Physiological production of singlet molecular oxygen in the myeloperoxidase‐H₂O₂‐chloride system

Abstract

The putative role of singlet oxygen ( I O P ) in the respiratory burst of neutrophils has remained elusive due to the lack of reliable means to study its quantitative production. To measure I O P 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 W WM H P O P and 100^130 mM Cl 3 in place of Br 3 without the use of deuterium oxide. The MPO-H P O P -Cl 3 system exhibited a single emission peak at 1.27 W Wm with a spectral distribution identical to that of delta singlet oxygen. Our results suggest physiological production of I O P in the MPO-H P O P -Cl 3 system at an intravacuolar neutral pH. The MPO-mediated generation of I O P , which may have an important role in host defense mechanisms, is discussed in connection with previous results.z 1999 Federation of European Biochemical Societies.

Chemical Structure-Dependent Differential Effects of Flavonoids on the Catalase Activity as Evaluated by a Chemiluminescent Method

“…The H 2 O 2 -dependent CL emission is indeed controlled by two-electron oxidation of the luminol/NaClO system 13,[18][19][20][21][22] and is not influenced by other mechanisms such as those involving catalase and other peroxidases. 19,23) Because the myeloperoxidase (MPO)-mediated generation of 1 O 2 was suggested in the MPO/H 2 O 2 system through the generation of HClO by MPO, 24,25) the generation of 1 O 2 was evaluated in our system, using CLA in place of luminol. Addition of NaClO to a mixture of CLA, DTPA, and H 2 O 2 resulted in the weak luminescence less than 20 kilocpm (data not shown), indicating that 1 O 2 is a minor species in this system.…”

In Vitro and In Vivo Activities of E-101 Solution against Acinetobacter baumannii Isolates from U.S. Military Personnel

“…The enzymatic activity of GO directed to glucose results in production of hydrogen peroxide (H 2 O 2 ) (serving as a substrate for catalysis of pMPO), oxidation of chloride to hypochlorous acid (HOCl), and production of H 2 O 2 for a reaction with HOCl to produce singlet oxygen ( 1 O 2 ). The antimicrobial mechanism of action of E-101 solution is enhanced by the binding of pMPO to the surface of target microorganisms, thereby optimizing direct oxidative damage of microbes by focused production of HOCl, which reacts with an additional H 2 O 2 , producing 1 O 2 (1,2,5,10,11,17,20). Singlet oxygen is a potent antimicrobial product of the myeloperoxidase system, but the short lifetime of 1 O 2 (about 2 s in water) restricts its kill radius to the width of the bacterial cell wall, thus precluding collateral damage to surrounding host cells and tissue (1,2,3,13,14,18).…”

Inhibition of glyceraldehyde-3-phosphate dehydrogenase by peptide and protein peroxides generated by singlet oxygen attack

“…1 O 2 generation has been reported in myeloperoxidase-and eosinophil peroxidase-catalysed reactions [1][2][3], and by some activated cell types including neutrophils [4], eosinophils [3,5], and macrophages [6]. As a result of the widespread exposure of humans to UV and visible light, 1 O 2 has been suggested to play a key role in the development of a number of human pathologies including cataract, sunburn, some skin cancers and aging [7][8][9][10][11][12].…”