Chlorophyll chelate effect

Chelate cooperative model, 60—61 Chelate cooperativity, 42—43, 51—55, 78 binding of divalent asymmetric ligand, 51 f binding of divalent ligand, 53 factor, 54, 54f—55f Chelate effect, 51—55 Chlorophyll a/b (Chi a/b), 232 Chromophore, 221—222 Cluster, 204—205 COCOC chain, 30-31 Coherences, 230—231 Computational studies of environmental effects... 

Figure 11.13 Effects of the addition of dissolved inorganic N (NELj and NOj , 5 pM each), N-containing rainfall (collected at Morehead City, NC), iron (as EDTA-chelated and non-chelated FeCla 0.2 pM each EDTA, and the combination of NOs and EDTA-chelated FeCls) on coastal Atlantic Ocean phytoplankton communities. In situ bioassays were conducted for 5 days on seawater collected approximately 25 km SE of Beaufort, NC in the summer of 1994. Phytoplankton growth responses are reported as photosynthetic CO2 fixation and chlorophyll a accumulation. Indicates treatments were significantly (p < 0.05) from controls, using Bonferroni a posteriori comparisons of the means. See Paerl etal. (1999) for details of the experimental procedures.

However, wheat protoplasts have no other demonstrable responses to cytokinin and, therefore, the lack of a cytokinin effect on calcium transport is not a decisive test. Zhao and Ross [69] used zeatin induced growth and chlorophyll formation in excised cucumber cotyledons as cytokinin responses to examine the effects of calcium chelators, ionophore and several anti-calmodulin drugs. None of these drugs affected the two cytokinin responses unless used at concentrations high enough to cause indirect damage. 

A new approach recently was taken to maintain an excess of soluble scavenging metal in a mud and to minimize the adverse effects of the metal ion. The metal ion is bonded loosely with an organic compound (ligand) that is highly water-soluble. These organometallic compounds are commonly called metal chelates. Examples are hemoglobin in blood (iron chelate) and plant chlorophyll (magnesium chelate). 

After a dark pretreatment with ALA or metal chelators etiolated cress plants show an increase of pchl(ide) synthesis under our experimental conditions to 214% (ALA), 119% (Phe), 146% (2 2) and 136% (8H) of the water control (Fig.2). The chlorophyll content of ALA-fed seedlings is found to be diminished (80% chi a, 43% chi b of water control) after exposure to white light for 12h. A similar, but stronger effect can be seen after incubation with metal chelators (Fig.l). The reduced rate of greening concerns chi b to the same extent as chi a, but not carotenoids (see Table I). 

The effect of chelators in the light is known to inhibit chlorophyll synthesis (5). We corroborate and extent the observation of (9) that one possible site of inhibition of chlorophyll synthesis is the esterification of chlide. We do not agree, however, with (9) that chloro-phyllase is the attacked enzyme. According to (11), chlorophyll synthetase is responsible for phytylation of chlide. Here we report the first evidence that esterification of chlide is a real target of metal chelator action. 

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