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—The two enzymes methylating myelin basic protein and histone were purified 170‐ and 250‐fold respectively from the cell sap fraction of rat brain. These enzymes methylated only arginine residues of the two proteins. The enzyme activities were present in all organs tested. Testis has the highest, brain a moderate and liver the lowest activity. Most of the activities were present in the cell sap fraction in brain, liver and testis. Methylation of myelin basic protein and histone was examined in both the cell sap and solubilized nuclear fraction of rat brain during life span after birth. The myelin basic protein methylating activity in the cell sap fraction increased during myelination. Histone methylase from the nuclear fraction was highest at birth and dropped rapidly thereafter. The other activities remained unchanged. The natural occurrence of NG‐mono‐ and NG,NG‐dimethylarginine residues in histones prepared from rabbit liver was demonstrated.

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An extracellular cytolysin produced by Vibrio metschnikovii was purified by acid precipitation, phenyl-Sepharose CL-4B chromatography, and rechromatography on a phenyl-Sepharose CL-4B column and high-performance liquid chromatography on a Mono Q (anion-exchange) column. The purified cytolysin had a molecular weight of 50,000 and an isoelectric point of 5.1. It was inactivated by heating at 60°C for 5 min and was inhibited by Zn2+, Cu2+, and high concentrations of cholesterol. Lysis of calf erythrocytes by cytolysin was temperature dependent and occurred only above 18°C. Moreover, no lysis was observed at high concentrations of erythrocytes, suggesting that the cytolysin lyses erythrocytes by a multihit mechanism. This cytolysin had no immunological cross-reactivities with hemolysins from other Vibrio species tested, indicating that it is a new cytolysin. V. metschnikovii cytolysin lysed erythrocytes from several animal species (calf, rabbit, guinea pig, mouse, human, sheep, chicken, and horse) and cultured cells (Vero and Chinese hamster ovary), caused fluid accumulation in the intestines of infant mice, and increased vascular permeability in rabbit skin.