Metal Ion Catalysis of the Decarboxylation of Oxalo-Acetic Acid

Nature ◽  
1953 ◽  
Vol 171 (4346) ◽  
pp. 304-305 ◽  
Author(s):  
R. J. P. WILLIAMS
Keyword(s):  
Acetic Acid ◽  
Metal Ion ◽  
Metal Ion Catalysis

scholarly journals Studies of the limited degradation of mucus glycoproteins. The mechanism of the peroxide reaction

1985 ◽  
Vol 228 (3) ◽  
pp. 615-626 ◽  
Author(s):  
B Cooper ◽  
J M Creeth ◽  
A S Donald
Keyword(s):  
Superoxide Dismutase ◽  
Acetic Acid ◽  
Metal Ion ◽  
Histidine Residues ◽  
Essential Step ◽  
Oxidation Reduction ◽  
Reduction Cycle ◽  
Metal Ion Catalysis ◽  
Chelex Resin ◽  
Mucus Glycoproteins

The reaction between ovarian-cyst glycoproteins and H2O2 was investigated in the presence of a number of inhibitors and catalysts. Azide and 2H2O were separately found to have little effect, implying that singlet oxygen was not involved. Superoxide dismutase was destroyed by H2O2, but mannitol had no effect: thus generalized attack by OH., whether originating from HO2.- or more directly, is not indicated. The glycoproteins contained trace quantities of Cu and Fe, amounting to about 2 atoms of metal per glycoprotein molecule. Treatment of the glycoproteins with the strong chelator DETAPAC (diethylenetriaminepenta-acetic acid) or Chelex resin eliminated the reaction with H2O2; activity could be restored by addition of Cu2+ or Fe2+ in millimolar quantities. It was concluded that metal-ion catalysis is an essential step in the attack of H2O2 on glycoproteins. Spectroscopic and other evidence showed that Cu2+ (and probably Fe2+) complexes strongly with poly-L-histidine, and implies that the Cu2+ or Fe2+ in the glycoproteins is complexed with some of the histidine residues in the glycosylated backbone. Neither polyhistidine nor polyproline reacted with H2O2 in the absence of metal ions, but small quantities of Cu2+ or Fe3+ caused degradation. This was rapid with polyhistidine, which was converted largely into aspartic acid, but slower with polyproline, where limited conversion into glutamic acid occurs. These findings confirm the original hypothesis that peroxide attack on glycoproteins occurs largely at the histidine residues, with simultaneous peptidolysis. The mechanism most probably involves the liberation of OH. by an oxidation-reduction cycle involving, e.g. Cu+/Cu2+: specificity of attack at histidine is due to the location of the metal at these residues only.

Metal Ion Catalysis in the Hydrolysis of Potassium Ethyl Oxalate

Nature ◽  
1964 ◽  
Vol 204 (4964) ◽  
pp. 1189-1190
Author(s):  
ROBERT W. HAY ◽  
NEIL J. WALKER
Keyword(s):  
Metal Ion ◽  
Metal Ion Catalysis ◽  
Hydrolysis Of

Metal-ion catalysis of ethyl oxalate hydrolysis

1971 ◽  
Vol 93 (5) ◽  
pp. 1106-1110 ◽  
Author(s):  
Gordon Lee Johnson ◽  
Robert J. Angelici
Keyword(s):  
Metal Ion ◽  
Metal Ion Catalysis

Template-Directed Synthesis of Oligoguanylic Acids- Metal Ion Catalysis

1981 ◽  
pp. 233-239 ◽  
Author(s):  
P. K. Bridson ◽  
H. Fakhrai ◽  
R. Lohrmann ◽  
L. E. Orgel ◽  
M. van Roode
Keyword(s):  
Metal Ion ◽  
Directed Synthesis ◽  
Metal Ion Catalysis
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