In-Gel Procedure
PSR In-gel Digestion 05/07/07
Reagents
diH2O 50% 100 mM Ammonium Bicarbonate (AB) / 50% Acetonitrile (ACN)
100% 100 mM AB
100% ACN
10mM Dithiothreitol (DTT) in 100 mM AB
55mM Iodoacetamide (IAA) in 100 mM AB
100% 25 mM AB
Trypsin Digestion Solution (make fresh): Thaw a 50 µL vial of 0.1 ug/ µL trypsin, and add 200 µL of 100 mM AB, 4 l 0.5 M CaCl2, and 146 µL diH2O
Digestion Buffer: 5.0 mL of 100 mM AB, 100 µL of 0.5 M CaCl2, 4.90 mL H2O
Pre-Digestion
Solutions removed after each incubation unless otherwise noted
(2x) Add diH2O wash of whole gel for 15 min
Cut out gel bands and put into vials
(2x) Add 100ul of 50% 100 mM AB / 50% ACN and incubate for 30 min on shaker
Put sample in Speed-Vac to remove excess solution
Add 100 µL of 10 mM DTT and incubate for 45 min @ 56ºC
Add 100 µL of 55 mM IAA cover with foil and incubate for 30 min on shaker
Add 500 µL of 50% 100 mM AB / 50% ACN and incubate for 15 min on shaker
Put sample in Speed-Vac to remove excess solution
Digestion
Add 20 µL of Trypsin Digestion solution and incubate for 15 min @ 4ºC If gel plug isn’t completely re-swelled add an additional 10 µL of Trypsin solution and repeat the incubation until the gel plug won’t absorb any more solution then remove any excess solution
Add 60 µL of Digestion Buffer and incubate @ 37ºC overnight, more digestion buffer can be added to cover the gel slices, don’t remove solution after incubation
Short Extraction Method
Add 3 µL of neat FA added to the above solution, bath-sonicate for 15min at 37oC, pull off and save solution for mass spec analysis
Long Extraction Method
Pull off solution from the overnight digestion into a separate vial
Add 50 µL of 25 mM AB gel pieces, bath-sonicate for 15 min @ 37ºC, don’t remove solution after incubation
Add 50 µL of 50% ACN to the above solution, bath-sonicate for 15 min @ 37ºC, remove supernatant after incubation and combine it with the solution from the overnight digestion
Concentrate the extracts to approx. 10 µL in a Speed-Vac (don’t let them go dry) and save for mass spec analysis