S30 Protocol
Introduction
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Materials
- 2 × YTPG
- 1L Milli-Q Water
- 2.99 g KH2 PO4
- 6.97 g K2 HPO4
- 19.82 g glucose
- 16 g tryptone
- 10 g yeast extract
- 5 g NaCl
- Buffer A:
- 10 mM Tris-acetate (pH 8.2)
- 14 mM magnesium acetate
- 60 mM potassium glutamate, and
- 2 mM dithiothreitol (DTT) or 2mM TCEP
- Buffer B:
- 1.2 mM ATP;
- 0.85 mM each of GTP, UTP, and CTP;
- 34.0 μg mL−1 L-5-formyl-5, 6, 7, 8-tetrahydrofolic acid (folinic acid);
- 170.0 μg mL−1 of E. coli tRNA mixture;
- 130 mM potassium glutamate;
- 10 mM ammonium glutamate;
- 12 mM magnesium glutamate;
- 2 mM each of 20 amino acids;
- 0.33 mM nicotinamide adenine dinucleotide (NAD);
- 0.27 mM coenzyme-A (CoA);
- 1.5 mM spermidine;
- 1 mM putrescine;
- 4 mM sodium oxalate;
- 33 mM phosphoenolpyruvate (PEP);
- 100 μg mL−1 T7 RNA polymerase
Procedure
- Preparing the Extract:
- Grow E. coli BL21 in 2 × YTPG media:
- (shake baffled flasks in a 37°C incubator with vigorous shaking at 250 rpm)
- Monitor by spectrophotometry until OD600 of 3.0 is reached (in the middle of exponential growth)
- Harvest the cells by centrifuging at 5000 x g at 4°C for 15 min
- Wash cells three with cold Buffer A (20mL for each gram of wet cells)
- Optional: After final wash and centrifugation, weigh and flash freeze in liquid nitrogen, and store at −80°C.
- [Re]suspend the pellets in 1 mL of Buffer A per 1 g of wet cell mass
- Transfer into 1.5 mL microtube and placed in an ice-water bath to minimize heat damage during sonication
- Llyse the cells at frequency of 20 kHz and 50% of amplitude. The input energy should add up to 556 Joules.
- Centrifuge the lysate at 12,000 RCF at 4°C for 10 min.
- Optional: incubate the supernatant at 37°C for 60 min with gentle shaking (250 rpm) and centrifuged at 15,000 RCF at 4°C for 15 min.
- Flash freeze in liquid nitrogen and stored at −80°C until use.
- Reaction Mixture
- Add the following components to nuclease-free water to make 55 mL of 2 X Buffer B:
- 0.005 g Folinic acid
- 0.026 g E. coli tRNA mixture
- 3.612 g Potassium glutamate
- 0.025 g Ammonium glutamate
- 0.305 g Magnesium glutamate
- 0.039 g Isoleucine
- 0.039 g Leucine
- 0.044 g Lysine
- 0.045 g Methionine
- 0.050 g Phenylalanine
- 0.036 g Threonine
- 0.061 g Tryptophan
- 0.035 g Valine
- 0.052 g Arginine
- 0.047 g Histidine
- 0.027 g Alanine
- 0.040 g Asparagine
- 0.040 g Aspartate
- 0.036 g Cysteine
- 0.044 g Glutamate
- 0.023 g Glycine
- 0.035 g Proline
- 0.032 g Serine
- 0.054 g Tyrosine
- 0.033 g NAD
- 0.033 g Spermidine
- 0.013 g Putrescine
- 0.080 g Sodium oxalate
- 0.832 g PEP
- 0.015 g T7 RNA Polymerase
- Reactions are carried out in a 1.5 mL microtube in the incubator at 37°C for 4 hours
- The standard reaction mixture consists of the following components in a final volume of 15 μL:
- 5.5 μL of 2X Buffer B
- 200 ng plasmid
- 4 μL of cell extract.
- 1.275 μL of 10mM NTP mix
- 1.485 μL of 2mM CoA (serial dilute 4μL of 50mM CoA in 96μL of ddH2O)
- 0.35mM ATP (How much is this?)
- top off with milliQ water to get to 15 μL
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