. The catalogue is based primarily on results obtained in quantitative polyacrylamide gel electrophoresis (PAGE) in a multiphasic buffer system optimized for characterization of hGH. Thus, hGH forms can be recognized in objective, numerical terms based on physicochemical parameters of molecular size and net charge. Isoelectric focusing in polyacrylamide gel; and PAGE in sodium dodecyl sulphate in the presence and absence of reducing agents supplement the quantitative PAGE criteria. Specific hGH immunoreactivity is necessary to completely distinguish hGH from hormones of similar size and charge properties (prolactin and chorionic somatomammotrophin). In the examination of eight standard hGH preparations obtained from four laboratories, all preparations exhibited multiple isohormone species, from two to five components per preparation. These identifiable components appear to represent the predominant species of a bidirectional continuum of hGH components, the continuum being in regard to both molecular size and charge. Within any given preparations, the continuum presents itself as a series of identifiable "charge isomers". Between preparations, in addition, there are size differences as well, which may relate to conformational changes (unfolding) in some preparations.

Electrophoresis, Polyacrylamide Gel↗
PubMed1976

Gram-preparative protein fractionation by isotachophoresis: isolation of human growth hormone isohormones.

Steady-state stacking (isotachophoresis) provides a preparative method in zone electrophoresis for the isolation of proteins in gram amounts. Up to four components were separated in 1000-fold larger quantities than those used in conventional electrophoresis. Separation occurs in order of free electrophoretic mobility. Recovery is nearly quantitative. The method was shown to be capable of resolving isohormones of human growth hormone. This fractionation is representative of difficult terminal isolations in biology. The best results are obtained when few components are fractionated at a high load. The method uses simple, small-scale apparatus. It does not utilize spacer ampholytes.

Buffers↗
PubMed1976

The binding of asparagine, glutamine and homoserine to human erythrocytes containing hemoglobins S and CS and to soluble hemoglobins S and CS.

Tritium labeled asparagine binds to oxyhemoglobin S and to a mixture of hemoglobins C and S in the molar ratio of 3.38:1 and 8.2:1 respectively. From the dialysis equilibrium studies it appears that labeled asparagine does not bind to oxy- or deoxy- hemoglobin A nor to deoxyhemoglobin S. The constant for equilibrium association of asparagine for oxyhemoglobin S is 7.38 x 10(7) M(-1) and for oxyhemoglobin CS 4.8 X 10(4) M(-1) at 23 degrees C. Tritium labeled asparagine is bound to oxyhemoglobin S and CS sufficiently strongly to prevent dissociation under the conditions of gel electrophoresis at pH 9.50. The protein with and without bound asparagine, glutamine or homoserine, is indistinguishable in molecular net charge and size by the criteria of quantitative polyacrylamide gel electrophoresis (PAGE). Also there were no significant differences in mobility between hemoglobin S and hemoglobin C in the presence and absence of asparagine, glutamine and homoserine as detectable in agar coated cellulose acetate electrophoresis at pH 6.3.

Asparagine↗
PubMed1976

Androgen binding proteins of testis, epididymis, and plasma in man and monkey.

Androgen-binding protein (ABP) has been found in the cytosol of testicular and epididymal homogenates of several sub-primate species. In those species which had the plasma androgen binding protein, testosterone-estradiol-binding globulin (TeBG), ABP and TeBG were found to be physically similar. We investigated the possibility that ABP might exist in monkey and man using the cytosol of testicular and epididymal homogenates and aspirates obtained by direct micropuncture of the rete testis. In polyacrylamide gel electrophoresis, pH 7.8, testicular and epididymal cytosols of monkey and man were found to contain several binding proteins of different size and net charge that bind dihydrotestosterone. These binding proteins were either indistinguishable from TeBG or could be related to TeBG as size and/or charge isomers. No ABP was detectable in up to 200 mul of monkey rete testis fluid obtained by direct micropuncture, though ABP is detectable in as little as 5 mul of rat rete testis fluid. The data suggest that the ABP's detected in the testicular and epididymal cytosols in monkey and man represent isomeric forms of plasma TeBG, and their presence in testicular cytosol most likely derives from blood contamination.

Androgens↗