Formation of Carbon Monoxide and Bile Pigment in Red and Blue-Green Algae

Abstract

Five blue-green and one red algal species produced carbon monoxide during photosynthetic growth. The blue-green algae synthesized CO and phycocyanobilin in equimolar quantities at identical rates. The red alga, Porphyridium cruentum, incorporated z-aminolevulinic acid-5-14C into phycoerythrobilin and CO. The ratio of the specific radioactivity of phycoerythrobilin to that of CO, and the kinetics and stoichiometry of phycocyanobilin and CO formation suggest that linear tetrapyrroles in plants are derived by the porphyrin pathway via the intermediate formation of heme. The similarity between bile pigment production in algae and in mammalian systems is discussed.Phycocyanobilin and phycoerythrobilin are linear tetrapyrroles covalently linked to apoproteins occurring in the photosynthetic apparatus of red, blue-green, and cryptomonad algae (17). These compounds are structurally related to bilirubin, the principal mammalian bile pigment derived from hemoglobin in senescent erythrocytes (1,14, 18,19). It is known that CO is produced endogenously in normal man (24), and that approximately 1 mole of CO is produced per mole of heme catabolized (2, 1 1). CO formation has been described in algae (6,12,15), in fungi (23, 33), and in higher plants (22,34). CO produced in the fungus, Aspergillus niger, has been shown to arise from the breakdown of rutin to phloroglucinol and protocatechuic acid (23). Nevertheless, in most reports concerning algae and higher plants, the metabolic origin of CO has not been established. We have shown that in the green algae, Cyanidium caldarium, CO is a by-product of phycocyanobilin formation (31). The present paper describes some quantitative and kinetic parameters of CO and bile pigment formation in five species of blue-green algae and in the red alga, Porphyridium cruentum.

Metabolism of δ-Aminolevulinic Acid in Red and Blue-Green Algae

“…The data show that C4 and C5 of ALA and C2 and C3 of succinic acid appear to be equally incorporated into all of the amino acids detected. As expected from previous work on ALA incorporation into phycocyanobilin and CO in these organisms (23,24), ALA utilization via the porphyrin pathway was greatest in C.…”

“…During an investigation of phycocyanin biosynthesis in bluegreen algae, we observed a 1: 1 relationship between the moles of phycocyanobilin and CO produced (23). Incorporation of administered ALA-5-'4C into algal bile pigment and CO was practically nil.…”

Production and consumption of carbon monoxide in a eutrophic lake1

“…At present we cannot even exclude the possibility that light-dependent metabolic processes might contribute to the CO production in freshwater lakes (e.g. CO formation during the biosynthesis of linear tetrapyrroles from heme precursors in cyanobacteria: Troxler and Dokos 1973). In addition to the light-and 02-dependent CO production in the epilimnion and metalimnion of the lake, CO was also produced in the dark and anaerobic hypolimnion.…”

“…Oscillutoriu in the aerobic parts of the lake), although phototrophs should have the capacity for light-dependent CO production (Loewus and Delwiche 1963;Troxler and Dokos 1973;Bauer et al 1980). Most likely light intensity was limiting for CO production, due to turbidity of the lake water.…”

Investigation of the sources and sinks of atmospheric methane

“…al ., 1979., , Guenther et al, 2000. Proposed mechanisms include degradation of chlorophyll (Troxler and Dokos, 1973) and photooxidation of plant cellular material (Bauer et al, 1979). Without specific information on plant type or regions we spatially apportioned the emissions based on vegetation land cover.…”