Biosynthetic studies of substituent homologation in bacteriochlorophylls c and d.
Administration of carbon-13 and carbon-14 labeled glutamate, glycine, and methionine to Chlorobium vibrioforme forma thiosulfatophilum strain D have demonstrated operation of the C5 and C1 metabolic pathways in bacteriochlorophyll c and bacteriochlorophyll d biosynthesis in this organism, with glutamate providing the delta-aminolevulinic acid for macrocycle synthesis and glycine providing the source of the extra homologation at the 4-, 5-, and delta-positions (via S-adenosylmethionine). Further evidence showing that the bacteria appear to adjust the homologue composition of their antenna bacteriochlorophylls in response to varying growth conditions is presented. Timing of these changes within a single culture is consistent with a light adaptation mechanism, which predicts that degree of alkylation is directly proportional to light intensity in the culture; other factors influencing pigment composition during the lifespan of a single culture may also be operating, and these are discussed.
Huster
M S
MS
Department of Chemistry, University of California, Davis 95616.
Smith
K M
KM
D001419:Bacteria / Q000378:metabolism*; D001429:Bacteriochlorophylls / Q000096:biosynthesis*; D002247:Carbon Isotopes; D002250:Carbon Radioisotopes; D002734:Chlorophyll / Q000031:analogs & derivatives*; D005971:Glutamates / Q000378:metabolism; D018698:Glutamic Acid; D005998:Glycine / Q000378:metabolism; D007553:Isotope Labeling / Q000379:methods; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008715:Methionine / Q000378:metabolism; D011865:Radioisotope Dilution Technique
D001429:Bacteriochlorophylls; D002247:Carbon Isotopes; D002250:Carbon Radioisotopes; D005971:Glutamates; D002734:Chlorophyll; D018698:Glutamic Acid; D008715:Methionine; D005998:Glycine