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Physiological production of singlet molecular oxygen in the myeloperoxidase‐H 2 O 2 ‐chloride system
Author(s) -
Kiryu Chika,
Makiuchi Masao,
Miyazaki Junji,
Fujinaga Toru,
Kakinuma Katsuko
Publication year - 1999
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)01700-1
Subject(s) - singlet oxygen , myeloperoxidase , chemistry , oxygen , photochemistry , respiratory burst , chloride , analytical chemistry (journal) , biochemistry , organic chemistry , biology , immunology , inflammation
The putative role of singlet oxygen ( 1 O 2 ) in the respiratory burst of neutrophils has remained elusive due to the lack of reliable means to study its quantitative production. To measure 1 O 2 directly from biological or chemical reactions in the near infrared region, we have developed a highly sensitive detection system which employs two InGaAs/InP pin photodiodes incorporated with a dual charge integrating amplifier circuit. Using this detection system, we detected light emission derived from a myeloperoxidase (MPO)‐mediated reaction in physiological conditions: pH 7.4, 1–30 nM MPO, 10–100 μM H 2 O 2 and 100–130 mM Cl − in place of Br − without the use of deuterium oxide. The MPO‐H 2 O 2 ‐Cl − system exhibited a single emission peak at 1.27 μm with a spectral distribution identical to that of delta singlet oxygen. Our results suggest physiological production of 1 O 2 in the MPO‐H 2 O 2 ‐Cl − system at an intravacuolar neutral pH. The MPO‐mediated generation of 1 O 2 , which may have an important role in host defense mechanisms, is discussed in connection with previous results.