par Ledoux, Lucien 
Référence Biochimica et biophysica acta, 13, page (121-134)
Publication Publié, 1954
Référence Biochimica et biophysica acta, 13, page (121-134)
Publication Publié, 1954
Article révisé par les pairs
| Résumé : | 1. 1. Reduced glutathione, cyanide and sulphite activate ribonuclease. This activation is due to the oxido-reduction properties of these substances. 2. 2. Oxidized glutathione and iodosobenzoic acid inhibit the enzyme. This inhibition is reversible under the action of reducing agents and its rate depends on the pH conditions. 3. 3. Atmospheric oxygen and hydrogen peroxide also inhibit the enzyme. The reaction is catalysed by metallic ions (Cu+2 etc.) and by cyanide. The solutions thus treated are reactivated by the reducing agents (cyanide included) after destruction of the oxidizing agents. 4. 4. The use of redox buffer solutions shows that the activity of ribonuclease is a simple function of oxido-reduction potentials. 5. 5. A structural scheme of the protein is proposed on the basis of its enzymic properties. It implies the presence of two pairs of oxidizable thiol groups of which the normal potentials are evaluated as 0.27 V and 0.64 V. These thiol groups are responsible, or at least partly, for the enzymic activity of the protein. 6. 6. This structural scheme has been confirmed chemically. © 1954. |
