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Biomedical subjects

D C Teller

Publications and source records attributed to D C Teller.

At least 73 records · Page 4Linked to original sources
PubMed1979

Self-association of lyophilized horse liver alcohol dehydrogenase.

The molecular weights of lyophilized and non-lyophilized horse liver alcohol dehydrogenase have been compared by quasi-elastic light scattering, and ultracentrifugation. Whereas the non-lyophilized enzyme has the expected molecular weight of 78 000, the lyophilized enz)me has an initial molecular weight of about 10(6) which increases with time by an endothermic process. This result shows that any physical measurement using lyophilized liver alcohol dehydrogenase to investigate the enzyme mechanism, which relies upon the molecular size, will be invalid.

Alcohol Oxidoreductases↗
PubMed1978

Characterization of the sex steroid binding protein of human pregnancy serum. Improvements in the purification procedure.

The sex steroid binding protein (SBP) of human pregnancy serum was purified to homogeneity by the sequential use of ammonium sulfate precipitation, affinity chromatography on 5alpha-dihydrotestosterone-17beta-succinyldiaminoethyl-(1,4-butanediol diglycidyl ether)-agarose, and preparative polyacrylamide gel electrophoresis. The yield of pure SBP was improved from 5% as originally reported [Mickelson, K. E., and Petra, P. H. (1975), Biochemistry 14, 957] to 34%. Homogeneity of SBP was shown by equilibrium sedimentation ultracentrifugation in 6 M guanidine hydrochloride containing 0.1 M mercaptoethanol which yields a minimum molecular weight of 36 335 +/- 525. The protein is also homogeneous when examined by gel electrophoresis in the presence of sodium dodecyl sulfate. A value of 52 000 for the molecular weight is obtained by this method. SBP partially purified from Cohn fraction IV has also a molecular weight of 52 000 by gel electrophoresis in the presence of sodium dodecyl sulfate; that fraction is contaminated with another protein of molecular weight 90 000 which must be removed to obtain homogeneous SBP. The amino acid composition of SBP isolated from pregnancy serum is presented.

Amino Acids↗
PubMed1978

The evolution of histones.

The amino acid sequences of bovine histones H2A, H2B, H3, and H4 and the first 107 residues of rabbit thymus histone H1 were examined using newly developed procedures designed to detect and evaluate weak similarities (de Haën et al., 1976). Using the McLachlan scoring system, regions of statistically significant similarity were found between several pairs of the four smallest histones. The probability that this set of similarities could result simply from chance was estimated to be less than 10(-5). No similarity was found between the H1 sequence and the other histones. The results are interpreted to indicate that at least the C-terminal portions of the core histones evolved from a common ancestral protein.

Amino Acid Sequence↗
PubMed1977

Characterization of two species of Fc fragments obtained from rat IgG2a by prolonged papain digestion.

Prolonged papain digestion of rat IgG2a produced two molecular species of Fc fragments, termed Fc(I) and Fc(II). Studies by gel filtration chromatography and polyacrylamide gel electrophoresis in SDS/urea indicated that the two subunit polypeptide chains in each Fc preparation were associated by non-covalent bonds only. By analytical ultracentrifugation Fc(I) was found to have a m.w. of 47,100 and a sedimentation coefficient of 4.08S. Fc(II) had a m.w. of 39,800 and a sedimentation coefficient of 3.83S. The m.w. for the subunit chains of Fc(I) and Fc(II) were 25,300 and 20,300, respectively, as determined by analytical ultracentrifugation under dissociating conditions. Calculation of the frictional coefficient ratios indicated that both Fc fragments possessed compact globular structures. The difference in size between these two Fc fragments probably was due to a loss of some carboxy-terminal residues in Fc(II). Both Fc fragments possessed nearly identical amino-terminal amino acid sequences. Papain cleavage occurred primarily between residues 233/234 and 234/235. The carbohydrate compositions of the two species of Fc fragments were similar. It was concluded that under acid and reducing conditions papain cleavage of rat IgG2a occurred to the carboxy-terminal side of the hinge region. Prolonged papain digestion led to secondary attack in the carboxy-terminal end of the CGAMMA3 domain at an unidentified site, or sites, producing a stable second species of Fc fragments.

Amino Acids↗
PubMed1976

Physical properties of antitumor glutaminase-asparaginase from Pseudomonas 7A.

Glutaminase-asparaginase from Pseudomonas 7A appears to have four subunits with a molecular weight of 36,000 +/- 500 by sedimentation equilibrium in 5.9 M guanidine HCl and 34,000 by amino acid analysis. Analytic sedimentation equilibrium of the native enzyme showed a molecular weight of 140,000 +/- 3,300 with no signs of association or dissociation. Moving boundary and zone sedimentation in buffer showed normal behavior with sedimentation coefficients of 7.92 and 7.75 S, respectively. In contrast, the enzyme appeared to polymerize during zone sedimentation when the initial protein concentration was greater than 1 mg/ml and the buffer contained asparagine, glutamine, or 5-diazo-4-oxonorvaline. An extension of our method for active enzyme sedimentation is described which utilizes the changes in absorption during hydrolysis of asparagine by low concentrations of enzyme. Polymerization was not seen under these conditions.

Amino Acids↗
PubMed1976

Direct determination of the stoichiometry of charge transfer complexes.

The stoichiometry of the charge transfer complex between N-acetyl-L-tryptophan and 1-methylnicotinamide chloride has been determined to be precisely 1:1 by direct measurement of the molecular weight of the complex. The result is of interest both in terms of a general method for determining the stoichiometry of charge transfer complexes, and in terms of the probable stoichiometry of specific charge transfer complexes between 1-methylnicotinamide chloride and the exposed tryptophyl side chains of certain proteins. In the latter case, the result provides experimental proof for the assignment of extinction coefficients of specified magnitudes to the homomorphic model complexes which serve as the basis for the interpretation of results with proteins.

Binding Sites↗
PubMed1976

Characterization of human, bovine, and horse antithrombin III.

A comparison of the physical-chemical properties of human, bovine, and horse antithrombin III has been made. These three plasma proteins are strong inhibitors of bovine factor Xa and form a 1:1 molar complex with this coagulation enzyme. Human, bovine, and horse antithrombin III are glycoproteins containing hexose, hexosamine, and neuraminic acid. The total carbohydrate was 9, 12, and 16% for human, bovine, and horse antithrombin III, respectively. These proteins have a similar amino acid composition, although some monor variations were noted. Each antithrombin III is composed of a single polypeptide chain with an amino-terminal histidine residue. Of the first 17 amino-terminal residues, only three differences were noted between the three proteins. These occur in position 2 which is occupied by Gly, Arg, and Trp in human, bovine, and horse, respectively; position 6 which has a deletion in human antithrombin III; and position 8 where Ile in human and horse antithrombin III has been replaced by Val in the bovine preparation. The remainder of the first 17 residues is the same in all three proteins. The molecular weights for the bovine and horse preparation were 56 600 and 52 500, respectively, as determined by sedimentation equilibrium in the presence of guanidine hydrochloride. Some immunological cross-reactivity was also observed between the three different proteins.

Amino Acids↗
PubMed1975

A reexamination of the reaction between colchicine and tubulin.

The rate of reversible dissociation of the colchicine-tubulin complex has been determined for purified porcine brain tubulin and for sea urchin tubulin from 100,000 times g supernatant. The rate constant, which is essentially the same for both species, is extremely slow; it corresponds to a half-life of approximately 36 hours for the reaction. This rate was the same whether or not sucrose was present, and was not influenced by low concentrations of vinblastine or by millimolar concentrations of colchicine. The association rate constant was determined for porcine brain tubulin with and without CaCl2. The sample without CaCl2 had been maximally polymerized prior to the addition of colchicine. A 4.7-fold difference was observed between the association rate constants under these two conditions. Equilibrium constants calculated from the measured rate constants are 5 to 20 times greater than directly measured values; this suggests that the interaction of microtubules and colchicine is more complex than was previously thought.

Animals↗
PubMed1975

Biologic and physical properties of succinylated and glycosylated Acinetobacter glutaminase-asparaginase.

Acinetobacter glutaminase-asparaginase was chemically modified by succinylation and glycosylation with glycopeptides from human fibrin and gamma-globulin. These modifications markedly prolonged the half-lives of the enzyme in mice, rats, and rabbits. The plasma half-life in mice increased with decreasing isoelectric point. Glycosylation caused greater prolongation in rodents than succinylation. The kinetic properties of the modified enzymes were unchanged. Succinylation protected the enzyme from trypsin digestion. Glycosylated preparations had less heat inactivation than native and succinylated enzyme. Sedimentation equilibrium studies on a succinylated preparation showed reversible dissociation to a dimer (71, 400 g/mol) with an association constant of 1.3 times 10-6 liters/mol. This dissociation was identical with native enzyme, except for a 3% increase in molecular weight due to succinate groups. Sedimentation equilibrium studies on glycosylated preparations showed mixtures of molecular weight from 60, 000 to over 180, 000. Gel filtration and active enzyme sedimentation showed active polymers, but no active species smaller than tetramer.

Acinetobacter↗
PubMed1975

The molecular basis of self-association of IgG-Rheumatoid factors.

The intermediate complexes, sedimenting between 19S and 6.6S components of normal serum on analytical ultracentrifugation, were purified from plasma of three patients with rheumatoid arthritis. Sequential gel filtration and removal of contaminants by agarose-antibody immunoadsorbents were employed for purification of these complexes. The isolated complexes from the three patients consisted of IgG with k and lambda light chains. Sedimentation equilibrium ultracentrifugation experiments showed that the isolated complexes underwent concentration-dependent self-association, whereby the smallest detectable molecular species had a molecular weight of 292,000. These IgG dimers were formed by self-association of IgG-rheumatoid factors, since nearly all F(ab) fragments, prepared from the isolated complexes by pepsin digestion, bound to normal IgG. The association constants for the interaction between normal IgG and one binding site of the F(ab) fragments were about 10-5 liters/mole. Since a cyclic structure with two antigen-antibody bonds was thought to form in the self-association of two IgG-rheumatoid factors, the association constant for dimer formation was calculated to be 10-10 liters/mole. The preferential self-association of IgG-rheumatoid factor was supported by the observation that monomeric normal human IgG did not replace the IgG-rheumatoid factor when the complexes were dissociated and reformed in the presence of excess normal IgG. The self-association of IgG-rheumatoid factors may be a general phenomenon in rheumatoid arthritis, as suggested by the observations of other investigators.

Antibody Specificity↗
PubMed1974

The molecular basis of self-association of antibodies to IgG (rheumatoid factors) in rheumatoid arthritis.

The serum and synovial fluid of many patients with rheumatoid arthritis contain immune complexes composed of immunoglobulin G (IgG). In this study such complexes from one patient are shown to be formed by self-association of IgG-antibodies to IgG (IgG-rheumatoid factors), so that each molecule serves as an antibody as well as an antigen. All F(ab')(2) and Fab' fragments derived from these complexes have antibody binding sites for normal IgG. Due to a high association constant in the formation of a cyclic complex by these antibodies, normal IgG is excluded as an antigen. These studies serve as a model for further elucidation of presence of similar immune complexes in the serum and synovial fluid of patients with rheumatoid arthritis.

Antibodies, Anti-Idiotypic↗