Tissue distribution of mammalian sulfhydryl oxidase

Sulfhydryl oxidase activity is present in cow, goat, sow, human, and rat milks, and can also be measured in several rat tissues following homogenization in 1% polyoxyethylene-9-lauryl ether. These include lactating mammary tissue, kidney, and pancreas. Bovine kidney homogenates also exhibit sulfhydryl oxidase activity; however, no activity could be detected in rat thymus, brain, heart, liver, spleen, lung, or small intestinal tissue homogenates. Indirect immunofluorescent staining of tissue sections using rabbit antibodies directed against highly purified bovine milk sulfhydryl oxidase preparations revealed that the enzyme is closely associated with the plasma membrane of lactating cow and rat mammary tissues and the basal-lateral membrane of rat kidney cortex. In addition, the oxidase appears to be associated with endothelial cells lining the capillaries of rat kidney, heart, and small intestine, and centroacinar cells in pancreatic tissue slices also stain for sulfhydryl oxidase. In contrast, liver, brain, and thymus tissues do not exhibit fluorescent staining and appear to be devoid of sulfhydryl oxidase activity.