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Biomedical subjects

R Wetzel

Publications and source records attributed to R Wetzel.

At least 91 records · Page 5Linked to original sources
PubMed1981

Properties of a human alpha-interferon purified from E. coli extracts.

A human alpha interferon, designated HuIFN-alpha A, produced in E. coli by direct expression of cloned cDNA [Goeddel et al., Nature 287, 411--416 (1980)] has been purified from bacterial extracts and characterized. The protein has a molecular weight (19,400 by SDS/PAGE) and amino acid composition consistent with the DNA sequence. The pI was determined to be 6.1. The molecule has a specific activity of 1.5 x 10(8) NIH reference units/mg of protein. The sequence of the first 35 amino acids is identical to that expected from the nucleotide sequence. About 50% of the molecules begin with the expected cysteine, and 50% begin with the initiator methionine which E. coli apparently did not remove efficiently. Analysis of a trypsin digest of the native molecule showed that all four of the molecule's cysteines are involved in disulfide bonds: Cys1 is bonded to Cys98, and Cys29 is bonded to Cys 138.

Amino Acids↗
PubMed1980

Production of biologically active N alpha-desacetylthymosin alpha 1 in Escherichia coli through expression of a chemically synthesized gene.

Thymosin alpha 1, an immune restorative polypeptide hormone, was synthesized in Escherichia coli by using recombinant DNA cloning techniques. Based on the known amino acid sequence, a gene coding for the thymosin alpha 1 polypeptide chain was designed and enzymatically assembled from chemically synthesized oligodeoxyribonucleotide fragments. The gene was ligated into plasmid pBR322 and placed under lac operon control, and N alpha-desacetylthymosin alpha 1 was expressed as part of a beta-galactosidase chimeric protein. Cyanogen bromide cleavage of this protein gave a mixture of polypeptides, among which thymosin alpha 1 activity was detected by radioimmunoassay (RIA). The E. coli product is identical with native thymosin alpha 1 isolated from calf thymus in the amino acid sequence but lacks the N-terminal acetyl group. Results of a guinea pig migration inhibition factor (MIF) assay, a terminal deoxyribonucleotidyl transferase (TdT) assay, and radioimmunoassay indicate that the N alpha-desacetylthymosin alpha 1 produced by deoxyribonucleic acid (DNA) cloning techniques has biological activity equivalent to that of the native hormone.

Amino Acid Sequence↗
PubMed1980

Temperature behaviour of human serum albumin.

Structural alterations of albumin, their dependence on concentration and the role of free --SH groups at thermal denaturation, as well as the reversibility of thermally induced structural changes, were studied. Application of various physical methods provides information on a series of structural parameters in a major concentration range. Apart from changes of the helix content, heat treatment gives rise to beta structures which are amplified on cooling and which are correlated with the aggregation of albumin. With rising temperature and concentration the proportion of beta structures and aggregates increases. At degrees of denaturation of up to 20% complete renaturation is possibly in every case. The structure content is concentration-dependent even at room temperature. It may be that intermolecular interactions induce additional alpha-helix structures which are less stable, however, than the ones stabilized by intramolecular interactions. Unfolding of the pocket containing the free --SH group of cysteine-34 enables disulphide bridges to be formed leading to stable aggregates and irreversible structural alterations. Through binding of N-ethymaleimide to free --SH groups, which blocks the formation of disulphide bridges, it is possible to prevent aggregation and irreversible conformational changes. At temperatures below 65--70 degrees C, oligomers are formed mainly via intermolecular beta structures.

Circular Dichroism↗
PubMed1979

Identification and nucleotide sequence of the sup8-e UGA-suppressor leucine tRNA from Schizosaccharomyces pombe.

Using the translation of rabbit globin mRNA in wheat germ extracts as an assay for ochre and opal suppression, a UGA suppressor tRNA from Schizosaccharomyces pombre strain sup8-e was purified by column chromatography and two-dimensional gel electrophoresis. The purified tRNA can be aminoacylated with leucine by a crude aminoacyl-tRNA synthetase preparation from a wild type S. pombe strain, and has high activity in the suppressor assay. By a combination of post-labeling fingerprinting and rapid gel sequencing methods the nucleotide sequence of this suppressor tRNA was determined to be: pG-C-G-G-C-U-A-U-G-C-C-ac4C-G-A-G-D-G-G-D-G-D-A-A-G-G-G-m22G-G-C-A-G-A-psi-U-U*-C-A-m1G-C-C-C-U-G-C-U-G-U-U-G-U-A-A-A-A-C-G-m5C-G-A-G-A-G-T-psi-C-G-m1A-A-C-C-U-C-U-C-U-G-G-C-C-G-C-A-C-C-AOH. The anticodon sequence U*CA is complementary to the UGA codon. An interesting feature of the suppressor tRNA is an expanded anticodon loop of nine nucleotides owing to an A-C nonpair at the first anticodon stem position.

Ascomycota↗
PubMed1978

Aminoacyl-tRNA synthetase families and their significance to the origin of the genetic code.

A correlation of various aspects of the protein structures and substrate and mechanistic specificities of the aminoacyl-tRNA synthetases has led to the identification of at least one family of enzymes probably derived from a common ancestral synthetase. While strong correlations exist only in one part of the array of 64 codons comprising the Genetic Code, this itself may be interpreted as a meaningful pattern, most consistent with a development of the present code from earlier codes containing fewer amino acids and fewer available codons. Specifically, strong correlations in the enzymes whose cognate tRNAs respond to codons containing a central pyrimidine, including the enzyme family of Ile-, Phe-, Val-, Met-, and Leu-tRNA synthetases, suggests that these enzymes evolved last, and that, therefore, an earlier version of the Genetic Code was comprised solely of codons containing a central purine. It is suggested that further study of the historical interrelationships of these enzymes could lead to a fairly detailed picture of how the Genetic Code developed.

Amino Acyl-tRNA Synthetases↗
PubMed1978

[Behavior of the trace elements copper, zinc and manganese in bovine rumen. 1. Trace element content of different fractions of rumen fluid and the effect of copper sulfate administration].

Two adult, rumen-fistulated steers were fed, over four consecutive 3-week periods, Cu-deficient and normal hays with and without copper sulphate supplementation. Their rumen liquor levels of copper, zinc and manganese were determined correspondingly. The rumen liquor samples were split into 3 fractions by way of centrifugation, sodium dodecyl sulphate treatment of the sediment and filtration. The fractionation of the rumen liquor showed copper to be contained mainly in the water-soluble supernatant (68%), whilst zinc and manganese are more strongly linked to the microbial fraction (57 and 46%, resp.). The plant residue did not average but 9, 24 and 22% of copper, zinc and manganese, respectively. Copper sulphate supplementation to normal hay resulted in a significantly increased copper content in the supernatant and in the microbial fraction. At the same time, the zinc and manganese content values in the microbial fraction were found increased. However, the same copper sulphate supplementation to Cu-deficient hay was found to reduce highly significantly the copper level in the microbial fraction. It is supposed that the excessively high molybdenum content of this hay (2.5 ng/kg) has prevented any effect of the copper sulphate supplementation. The positive effects of copper sulphate supplementation on the zinc and manganese levels in the bacterial fraction were maintained even when feeding Cu-deficient hay rich in Mo.

Animal Feed↗
PubMed1978

[Behavior of trace elements copper, zinc and manganese in bovine rumen. 2. Passage rate and course of trace element concentration in rumen as influenced by copper sulfate administration].

In experiments on the distribution of copper, zinc and manganese in fractions of rumen liquor (Wetzel and Menke, 1977 (1)) changes in PEG and in trace element concentration during day-time (between 8 a.m. and 6 p.m.) were measured at 2-hour intervals. Rumen volume was 61 l and passage rate 108 and 128 l/day in the two animals used. Average daily passage was calculated to be 40 mg copper, 98 mg zinc and 371 mg manganese. These values were found to be 11% higher than copper intake and 44 and 68% lower than zinc and manganese intakes, respectively. The differences indicate a remarkable endogenous secretion of copper, and a high absorption of zinc and manganese within the rumen. Concentration (mcg/g dry matter) of copper, zinc and manganese in the bacterial fraction and in total rumen liquor decreased slowly in the first hours after feeding, reaching a minimum after 4 to 6 hours and showed a slight increase thereafter. After addition of copper sulphate the curves mostly became linear. The conclusion is drawn that 1.8 ppm copper in inorganic binding does not lead to changes in trace element concentration to an extent that might be harmful to bacterial fermentation.

Animals↗
PubMed1977

Analogs of methionyl-tRNA synthetase substrates containing photolabile groups.

Three photolabile analogs of substrates of methionyl-tRNA synthetase were synthesized. In one, the 4-thiouridine at the 8 position of E. coli tRNAfMet was alkylated with [14C]p-azidobromoacetanilide. In the second, [14C]p-azidobenzoic acid hydrazide was condensed with the 3'-terminal dialdehyde of periodate-oxidized Escherichia coli tRNAfMet. The modified tRNAs could be purified by chromatography on benzoylated DEAE-cellulose. The third photolabile compound was [3H]methioninyl-8-azido-adenosine 5'-phosphate, an analog of the methionyl adenylate intermediate in the aminoacylation reaction. Irradiation of each of these compounds in the presence of equimolar amounts of E. coli methionyl-tRNA synthetase of micrometer concentrations gave 5-15% crosslinking.

Affinity Labels↗
PubMed1977

Psychiatric illness and non-cancer hysterectomy.

Forty-nine randomly selected women who received hysterectomy for reasons other than cancer were studied preoperatively with systematic interviews and record reviews, and were diagnosed using the explicit criteria of Feighner, et al. Fifty-seven percent were found to be psychiatrically ill, with 27% suffering from hysteria (Briquet's Syndrome), and 18% from primary depression. Recently some investigators have attributed a "post-hysterectomy syndrome" characterized by multiple psychologic and somatic symptoms to the surgery itself. However, a high pre-operative prevalence of psychiatric illness, particularly hysteria, must be considered when evaluating symptoms in a post-hysterectomy population.

Adult↗
PubMed1975

A facile method for the preparation of N6-substituted ATP-Sepharose.

The attachment of 6-methylsulfonylpurineribose 5'-triphosphate to AH-Sepharose 4B as a facile method for the preparation of ATP-Sepharose is described. This reaction is compared to the coupling of 6-chloropurineriboside 5'-triphosphate as well as N(6)-aminocaproyl-ATP. An improved synthesis of purineriboside 5'-phosphates which does not require purification by column chromatography is also described.

Adenosine Triphosphate↗