Abstract
Summary
1. Crystalline porphobilinogen (PBG) incubated with rat liver homogenate has been shown to be converted to at least 11 different porphyrins, the majority of which is copro- and protoporphyrin, with a smaller proportion of uroporphyrin. The total amount at 22 hours incubation in each of 3 experiments was slightly in excess of 50% of the PBG added. 2. At least half of the porphyrin in the 3 and 9-hour incubated samples were present in a non-fluorescing form. These porphyrin precursors were readily converted to porphyrin by addition of iodine or exposure to ultra-violet light. 3. The major part of the porphyrins isolated was isomer type III. The proportion of type I isomer increased with continued incubation. 4. The supernatant suspension obtained by centrifugation at 3000 rpm for 20 minutes was essentially as active as the whole homogenate, in the conversion of PBG to porphyrin.
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