Spinach malic” enzyme

Periodate-oxidized NADP has been used as an affinity label for other NADP-specific enzymes including pigeon liver malic enzyme (72, 73), spinach ferre-doxin-NADP reductase (74, 75), and Leuconostoc mesenteroides glucose-6-phosphate dehydrogenase (76). Recently, a new fluorescent dialdehyde derivative has been reported as an affinity label of NADP sites, namely, periodate-oxidized 3-aminopyridine adenine dinucleotide phosphate (77). 

The reaction was carried out with a suspension of chloroplasts from spinach leaves and malic enzyme from a pigeon-liver preparation. The reaction was followed by measuring the production of L-malic acid. In the dark, or in the absence of either the malic enzyme or TPN+, no malic acid was observed. These results were confirmed by both Tolmach 29) and Arnon... 

Ochoa s main contribution in this area was the discovery, with Wolf Vishniac in 1951, that spinach grana have the ability to reduce NAD and NADP under the influence of light. This was the first demonstration of hydrogen fixation by physiological acceptors catalyzed by radiant energy. Leonard Tolmach and Daniel Arnon also obtained similar results. The formation of NADPH was coupled under the influence of light, pyruvic acid and CO2 in the presence of the malic enzyme, with formation of malic acid. Later on, coupling was demonstrated with a variety of purified enzymes. 

The uptake and biotransformation of benzene from soil and the atmosphere has been studied in a nnmber of plants. It was shown that in leaves of spinach Spinacia oleraced) the label in -benzene was fonnd in mnconic, fnmaric, snccinic, malic, and oxalic acids, as well as in specific amino acids, and that an enzyme preparation in the presence of NADH or NADPH prodnced phenol (Ugrekhelidze et al. 1997). 

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