FIG. 4.

TrbB and HP0525 display distinct substrate affinities. (A) TrbB was incubated under standard conditions with labeled [α-³²P]dATP (final concentration, 200 μM). Unlabeled NTPs or dNTPs were added to the reaction in fivefold molar excess, and dATP hydrolase activity was determined as described in Materials and Methods. (B) HP0525 was incubated under standard conditions with labeled [γ-³²P]ATP (final concentration, 500 μM). Unlabeled NTPs or dNTPs were added to the reaction in fivefold molar excess, and ATP hydrolase activity was determined as described in Materials and Methods.