[Isolation and study of some properties of new phosphopeptides from nerve tissue]. / Vydelenie i izuchenie nekotorykh svoistv novykh fosfopeptidov nervnoi tkani.

The phosphopeptides were extracted by organic solvents from the lipid-deleted homogenate of rat brain tissue. The latter was obtained by means of trichloroacetic acid from rats injected with 32P-NaH2PO4 into brain ventricles. Chromatography of the brain extract on DEAE-Sephadex A-25 and gel filtration through Sephadex G-25 and G-15 resulted in 3 homogenous fractions of the phosphopeptides characterized by the maximal rate of the label incorporation. These fractions appeared to be homogenous during polyacrylamide gel electrophoresis and thin-layer chromatography. The molecular weights of the fractions are equal to 1200, 1100 and 900, respectively; the isoelectric points lie at 3.2, 3.0 and 3.1, respectively. All the phosphopeptides tested contain large amounts of glycine, serine and glutamic acid and have alanine as N-terminal amino acid.

[Fractionation of brain phosphopeptides]. / Fraktsionirovanie fosfopeptidov golovnogo mozga.

Anion-exchange chromatography was used to fractionate the brain phosphopeptides preparations obtained by the common method and the method modified by the author. The data of a comparative analysis show that in fractions obtained from our preparation the content of amide nitrogen as well as of phosphate residues is higher than in the analogous preparations of Ledig and Mandel. Changes are found in the spectrum of the phosphopeptides fractions isolated during incubation of the brain tissue homogenate under aerobic conditions (1 h; 37 degrees C). It is shown that the amount of phosphopeptide fractions decreases after incubation, and the total content of nitrogen, content of amide nitrogen and phosphorus in eluted fractions undergo redistribution.