GTP cyclohydrolase

GTP cyclohydrolases are enzymes that catalyze imidazole ring opening of guanosine triphosphate (GTP).

[1] This reaction is the committed step in the biosynthesis of multiple coenzymes (such as riboflavin and folate), tRNA bases, and the phytotoxin toxoflavin.

[1] Several GTP cyclohydrolases exist, which sometimes synthesize different products for different purposes: These enzymes require divalent cations for catalysis.

[1]

Guanosine triphosphate (GTP), the substrate of GTP cyclohydrolases