title: Arginase, an S-phase enzyme in a human cell line.
abstract: Suspension cultures of 'Chang liver' cells were synchronized by preincubation in a glutamine-deficient medium or by thymidine blockade. Specific arginase activity varied in the synchronized cultures, being high when the number of S-phase cells was maximal. A relationship between high arginase activity and a high percentage of (S + G2) cells was also found when unsynchronized cells were separated by velocity sedimentation. The increase in arginase activity near the G2/S border was totally inhibited in the presence of cycloheximide. The rate of decrease in activity after addition of the drug indicated that the variations in arginase activity during the mitotic cycle were the result of variations in the rate of synthesis of the enzyme, while the rate of degradation was more or less constant, corresponding to 4--6% per h. The role of arginase in cells lacking a urea cycle and the regulation of arginase activity in 'Chang liver' cells is discussed.
mesh_terms: D001119:Arginase / Q000096:biosynthesis / Q000378:metabolism*; D002453:Cell Cycle; D002460:Cell Line; D003513:Cycloheximide / Q000494:pharmacology; D004261:DNA Replication; D005973:Glutamine / Q000502:physiology; D006801:Humans; D007399:Interphase; D008099:Liver; D013936:Thymidine / Q000502:physiology; D014508:Urea / Q000378:metabolism
chemical_list: D005973:Glutamine; D014508:Urea; D003513:Cycloheximide; D001119:Arginase; D013936:Thymidine