In: Biology
You want a 50 µL reaction volume containing 1X reaction buffer, 1 µg DNA, and 10 Units of enzyme.You have a plasmid with a concentration of 250 ng/µL, 10X reaction buffer, and your enzyme concentration is 20,000 units/mL.
How many µL of water, reaction buffer, DNA and enzyme would you combine to set up that reaction? Please show work
Total volume of reaction= 50 microliters
a) Given is 10X reaction buffer
Hence, to obtain 1X concentration, 10X buffer should be diluted 1: 10
C1V1=C2V2
10X X V1= 1X X 50 microliters
V1= 1 X 50/10= 5 microliters
5 microliters of 10X reaction buffer is added
b) Required DNA concentration is 1 microgram DNA/50 microliters
Given is 250 ng/microliters of plasmid DNA
1ng = 0.001 microgram
250 ng= 250 X 0.001= 0.25 microgram
Plasmid DNA= 0.25 microgram/ microliters
Amount of plasmid DNA added= 0.25 x 4= 1 microgram
Hence, 4 ml of 250 ng/ microliters of plasmid DNA is added to give a final concentration of 1 microgram of DNA in total volume of 50 microliters.
c) Given stock enzyme concentration is 20,000 units/ml
Required enzyme concentration is 10 units/50 microliters
Enzyme concentration in stock= 20000 units/ ml= 20000 units/ 1000 microliters = 20 units/ microliters
Hence, 0.5 microliters (10 units/ microliter) will be added to the total 50 microliters reaction volume to obtain 10 units/ microliters of enzyme
d) Distilled water= 50 microliters – (volume of enzyme + DNA + reaction buffer)
Distilled water= 50 –(5+4+0.5)= 50-9.5= 40.5 microliters
Final reaction of 50 ml:
5 microliters of 10X reaction buffer
4 microliters of 250 ng/ microliter plasmid DNA
0.5 microliters of 20000 units/ml enzyme
40.5 microliters of distilled water