Jun Zeng1, Qiyin Sun2, Jihui Su3, Jihui Han3, Quanshi Zhang2, Yuehui Jin4. 1. Beijing Big Base (Top Grade) Equipment Co., LTD China ; Wuxi Yiren Cancer Hospital China. 2. Beijing Big Base (Top Grade) Equipment Co., LTD China. 3. Foundation Lab, Wuxi Yiren Cancer Hospital China. 4. Radiation Therapy Center, Wuxi Yiren Cancer Hospital China.
Abstract
AIM: To study the role of protoporphyrin IX (pPIX) in mitochondrial metabolism of hydrogen peroxide (H2O2). METHODS: O2 (-) specific fluorescent markers DMA (9,10-dimerthylanthracence) and SOSG (Singlet Oxygen Sensor Green reagent) were used for measurement of singlet oxygen ((1)O2). Catalyzing conversion of H2O2 into (1)O2 by pPIX was monitored in vitro under varied H2O2 content, temperature, and PH value in the reaction. Ex vivo mitochondrial model was used to analyze effects of ferrochelatase (FECH) and high energy X-rays on this catalytic reaction. RESULTS: In complete dark, measurable (1)O2 was generated when 1.5 mM of H2O2 was incubated with 24 μM of pPIX H2O2 at 37°C for 3 hours. Mitochondrial yield of H2O2 was 0.11±0.03 nmole/mg/min. Mitochondrial FECH significantly improve the catalytic ability of pPIX converting H2O2 into (1)O2. At presence of high-energy X-ray, incubation of 14.4 μM of pPIX with 0.54 μM of H2O2 also generated (1)O2, during which the fluorescence density of 1.05 μM of DMA decreased by 41.5% (P < 0.05). This conversion was not observed when pPIX was replaced with structurally similar hematoporphyrin. CONCLUSION: pPIX can catalyze conversion of H2O2 into (1)O2.
AIM: To study the role of protoporphyrin IX (pPIX) in mitochondrial metabolism of hydrogen peroxide (H2O2). METHODS:O2 (-) specific fluorescent markers DMA (9,10-dimerthylanthracence) and SOSG (Singlet Oxygen Sensor Green reagent) were used for measurement of singlet oxygen ((1)O2). Catalyzing conversion of H2O2 into (1)O2 by pPIX was monitored in vitro under varied H2O2 content, temperature, and PH value in the reaction. Ex vivo mitochondrial model was used to analyze effects of ferrochelatase (FECH) and high energy X-rays on this catalytic reaction. RESULTS: In complete dark, measurable (1)O2 was generated when 1.5 mM of H2O2 was incubated with 24 μM of pPIXH2O2 at 37°C for 3 hours. Mitochondrial yield of H2O2 was 0.11±0.03 nmole/mg/min. Mitochondrial FECH significantly improve the catalytic ability of pPIX converting H2O2 into (1)O2. At presence of high-energy X-ray, incubation of 14.4 μM of pPIX with 0.54 μM of H2O2 also generated (1)O2, during which the fluorescence density of 1.05 μM of DMA decreased by 41.5% (P < 0.05). This conversion was not observed when pPIX was replaced with structurally similar hematoporphyrin. CONCLUSION:pPIX can catalyze conversion of H2O2 into (1)O2.
Entities:
Keywords:
Protoporphyrin; catalysis; singlet oxygen
Authors: Jon J Ramsey; Kevork Hagopian; Teresa M Kenny; Edward K Koomson; Lisa Bevilacqua; Richard Weindruch; Mary-Ellen Harper Journal: Am J Physiol Endocrinol Metab Date: 2004-01 Impact factor: 4.310