Common Hydrogen Bond Interactions in Diverse Phosphoryl Transfer Active Sites
Figure 2
Models used to test the dependence of hyperconjugation and O3β―Pγ bond length on enzyme-ligand interactions.
N-methylacetamide (A) was used to model a (neutral) protein backbone amide hydrogen bond to O3β, using methyl triphosphate to model an NTP nucleotide. Structures 2 (B) and 3 (C) were used to investigate the effects of protonation at the γ-oxygens. Additional active site hydrogen bonds, represented in Structures 4 through 6 (D–F), were used to assess the secondary effects of different types of Oγ hydrogen bonds. Acetamide (E) 1-propylaminium (F) were used to model asparagine and lysine side chains respectively. Structure 7 (G) was used to investigate the impact of hydrogen bonding at a nonbridging β-oxygen on hyperconjugation and O3β―Pγ bond length. Hydrogen bonds are shown with dashed red lines. White = hydrogen, gray = carbon, red = oxygen, blue = nitrogen, orange = phosphorus.