I am confused by your question. The concentration is about 100u/mg but you give a range of weight of material which looks the same. I assume that the product has a catalogue number then an amount  on the bottle looking like G1234-500mg in which case you have 500mg so to get a concentration of X U/ml multiply a weighed amount of material by 100-300 then dissolve it in 1 ml then dilute some of that 1ml by a dilution factor of X. So 1mg /ml would be about 150u/ml and to get 2.4 u/ml dilute by 150/2.4

Enzymes from Sigma formulated as ammonium sulfate suspensions are usually sold by the number of units, rather than by the number of mg. For example, glutathione reductase product G3664 can be purchased in 100, 500, and 2500 unit containers. Measure the volume of the suspension in the container. Divide the number of units by the volume to get units/ml. Then dilute the thoroughly mixed suspension by the appropriate amount to get 2.4 U/ml.

If the ammonium sulfate is a problem in your assay, then centrifuge some of the suspension and resuspend the pellet in buffer to remove most of the ammonium sulfate.

Hi Nida! Here the walkthrough how i understand it:

-Volume of GR in the bottle: 60 uL

-Protein concentration: 9.5 mg/ml (=9.5 ug/uL --> 60 uL contain then 570 ug or 0.57 mg of GR)

-Relative activity: 189 U/mg (--> you have 0.57 mg GR in your bottle, therefore you have a total of 107.7 U if GR)

-If you would take out 6 uL of your GR from the bottle (10% of the contents), this would correspond to 10.77 U.

-10.77 U/(2.4 U/mL)= 4.49 mL --> if you add 4.49 mL of water (or buffer) to this 6 uL of GR, you have your desired enzyme concentration of 2.4 U/mL and can perform (5.49/0.15=29.9) experiments with 29 samples.

-If you have more than 29 samples to analyse, i.e. 59 samples, take out 12 uL of GR from the bottle.

-if you have less than 29 samples to analyse, i.e. 14 samples, take out only 3 uL of GR from the bottle.

-0the maximum amounts of samples you can analyse with the whole bottles will be 299 samples.

Good Luck!