A simple reproducible cell-free system for measuring brain protein synthesis.

A simple, rapid, sensitive, and reproducible cell-free assay system for studying brain protein synthesis is described. This system uses small amounts of brain postmitochondrial supernatant, making it a convenient screening test when only small amounts of tissue are available. It showed over 95% dependence on Mg2+ and on an energy source. Optimal incorporation occurred under the following conditions: Mg2+ 3 mM; ATP, 0.6 mM; GTP, 0.6 mM; high K+, greater than or equal to 25 mM; Low Na+, less than or equal to 15 mM; pH 7.1-7.5. The rate of amino acid incorporation did not vary with leucine concentrations in vitro up to 1 mM, which obviated the need to measure endogenous leucine concentrations.