Methyl chlorophyllides

Pheophorblde. Replacement of the magnesium atom In chlorophyllide with hydrogen Ions results In the formation of olive-brown pheophorblde. The degradation of chlorophyllide a and b and their respective methyl and ethyl esters In acidified acetone was studied by Schanderl et al. (10). Substitution of lower molecular weight alcohols decreased sterlc hindrance from the C-7 side chain and Increased reaction rates. Ethyl-chlorophyllide a, methyl-chlorophyllide a, and chlorophyllide reaction 1.08, 1.42, and 1.56 times faster than chlorophyll a at 55°C. The t> derivatives of all chlorophyllldes reacted approximately 5 times slower at the same temperature. Dependence of reaction rate on temperature Is nearly unaffected by length of the C-7 side chain with activation energies of 10.4, 10.6, and 10.8 Kcals/mole reported between 25°C and 55 C, respectively for the 3 reactions. 

Class, G. L., J. J. Katz, F. C. Pennington, M. R. Thomas, and H. H. Strain Nuclear Magnetic Resonance Spectra and Molecular Association of Chlorophylls a and h. Methyl Chlorophyllides, Pheophytins, and Methyl Pheophorbides. 

DiEtMeBPheod 4,5-diethyl methylbacteriopheophorbide d mesoporphyrin IX dimethyl ester Methyl Pheophorbide a Ethyl Chlorophyllide a or b Methyl Chlorophyllide a Methyl Pyrochlorophyllide a 3-vinyl-8-(E-2-nitrovinyl-l)deutero monoanion of 21-Methyl-5,10,15,20-tetraphenylporphyrin monoanion of 21-Phenyl-5,10,15,20-tetraphenylporphyrin dianion of 5,15-dimethyl-2,3,7,8,12,13,17,18-octaethylporphyrin... 

Gloss, G.L. et al.. Nuclear magnetic resonance spectra and molecular association of chlorophylls a and b, methyl chlorophyllides, pheophytins and methylpheophorhides, J. Am. Chem. Soc., 85, 3809, 1963. 

The NCCs detected in extracts from senescent leaves of vascular plants were all found (with one exception (36), see Section 2.2.4) to have a 7-methyl group, as is present in Chi a (la). The fate of the b-type Chls in Chl-breakdown was, therefore, a matter of particular interest (3). The absence of catabolites derived from Chi b (lb) was puzzling, at first. The finding of a biochemical pathway from the b-type to the a-type chlorophyll(ide)s helped to rationalize it (15, 37, 38, 39) chlorophyllide b (3b) is transformed to chlorophyllide a (3a) by reduction of the 7-formyl group of 3b to a 7-methyl group (as in 3a) in a sequence involving two enzymes (15). 

Chlorophyll b, the other chlorophyll present in all green plant tissues, is formed from chlorophyllide b by esterification, as with chlorophyllide a, with geranilgeraniol and followed by three successive hydrogenations to give phytol. Chlorophyllide b is formed from chlorophyllide a by oxidation of the C-7 methyl group to an aldehyde. 

In the first steps of the last section of chlorophyll biosynthesis magnesium is enzymatically introduced into protoporphyrin IX (26) followed by esterification of the 13-propionic acid residue by Mg-protoporphyrin-O-methyl transferase with SAM as a cofactor. At which point the 8-vinyl group is reduced is still unknown. The formed Mg-porphyrin (66) undergoes ring closure with the 17-propionic acid to give protochlorophyllide (67) with the typical isocyclic ring E of chlorophylls. The porphyrin macrocycle of (67) is reduced to yield the chlorin chromophore of chlorophyllide a (68). 

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