The substrate analogue S-adenosyl-l-homocysteine (SAH) was co-crystallised with SAM hydroxide adenosyltransferase from Pyrococcus horikoshii. Of the two active site water molecules one appears to be structural and the other is a candidate for nucleophilic attack, to become the C5′ adenosyl hydroxyl group. The data support a mechanism in which the Arg–Asp ion pair is important for positioning both water molecules.
- enzyme catalysis
Deng, H., McMahon, S. A., Eustaquio, A. S., Moore, B. S., Naismith, J. H., & O'Hagan, D. (2009). Mechanistic insights into water activation in SAM hydroxide adenosyltransferase (duf-62). ChemBioChem, 10(15), 2455-2459. https://doi.org/10.1002/cbic.200900369