Functions of the Porphin Side Chains

Porphin by itself has no catalytic function except when iron is inserted into the ring. The specific side chains at the positions of the pyrrole rings undoubtedly are also related to the functioning of this pigment. Two approaches have been used to determine their function. One has been to vary the side chains and note how this influences the function of the modified heme protein. Another approach has been to supply modified porphins to organisms which require iron protoporphin for a growth factor and note whether these modified porphins could replace iron protoporphin in the catalytic functions essential for growth. 

CHANGES OF SIDE CHAINS AS AFFECTING ACTIVITY OP HEME 

The effect of side chains on the activity of peroxidase has been studied recently by Theorell, Bergstrom, and Akeson (135). The normal prosthetic group, iron protoporphin IX, was replaced by other iron porphins on the 

Effect op Porphin Side Chains on Activity op Hemoclobin and Peroxidase and on Growth of Strtgomonas/oscicttiota 

Compounds Side chains Per cent activity Support of growth of  

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