Uroporphyrinogen III cosynthetase. Evidence for the existence of a polypyrrolic substrate in soybean callus tissue

Protochlorophyll and Chlorophyll Biosynthesis in Cell-Free Systems from Higher Plants

“…The uroporphyrinogen formed during the lag phase accounted for only part of the porphobilinogen consumed. The authors concluded that a pre cursor of uroporphyrinogen must have accumulated during the lag phase (95,96). They looked for such an intermediate in the incubation mixture and detected a uv absorbing species similar in its absorption properties to monopyrroles.…”

“…They looked for such an intermediate in the incubation mixture and detected a uv absorbing species similar in its absorption properties to monopyrroles. Elu tion from Sephedex G-15 indicated a probable molecular weight of 600 to 700, suggesting a tripyrrole (95). In the presence of porphobilinogen the intermediate was converted into uroporphyrinogen III by the cosynthetase (95).…”

“…Elu tion from Sephedex G-15 indicated a probable molecular weight of 600 to 700, suggesting a tripyrrole (95). In the presence of porphobilinogen the intermediate was converted into uroporphyrinogen III by the cosynthetase (95). Uambias & BatHe (96) also performed detailed kinetic studies on the porpho bilinogenase and partially purified uroporphyrinogen I synthetase.…”

Polypyrroles formed from porphobilinogen and amines by uroporphyrinogen synthetase of Rhodopseudomonas spheroides

“…BatlIe and co-workers (Llambias & Batlle, 1970;Stella etal., 1971) found that enzymes from soya-bean callus consumed porphobilinogen initially at a much faster rate than expected for the amount of porphyrin formed, suggesting the presence of intermediates. Two apparent tripyrroles have been isolated.…”

Relationship of porphobilinogen deaminase activity to chlorophyll content and development of 'Heinz 1350' tomato fruit

“…While the deaminase by itself will consume porphobilinogen and produce uroporphyrinogen I (14,17,20,21,30,32), no uroporphyrinogen is formed when the cosynthase is incubated with porphobilinogen. This is because porphobilinogen is not consumed by the cosynthase, and, furthermore, it will not convert uroporphyrinogen I to the type III isomer (9,23,37,38,46 The deaminase is very heat-stable, and maximum activity has been demonstrated at 65C in extracts isolated from Chlorella regularis (46) and 67c in wheat germ extracts (20). The deaminase enzyme lost only fifteen percent of its activity when incubated for fifteen minutes at 75c (20), and similar results were reported by Shioi et al (46).…”