Biochemistry?

Question

Using the millimolar absorptivity of PNPP, convert ΔA/min to mM/min (ie. rate of increase in concentration of PNPP) from the Beer-Lambert law.

500µL of 0.4mM PPNP
Linear Equation: y = 0.0007x + 0.0056
ΔA/s = 0.0007
ΔA/min = 0.0418

Correction:

500µL of 0.4mM PNPP in 2.3mL 0.2M Tris-HCl

Answer 1

Re-write the equation as

A= 0.0007C+0.0056 =>
ΔΑ =0.0007* ΔC =>
ΔΑ/Δt = 0.0007 *ΔC/Δt =>

ΔC/Δt = (1/0.0007)* ΔA/Δt
so provided that the equation corresponds to mM as you said,

ΔC/Δt = 0.0418/0.0007 = 59.71 mM/min

I think you mean PNP; PNPP is para-nirtophenylphosphate which is colourless and is the substrate of phosphatases. PNP is para-nitrophenol which in alkaline solutions is mainly in the form of the yellow p-nitrophenoxy anion. Thus I expect you would measure PNP concentration with a spectrophotometer, and [PNP] to increase whereas [PNPP] to decrease.

Answer 2

OMG...I just finished biochem..and struggled. Good luck to you!!