A discontinuous gradient of Percoll was used to remove RBCs from polymorphonuclear leucocyte (PMN) preparations. The resulting red blood cell-free preparation was used to investigate the effect of ammonium chloride on the iodination response of human PMN. Treatment of PMN with ammonium chloride for five minutes at room temperature resulted in a statistically significant increase in the iodinati...

1. A method is described for the trace iodination of immunoglobulins and other serum proteins by a system consisting of lactoperoxidase, hydrogen peroxide and iodide. 2. gammaG immunoglobulin that had been labelled to a specific radioactivity of 5muc/mug. by use of carrier-free [(125)I]iodide gave no evidence of denaturation when analysed by electrophoresis and density-gradient ultracentrifugat...

A double labeling procedure was employed to determine whether the tyrosine residues in thyroglobulin that are iodinated first are also those that are most readily converted to thyroxine. Goiter thyroglobulin containing less than 1 atom of iodine per molecule was iodinated first with 9 at relatively low levels of iodination (5 to 20 atoms of iodine per molecule) and afterward with lzjI at higher...

Introduction The conversion of tyrosyl residues into iodo-derivatives can be brought about under different ex­ perimental conditions [1 -3 ] and is essentially an electrophilic substitution by iodine at the phenolic ring of tyrosine. This reaction has been performed for different purposes in protein chemistry, e.g. the iodination of tyrosine has been extensively used in the preparation of label...

The photoaffinity analog 2-azido-AMP was found to be a potent allosteric inhibitor of pig kidney fructose 1,6-bisphosphatase. UV-induced covalent incorporation of 2-azido-[8-3H]AMP fully inactivated the enzyme at a level stoichiometric with its subunit composition (4 mol of analog/mol of tetramer). The photoincorporation and inactivation were prevented by the presence of AMP but not by the subs...

Based on a literature precedent, preparation of methyl 4-azido-3,4,6-trideoxy-3-fluoro-alpha-D-mannopyranoside (18) was attempted via fluorination of methyl 4-azido-2-O-benzyl-4,6-dideoxy-alpha-D-altropyranoside with diethylaminosulfur trifluoride (DAST). Contrary to expectations, the reaction took place with retention of configuration at the site of the fluorination yielding methyl 4-azido-2-O...

Castanospermine and 3'-azido-3'-deoxythymidine (zidovudine) were evaluated in combination against human immunodeficiency virus (HIV) replication in vitro. Castanospermine and 3'-azido-3'-deoxythymidine inhibited HIV type 1 synergistically in acutely infected H9 cells. In addition, they synergistically inhibited both HIV type 1 and HIV type 2 in peripheral blood mononuclear cells. There were no ...

An azido-avermectin analog [4'' alpha-(4-azidosalicylamido-epsilon-caproylamido-beta-alan ylamido)-4''-deoxyavermectin B1a; azido-AVM] was synthesized and used to photoaffinity label avermectin binding sites present in the membranes of Caenorhabditis elegans and Drosophila melanogaster. Azido-AVM was biologically active and behaved like a competitive inhibitor of [3H]ivermectin binding to C. el...

An analog of ADP containing an azido group at the C-2 position of the purine ring has been synthesized and used as an affinity probe of the membrane-bound coupling factor 1 of spinach chloroplast thylakoid membranes. The 2-azido-ADP inhibited light-induced dark binding of ADP at the tight nucleotide binding site on the thylakoid membranes. The 2-azido-ADP itself bound tightly to the thylakoid m...