C. Kiryu et al., Physiological production of singlet molecular oxygen in the myeloperoxidase-H2O2-chloride system, FEBS LETTER, 443(2), 1999, pp. 154-158
The putative role of singlet oxygen (O-1(2)) in the respiratory burst of ne
utrophils has remained elusive due to the lack of reliable means to study i
ts quantitative production. To measure O-1(2) directly from biological or c
hemical reactions in the near infrared region, we have developed a highly s
ensitive detection system which employs two InGaAs/InP pin photodiodes inco
rporated with a dual charge integrating amplifier circuit. Using this detec
tion system, we detected light emission derived from a myeloperoxidase (MPO
)-mediated reaction in physiological conditions: pH 7.4, 1-30 nM MPO, 10-10
0 mu M H2O2 and 100-130 mM Cl- in place of Br- without the use of deuterium
oxide. The MPO-H2O2-Cl- system exhibited a single emission peak at 1.27 mu
m with a spectral distribution identical to that of delta singlet oxygen,
Our results suggest physiological production of O-1(2) in the MPO-H2O2-Cl-
system at an intravacuolar neutral pH. The MPO-mediated generation of O-1(2
), which may have an important role in host defense mechanisms, is discusse
d in connection with previous results. (C) 1999 Federation of European Bioc
hemical Societies.