precorrins

Precorrins are a group of structurally related cobalt-containing tetrapyrrole compounds that serve as biosynthetic intermediates in the synthesis of vitamin B12. Vitamin B12, also known as cobalamin, is an essential nutrient involved in various metabolic processes in humans and animals. The precorrins are produced in a complex enzymatic pathway that begins with uroporphyrinogen III.

There are several known precorrins, typically denoted by Roman numerals, such as precorrin-1, precorrin-2, precorrin-3, precorrin-4, precorrin-5, precorrin-6, and precorrin-7. Each precorrin represents a distinct stage in the ring contraction and methylation steps required to transform the larger porphyrinogen ring into the corrin ring characteristic of vitamin B12. These transformations involve a series of highly specific enzymatic reactions, including methylation, decarboxylation, and ring contraction.

The biosynthesis of precorrins and ultimately vitamin B12 occurs in bacteria and archaea, as animals cannot synthesize this vitamin de novo and must obtain it from their diet. Studying the precorrin pathway provides valuable insights into the intricate biochemical mechanisms of life and the evolution of complex metabolic pathways. Understanding these intermediates can also be relevant for developing strategies to enhance vitamin B12 production in microorganisms for industrial or therapeutic purposes.