Alkali metal ions protect mitochondrial rhodanese against thermal inactivation.
Incubation of bovine liver mitochondrial rhodanese in dilute, reducing solutions at temperatures ranging between 30 and 45 degreesC conduced to a rapid loss of enzymatic activity. This inactivation was substantially reduced in the presence of millimolar concentrations of alkali metal ions, divalent cations (including Mg2+, Ca2+, and Ba2+) were ineffective. The extent of protection afforded by monovalent cations was highly dependent on their ionic radii, with K+ and Na+ ions being the most effective protective agents. The protection afforded by a number of anions, including thiosulfate, could be totally ascribed to the presence of the accompanying monovalent cation. The overall results indicate that K+ and Na+, at concentrations and temperatures within the physiological range, substantially contribute to the stabilization of the functional structure of rhodanese.
Dionisi
H M
HM
Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, Rosario, 2000, Argentina.
Alvarez
C V
CV
Viale
A M
AM
D000818:Animals; D002417:Cattle; D004789:Enzyme Activation / Q000187:drug effects; D004795:Enzyme Stability / Q000187:drug effects; D006358:Hot Temperature; D008672:Metals, Alkali / Q000494:pharmacology*; D008930:Mitochondria, Liver / Q000187:drug effects* / Q000201:enzymology*; D011188:Potassium / Q000494:pharmacology; D012492:Salts / Q000494:pharmacology; D012964:Sodium / Q000494:pharmacology; D013884:Thiosulfate Sulfurtransferase / Q000378:metabolism*; D013885:Thiosulfates / Q000494:pharmacology
D008672:Metals, Alkali; D012492:Salts; D013885:Thiosulfates; D012964:Sodium; D013884:Thiosulfate Sulfurtransferase; C017717:sodium thiosulfate; D011188:Potassium