Sources and Mechanisms of Carbon Monoxide Production by Irradiation

The sources and mechanisms of gas production by irradiation were determined using model systems prepared with fatty acid, phospholipids, oil, sugars, glycolysis and TCA cycle intermediates, nucleic acids, amino acid monomers and homopolymers, and proteins. The model systems were irradiated at 0, 2.5, 5, or 10 kGy using a linear accelerator and the amounts of CO, CO 2, and CH4 produced were determined using gas chromatography. The productions of CO, CO2, and CH4 in all samples were irradiation-dose dependent. Glycine, asparagine, and glutamine were the major sources of CO production among amino acids, and glyceraldehydes, pyruvate, and -ketoglutarate were the major sources of CO among glycolysis intermediates. Phosphatidyl choline, phosphatidyl ethanolamine, and lysophosphatidyl choline produced the greatest amounts of CO among the phospholipids. The major sources of CO 2 production were pyruvate, threoine, and methionine, and those of CH4 were methionine and acetone. The amounts of CO produced from these sources were significant, and the production of gas compounds via radiolytic degradation appears to be closely related to the structure of molecules.