Protein and nucleic acid metabolism in fruits. I. Studies of amino acid incorporation during the climacteric rise in respiration of the avocado.

Incorporation of (14)C L-valine and (14)C L-leucine into protein of tissue slices of the avocado fruit was relatively high during the early stages of the climacteric rise, declined sharply thereafter, and was virtually absent at the peak. The incorporation of amino acids in the preclimacteric stage was markedly lower than during the early stage of the respiratory rise. By following incorporation in relation to uptake at several concentrations it was established that the results were not a reflection of endogenous dilution. Puromycin was effective as an inhibitor of incorporation but not of oxygen uptake. When respiration was at its maximum there was no protein synthesis. It was concluded, therefore, that the respiratory upsurge characteristic of the climacteric was not related directly to protein synthesis.