|
KMID : 0578319970070040553
|
|
Molecules and Cells
1997 Volume.7 No. 4 p.553 ~ p.558
|
|
|
Fragmentation of Human Cu,Zn-Superoxide Dismutase by Peroxidative Reaction
|
|
Kang Jung-hoon
Kim Sung-Moon
|
|
|
Abstract
|
|
|
We investigated the fragmentation of human Cu,Zn-superoxide dismutase (SOD) by H₂O₂. When Cu,Zn-SOD was incubated with H₂O₂, the fragmentation of protein proceeded rapidly within 1 min. The amounts of OH radical formed in the Cu, Zn-SOD/H₂O₂system reached a maximum in about 3 min. This result suggested that ·OH was implicated in the fragmentation step. Copper ions released from Cu,Zn-SOD were gradually increased up to 30 min after starting the incubation with H₂O₂in a time-dependent manner. However, the fragmentation was not inhibited by 5mM DTPA. The results suggested that the fragmentation of Cu,Zn-SOD by H₂O₂was due to the peroxidative reaction of SOD rather than the Fenton-like reaction by free copper released from oxidatively damaged SOD. A radical scavenger, azide anion, inhibited the fragmentation of Cu,Zn-SOD and the formation of ·OH whereas ethanol did not. These results indicated that azide anions had easy access inside the active channel of Cu,Zn-SOD and thus protected the damage of the
enzyme by ·OH radicals whereas neutral alcohols stayed outside the active channel and could hardly intercept the newly-formed ·OH radicals. Thus we conclude that the fragmentation of Cu,Zn-SOD by H₂O₂is due to the oxidative damage resulting from free ·OH radicals generated by the peroxidative reaction of SOD.
|
|
|
KEYWORD
|
|
|
|
|
|
FullTexts / Linksout information
|
|
|
|
|
|
Listed journal information
|
|
  
|
|