Selective decrease of duodenal phosphoprotein phosphatase activity is a general property of duodenal ulcerogens.

A phosphoprotein phosphatase (PPPase) is inhibited in rat duodenal mucosal cells very early after a single s. c. injection of the duodenal ulcerogens cysteamine, propionitrile and mepirizole.

The influence of cysteamine and propionitrile on duodenal phosphoprotein phosphatase in rats.

Cysteamine and propionitrile cause severe duodenal ulcers with perforation within 24-48 h after a single injection in rats. These animal models were used to gain insight into the early, preulcerogenic biochemical changes in the duodenal mucosa. The results indicate that a single sc injection of cysteamine and propionitrile induced dose- and time-dependent decreases in the activity of phosphoprotein phosphatase (PPPase) in homogenate and particulate fractions of rat duodenal mucosa.

Cobalt-dependent protein phosphatases from human cord blood erythrocytes. II. Further characterization of E2 casein phosphatase.

Of three casein phosphatases isolated from the cytosol of human cord blood erythrocytes two were cobalt-dependent, E2 and E3. In the presence of CoCl2, E2 activity was the most prominent. In addition to casein, E2 dephosphorylated phosvitin and p-nitrophenyl phosphate (p-NPP) with pH optima at 6.

Cobalt-dependent protein phosphatases from human cord blood erythrocytes. I. Submolecular structure and regulation of activity of E3 casein phosphatase.

We have identified three phosphoprotein phosphatases in the cytosol of human cord blood erythrocytes by sequential anion-exchange chromatography and gel filtration. The most abundant was E3 protein phosphatase. After rechromatography on a column of Ultrogel AcA-44 the enzyme had a molecular weight of 95,000 daltons.