In an experiment, metabolically active cells are subjected to radiant energy in the form of x-rays. This results in cell injury caused by hydrolysis of water. Which of the following intracellular enzymes helps to protect the cells from this type of injury?

The body has intracellular mechanisms that prevent damage from free radicals generated by exposure to x-rays. Glutathione peroxidase reduces such injury by catalyzing the breakdown of hydrogen peroxide. Endonucleases damage DNA in nuclear chromatin. Lactate dehydrogenase is present in a variety of cells, and its elevation in the serum is an indicator of cell injury and death. Phospholipases decrease cellular phospholipids and promote cell membrane injury. Proteases can damage cell membranes and cytoskeletal proteins.