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E Ankel

Publications and source records attributed to E Ankel.

7 recordsLinked to original sources
PubMed1985

Preparation of functionally intact monomers by limited disulfide reduction of human plasma fibronectin dimers.

Most (90 to 95%) human plasma fibronectin (PFn) molecules exist as 450-kDa disulfide-rich dimers comprised of two major types of subunits (A, 220 kDa; B, 215 kDa) that are joined near the COOH terminus by two disulfide bonds. Smaller PFn species (Zone II; 190-235 kDa) consist mainly of monomers and/or a monomeric subunit joined covalently to a smaller peptide remnant presumably derived by proteolysis of a parent 450-kDa molecule. A relatively simple and selective method for preparing functionally active, partially reduced monomeric fibronectin subunits (PR-PFn) by limited and selective reduction of dimeric plasma fibronectin (PFn) has been developed. PR-PFn was prepared by incubating PFn in phosphate-buffered saline, pH 7.4, for 2 h at room temperature in the presence of 17 mM dithiothreitol (DTT). Following S-carboxymethylation or S-carboxyamidomethylation, the material was passed through a gelatin-Sepharose column and nonbinding material was discarded; gelatin-bound material was eluted using a 0 to 2 M KSCN gradient. Residual dimeric species (10-20%) could be separated from monomers in high yield by gel-sieving chromatography on a Sepharose 6B-Cl in the presence of a chaotropic salt, 0.3 M KSCN. Most new SH groups (74-81%) in that fraction of PR-PFn binding to gelatin were localized in proteolytic fragments containing the COOH terminus, thus suggesting that selective cleavage of the interchain disulfide bridges had taken place. The binding affinity of PR-PFn to gelatin- and fibrin-Sepharose was lower than that of dimeric PFn, but the same as that of Zone II PFn and other monomeric gelatin-binding proteolytic derivatives. PR-PFn also bound to heparin-Sepharose and promoted cell attachment and spreading. We conclude that PR-PFn monomers possess the same functional activities as those of the parent chains.

Chromatography, Affinity↗
PubMed1979

Comparative cytotoxic and biochemical effects of ligands and metal complexes of alpha-N-heterocyclic carboxaldehyde thiosemicarbazones.

Several alpha-N-heterocyclic carboxaldehyde thiosemicarbazones and their iron and copper complexes have been tested for their cytotoxicity and inhibiting activity against DNA synthesis under controlled metal conditions. No ligands show cytotoxicity against Ehrlich cells at the concentrations tested, while some iron and copper complexes are active. In contrast, the ligands inhibit DNA synthesis at much lower concentrations than used above. Similarly, the metal complexes are effective inhibitors at concentrations much below those necessary to demonstrate cytotoxicity. In addition, the iron complexes of 1-formylisoquinoline thiosemicarbazone, 2-formylpyridine thiosemicarbazone, and 4-methyl-5-amino-1-formylisoquinoline thiosemicarbazone were shown to be three- to sixfold more active than their free ligands as inhibitors of partially purified ribonucleotide reductase to which no iron has been added. The copper complex of 2-formylpyridine thiosemicarbazone was slightly more active than the free ligand against the reductase.

Animals↗