Jacquan Williams

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Screening of human serum samples by polyacrylamide-gel electrophoresis in the presence of 6 M-urea revealed an individual who is heterozygous for a variant transferrin. The variant transferrin is able to bind two atoms of iron, but the iron in the C-terminal binding site is bound abnormally, as judged by its spectral properties, and is dissociated from the(More)
The Makey & Seal [(1976) Biochim. Biophys. Acta 453, 250--256] method of polyacrylamide-gel electrophoresis in buffer containing 6 M-urea was used to determine the distribution of iron between the N-terminal and C-terminal iron-binding sites of transferrin in human serum. In fresh serum the two sites are unequally occupied; there is preferential occupation(More)
1. Hen ovotransferrin was examined by isoelectric fractionation. 2. The major component observed in starch-gel electrophoresis can be isolated from the minor component. 3. When non-saturating amounts of iron are added to ovotransferrin, isoelectric fractionation demonstrates the existence of three molecular species corresponding to the metal-free protein,(More)
1. When iron-saturated hen ovotransferrin was treated with subtilisin the N-terminal half was digested at a faster rate than the C-terminal half, allowing the latter to be isolated as a single-chain fragment of mol.wt 35000. 2. In mildly acid conditions iron-ovotransferrin loses iron preferentially from its N-terminal binding site. Trypsin digestion of the(More)
Five alpha-D-galactosidases (alpha-D-galactoside galactohydrolase; EC 3.2.1.22) have been identified by chromatography and polyacrylamide-disc-gel electrophoresis in the germinated seeds of Trifolium repens (white clover). alpha-Galactosidase I has been purified to homogeneity with an approx. 2000-fold increase in specific activity. The enzyme was purified(More)
Brief treatment of iron-saturated hen ovotransferrin with dithiothreitol selectively cleaves the disulphide bridge between residues 478 and 671, which is in the C-terminal domain of the protein. The reduced alkylated protein is less stable than the native protein, and its iron-binding properties are different. A fluorescent derivative was prepared by(More)
Polynuclear aromatic hydrocarbons (PAHs) present in tobacco smoke are regarded as chemical carcinogens. Previously, we observed that a weakly acidic phenolic fraction of tobacco smoke condensate (TSCPhFr), which is devoid of PAHs, significantly potentiates (±)-anti-BP-7,8-diol-9,10-epoxide (BPDE)-induced anchorage-independent cell growth of(More)
The structure of apo duck ovotransferrin (APODOT) has been determined at a resolution of 4.0 A by the molecular replacement method using the structure of duck ovotransferrin (DOT) as the search model. The DOT structure contains two iron binding sites; one in the N-terminal lobe lying between domains N1 and N2 and one in the C-terminal lobe between domains(More)
Five alpha-galactosidases (alpha-D-galactoside galactohydrolase, EC 3.2.1.22) were identified by chromatography and by their different electrophoretic mobilities, in the germinated seeds of Trifolium repens (white clover). alpha-Galactosidases II, III and IV were purified to homogeneity, with increases in specific activity of approx. 4600-, 4900- and(More)
The dependence of the metal-binding properties of transferrin on pH in the pH 6--9 range was investigated by urea/polyacrylamide-gel electrophoresis. Equations are presented for calculating the relative values of the four conditional site constants for the stepwise binding of iron to the two sites of transferrin and for calculating the equilibrium(More)