A Co(III) derivative of concanavalin A.
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Binding Sites↗
Biomedical subjects
J I Legg
Publications and source records attributed to J I Legg.
A peptidase-inactive derivative of carboxypeptidase A modified specifically at tyrosine 248. Cobalt(III) (ethylenediamine-N,N'-diacetato) (arsanilazotyrosinato 248 carboxypeptidase A).
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Animals↗
Inactivation of myosin subfragment one by cobalt(II)/cobalt(III) phenanthroline complexes. I. Incorporation of Co(III) by in situ oxidation of Co(II).
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Adenosine Triphosphatases↗
Development of a method for the incorporation of substitution-inert metal ions into proteins. Site-specific modification of arsanilazotyrosine-248 carboxypeptidase A with cobalt(III).
This investigation demonstrates the use of substitution-inert metal ions as site-specific amino acid modifying reagents. The approach involves the production of a chelating agent at the site of interest with the subsequent in situ oxidation of substitution-labile cobalt(II) to exchange-inert cobalt(III) with H2O2. We have produced the chelate complex ethylenediamine-N,N'-diacetato(arsanilazotyrosinato-248 carboxypeptidase A)cobalt(III) [CoIII(EDDA)(AA-CPA-Zn)]. Model CoIII(EDDA)(azophenolate) complexes have helped to define the reaction conditions necessary to produce the enzyme derivative and have proved invaluable in the spectral analysis of the cobalt(III)-enzyme complex. The modified enzyme contains one active-site zinc and one externally bound cobalt per enzyme monometer. Circular dichroism and visible spectra of the derivative and apoenzyme substantiate the site-specific nature of the incorporation. Concimitant with CoIIIEDDA incorporation, the enzyme loses its peptidase activity yet maintains with FeIIEDTA returns the original properties of the arsanilazotyrosine-248 enzyme.
Amino Acids↗
The importance of side chain intramolecular interaction on the stereochemical course of the 2-carbon deuteration of amino acids complexed to cobalt(III).
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Amino Acids↗
Five-coordinate amino acid complexes. Synthesis and characterization of nickel(II), copper(II), and zinc(II) complexes of 1,5-diazacyclooctane-N-monoacetic acid.
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Acetates↗
Synthesis and isolation of optically pure L- and D-2-2H amino acids via cobalt(III) chelates.
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Amino Acids↗
Cobalt(III) complexes of bidentate azotyrosine analogs.
As analogs for cobalt(III) complexes of bidentate azotyrosine in proteins, several cobalt(III) complexes of bidentate azophenols have been prepared and characterized. Tris(2-phenylazo-p-cresolato)cobalt(III) was shown to be a poor model complex for this purpose; while cobalt(III) complexes of either 2-phenylazo-p-cresol or 2-(4-carboxyphenylazo)-4,5-dimethylphenol with the linear tetradentate ligand ethylenediamine-N,N'-diacetic acid are very useful as model complexes. The complexes were characterized by magnetic susceptibility, visible spectra and 1H NMR. In the case of one of the mixed ligand complexes, a detailed description of the stereochemistry was possible. Comparisons of the spectral characteristics of metal complexes with bidentate and tridentate azophenols are made. These model studies are essential to a program involving the site specific modification of proteins with substitution inert metal ions.
Azo Compounds↗
Exchange-inert metal ions as probes of enzyme structure-function relationships. Cobalt(III), cobalt(II), and zinc(II), azophenol complexes as models for enzyme azotyrosine complexes.
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Azo Compounds↗