The metabolism of chlorotic leaves. 2. Organic acids

Investigations of the Role of Iron in Chlorophyll Metabolism. II. Effect of Iron Deficiency on Chlorophyll Synthesis

“…Recently DeKock (3) and co-workers reported that iron deficiency greatly reduced the aconitase activity of mustard leaves, but they were unable to demonstrate a direct association of iron with the enzyme. The effect of the iron supply on the relative concentrations of citrate and malate is well established (8). The slow rate of incorporation of C14 from citrate, succinate, and a-ketoglutarate into chlorophyll indicates that the isotope probably made one or more turns around the Krebs cycle prior to entering the porphyrin biosynthetic pathway.…”

“…The paper and discs were transferred to a petri dish which contained the radioactive substrate in 3 ml of water. When b-AL-2-C14 was used as the substrate, 8 The leaf pigments were extracted from ten 1-cm discs by grinding the tissue in 30 ml of a mixture of acetone and HCl (28.5 ml acetone and 1.5 ml 0.5 N HCl). The dilute acid converted the chlorophylls to the more stable pheophytin derivatives.…”

“…Also, the sum of NADP and NADPH is greater in organs which have a high degree of synthetic ability than in those organs which have a relatively low synthetic activity and a high energy-dispensing activity (8,10). Moreover, on the basis of data of this kind, several investigators have advanced the hypothesis that the reducing agent in biosynthetic steps in animal tissues is NADPH and the oxidizing agent is NAD (10).…”

“…ties which are inherent in the recoveries (8). But even so, the bulk of the available data indicates that the amount (on a fresh weight basis) of NADPH in animal tissues is much higher than that of NADP so that a high ratio of NADPH/NADP is maintained in most if not all animal tissues, whereas in the same tissues NAD is higher than NADH [see Lowenstein's review (10); also see Caiger et al (3)].…”

Effects of calcium, potassium, & magnesium on oxalic, malic, & citric acid content of valencia orange leaf tissue

“…Several investigations have dealt with the effect of nutrition on organic acids of leaf and fruit tissues (2,3,5,13). In general, the effects of cations on the organic acids in leaf tissue are rather complex.…”