Polyamine effects on 14C-leucine transfer to microsomal protein in a rat liver cell free system during ageing

Abstract

The in-vitro incorporation of 14C-leucine into liver microsomal protein from 14C-leu- tRNA has been studied in 3–6 and 22–24-month-old rats using a cell free system with lysosome-free microsomes (rough E.R.), limiting transfer factor and GTP concentrations and an energy generating system. The amino acid incorporating ability by old microsomes slightly decreases when they are incubated with their “homologous” cell sap transfer factors. A more marked decrease occurs when they are incubated with the “heterologous” young cell sap factors. Young microsomes also show a decrease in their incorporating ability when they are incubated with the old cell sap. The polyamines spermine and spermidine reverse these inhibitions. Spermine acts with the old microsomal preparations and spermidine, on the contrary, with the young ones. Spermine when used with young microsomes and spermidine with the old preparations are both inhibitory. Same 14C-leucine accepting abilities are shown by tRNA preparations from young-adult as well senescent animals.