O/D 280	Conc (mg/ml)
Sample S1 (from the initial 6 mL Sample)	Approx. 0.54	0.54/0.5 = 1.08 mg/mL
Sample P2 (from the initial 3 mL Sample)	Approx. 0.3	0.3/0.5 = 0.60 mg/mL

Sample	Concentration (mg/ml)	Absorbance at O/D 280
A5	2.0 mg/ml	1.0
A4	1.5 mg/ml	0.75
A3	1.0 mg/ml	0.5
A2	0.5 mg/ml	0.25
A1	0.25 mg/ml	0.125
A0	0.0 mg/ml	0.0

Use:

your standard curve of ONP concentration,

the concentration of S1 and P2 you calculated earlier &

the fact that the reaction volumes for each assay were 3 mL and contained 0.5 mL of either S1 or P2.

to calculate the of MOLES of ONPG hydrolysed per sec per mg of protein for the S1 and P2 samples.

(Bear in mind that the absorption value reveals the MOLARITY of ONP in the solution but you need to work out the NUMBER OF MOLES released from ONPG by enzymatic hydrolysis in each reaction).

calculations: