Co-Authors:
Perl, M., Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel
Abstract:
Cell-tree extracts from seeds of onion (Allium cepa), peas (Pisum sativum) and lettuce (Lactuca sativa) exhibit ATP synthesis in the presence of phosphoenolpyruvate (PEP) and AMP. The activity is stimulated by low amounts of ADP or ATP. Reduced NAD replaced AMP in some seeds, and increased the rate of ATP synthesis in the presence of AMP in others. If ADP and PEP were used as substrates (pyruvate kinase), a 5- to 50- times faster ATP synthesis was observed. Examination of enzymes from pea and onion seed extracts revealed that three different enzymes are involved in the conversion of AMP to ATP: (a) pyruvate kinase (EC 2.7.1.40), (b) adenylate kinase (EC 2.7.4.3) and (c) an activity which results in formation of ADP from reduced NAD. The overall activity for ATP synthesis from AMP is stimulated by K+, Mg2+, Mn2+and Co+, and is inhibited by Na+and Ca2+. A scheme for the possible pathway of ATP synthesis in seeds at the early stage of germination is presented. © 1980 Taylor and Francis Group, LLC.