ASPECTS OF AMINO-ACID-METABOLISM IN STORED POTATO-TUBERS (CV PENTLANDDELL)

Tubers of the cv. Pentland Dell were stored at 5 and 10 degrees C for up to 33 weeks and analysed for soluble protein and free amino acids. In addition, glutamine synthetase, NADH-GOGAT and acid proteinase acti vities were measured over the 33-week storage period. An accumulation of asparagine and glutamine occurred during late storage which coincid ed with an upturn in proteinase activity. The amide content of the maj or tuber storage proteins suggested that amidation of free amino acids must account for the high proportion of free amides. The activities o f glutamine synthetase and NADH-GOGAT further indicated amidation of f ree amino acids throughout storage, independent of storage temperature , An increase of total soluble protein during storage suggested that m uch of the observed increase in amides resulted from translocation int o the tuber core tissue, perhaps as a result of the chemical suppressi on of sprout growth. (C) 1997 Elsevier Science Ireland Ltd.