Testing the protein error theory of ageing: a reply to Baird, Samis, Massie and Zimmerman.

A major prediction of Orgel's theory is that the misincorporation of amino acids into proteins will increase with age. This has not yet been tested experimentally. Indirect methods have been used to search for the presence of altered proteins in ageing cells or organisms, but these would not necessarily detect a low level of mistakes, nor do they distinquish between errors in synthesis and post-synthetic changes. Nevertheless, some experimental results have been obtained from genetic and biochemical studies with fungi and fibroblasts which confirm certain predictions of the protein error theory.