Multiple forms of phosphoprotein phosphatase and its protein inhibitors from rat brain.

By means of Sephadex A-50 ion exchange chromatography 5 peaks of phosphoprotein phosphatase (PPase) activity have been detected in rat brain. These molecular forms of the enzyme differ from each other by their specific activity as well as by a number of other properties--pH optima, heat and storage stability, and substrate specificity. It was shown that cyclic AMP (10(-5)-10(-6) M) decreased PPase activity of the majority of the peaks (I-III, V) and increased that of the peak IV. Ion exchange chromatography of brain tissue extracts revealed 4 peaks of PPase protein inhibitors. The results obtained on dialysis and tryptic digestion point to the protein nature of the inhibitors that differed from each other by their effect on the enzyme activity and heat stability (95 degrees C, 5 min). The significance of the specificity of separate molecular forms of PPases is discussed.

Two copper-containing proteins from white and gray matter of brain.

The procedure for the isolation of two water soluble copper-containing proteins from the white and gray matter of bovine brain is described. One of the proteins, cerebrocuprein I, is superoxide dismutase; and three molecular forms of this enzyme are to be found in brain. The other protein present in gray and white matter is devoid of superoxide dismutase and amine oxidase activities. The amino acid composition, molecular weight, isoelectric point and copper content of this protein were determined. The effect of some agents, pH and thermal treatment of the optical and EPR spectra of the protein were also studied. The copper of the protein may be removed and the holoprotein reconstituted again from apoprotein and copper. The results obtained led to the conclusion that in brain a new copper protein is discovered, which is named neurocuprein.