Cbikp Structure Modified tetrapyrroles are key elements for life since they serve as cofactors and pigments in several biological processes. Well-known examples are hemes, siroheme, vitamin B12, coenzyme F430 and chlorophyll, whose assembly requires insertion of a specific metal ion into the tetrapyrrolic structure, via chelatase enzymes. Cobaltochelatases act in the vitamin B12 biosynthetic pathway, cobalt being inserted into the tetrapyrrole ring. The X-Ray crystallographic structure from the cobaltchelatase CbiKP from Desulfovibrio vulgaris was determined, and this is the first structure of...