| Abstrakt: |
A comparative study has been made of the ability of nucleated erythrocytes (chicken) and of different tissues, as homogenates of fresh tissues (dog and human) and as "acetone powders" of tissues (several species) to synthesize porphyrinogens-porphyrins from either glycine and acetate or succinate or from ALA. With the exception of the nucleated erythrocytes, the tissues studied had no measurable ability to form copro- and protoporphyrins from glycine and acetate or succinate However, the various tissues can form copro- and protoporphyrins from ALA, and in the following order: nucleated erythrocytes > liver > adrenal > spleen > kidney > heart > skeletal muscle > brain. The spleen of the human infant was extremely active. Non-nucleated erythrocytes (dog) are active to the coproporphyrin(ogen) stage. Acetone powders of the same tissues show similar porphyrin-forming capacities. Little variation in porphyrin-forming activity was found among tissues from different mammalian species, but avian (pigeon) tissues appear to be more active in this respect. From these results it appears that different tissues, with the exception of the nucleated erythrocyte, may synthesize porphyrinogens-porphyrins from ALA, but only to a limited extent from glycine and acetate or succinate. ALA may probably be supplied to these tissues preformed, this apparently occurring primarily in the nucleated erythrocyte (bone marrow). The porphyrinogen-porphyrin-forming capacity of a given tissue appears to be related to the heme content and/or turnover rate in that tissue. |
