Chloroperoxidase generation of singlet Delta molecular oxygen observed directly by spectroscopy in the 1- to 1.6-mum region.

The (0,0) (1)Delta(g) --> (3)Sigma(-) (g) singlet molecular oxygen chemiluminescence emission from a biological reaction system, chloroperoxidase (EC 1.11.1.10) acting on hydrogen peroxide at low pH (phosphate buffer, pH 2.85) with Cl(-) as a cosubstrate, was recorded with an ultrasensitive IR spectrometer. The strong chemiluminescence emission peak observed at 1.30 mum provides clear evidence of the enzymatic generation of (excited) singlet oxygen from peroxide in this system.