Formation of β,γ-methylene-7,8-dihydroneopterin 3′-triphosphate from β,γ-methyleneguanosine 5′-triphosphate by GTP cyclohydrolase I of Escherichia coli

Abstract

GTP cyclohydrolase I of Escherichia coli converts [β,γ-methylene]GTP to a fluorescent product that is characterized as [β,γ-methylene]dihydroneopterin triphosphate. Interaction between the GTP analog and the enzyme gave a K i of 3.0 μ m, which may be compared to the K m of 0.1 μ m for GTP. This new analog of dihydroneopterin triphosphate may, in turn, be converted to the same greenish-yellow pteridines (compounds X, X1, and X2) that are obtained from dihydroneopterin triphosphate. Because of its stability to phosphatase action, this analog may be useful for studies in pteridine metabolism.