Radiation-induced enhancement of nitrite reducing activity of cytochrome c.
Commercial cytochrome c (Cyt c) was irradiated with Co-60 gamma-rays in the dose range of up to 3.0 kGy to investigate the enhancement of the nitrite reducing activity of Cyt c. The optimum irradiation dose to induce nitrite reducing activity for 30 muM Cyt c solution was 1.0 kGy under an O(2) atmosphere. The nitrite reducing activity of Cyt c irradiated at this dose was approximately 45-fold that of unirradiated Cyt c and ca. 1.2-fold that of nitrite reductase. The irradiation treatment resulted in unfolding of the peptide chain, exposure of the heme group, oxidation of methionine to methionine sulfoxide, dissociation of the sixth ligand (Met), and occurrence of autoxidation in Cyt c. Sepharose-immobilized irradiated Cyt c had a similar activity to that in solution. The resin retained the activity after five uses even after 1 year of storage. The irradiated Cyt c will be able to be used as a substitute for nitrite reductase.
Suruga
Kohei
K
Department of Biological Chemistry, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, Kanagawa 252-8510, Japan.
Nagasawa
Naotsugu
N
Yamada
Seiji
S
Satoh
Tadashi
T
Kawachi
Ryu
R
Nishio
Toshiyuki
T
Kume
Tamikazu
T
Oku
Tadatake
T
D002942:Circular Dichroism; D045304:Cytochromes c / Q000737:chemistry* / Q000528:radiation effects*; D004355:Drug Stability; D005720:Gamma Rays; D006418:Heme / Q000737:chemistry; D008715:Methionine / Q000737:chemistry; D009572:Nitrite Reductases / Q000378:metabolism; D009573:Nitrites / Q000737:chemistry*; D010084:Oxidation-Reduction; D017510:Protein Folding
D009573:Nitrites; D006418:Heme; D045304:Cytochromes c; D008715:Methionine; D009572:Nitrite Reductases