Page 274 - Biochemistry PharmD General

This porphin is substituted by different groups at positions
numbered from 1-8 to form the porphyrin. Depending upon the
groups (methyl, acetyl, propyl, butyl or venyl) present on these
positions different types of porphyrins are identified, that will
be seen during the synthesis of heme.

Properties of porphyrins

1. They act both as acids (-COOH) and bases (-NH2).
2. Their isoelectric pH is between 3-4.5.
3. Porphyrins are fluorescent and coloured due to presence of
alternating double bonds.
4. Porphyrinogens are colourless.

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