Question

The ATP assays for the substrate saturation curve shown above where performed in 1 mL reactions. Each assay tube contained 25 µL of a 1:100 diluted enzyme solution prepared from 3.5 mg/mL ATPase stock solution (MWATPase = 25,000 g/mol).

What is the diluted enzyme concentration?

Answer 1

ATPase are enzymes which catalyze the hydrolysis of ATP.

Structure of ATP

Pi - phosphate groups

Stock concentration = 3.5 mg/mL or 3500 ug/mL

Dilution = 1:100

Volume of enzyme added in each tube = 25 uL or 0.025 mL

Total volume in each tube = 1 mL

Concentration of enzyme after dilution = 35 ug/mL

Using dilution formula. M1V1 = M2V2

where, M1, M2 = initial and final concentrations

V1, V2 = initial and final volumes

35 ug/mL x 0.025 mL = M2 x 1 mL

M2 = (35 x 0.025)/ 1 = 0.875 ug/mL

Thus, the final concentration of ATPase in the tube = 0.875 ug/mL