Wiki/Team:Warsaw/protocols

Purification of His_Z_alpha and His_Z_omega

Culture E. coli producer strain in 3 ml of liquid LB medium + kanamycin for 8 hours. Then use it to inoculate 200 ml of liquid LB medium + kanamycin supplemented with 0,5 mM IPTG and grow it overnight. In the morning spin down the culture (5000 RPM, 10 min, 4°C). Resuspend the pellet in PBS buffer and disrupt cells by sonication. Spin down sonication mixture (13200 RPM, 10 min, 4°C) and discard supernatant – purified protein is present in sonication debris. Resuspend it in sterile ice cold ddH2O and store at 4°C.

Culture, induce and disrupt E. coli in the same way as to purify His_Z_alpha. The protein is present in supernatant (about 10% of total protein) and can be added to selection medium without further purification. Nevertheless we purified it to determine how much exactly should be added:

1. Swinging of sonication products with Ni-nta-agarose bed for 2 hours at 4°C
2. Loading onto column
3. Washing of the bed with 20 mM imidasole buffer
4. Elution with 100 mM imidasole

metodą BCA

We use "Plasmid Mini" plasmid DNA isolation kit from A&A Biotechnology and follow the protocol of producer.

We use "Gel-Out" DNA isolation kit from A&A Biotechnology and follow the protocol of producer.

We use "Clean-Up" DNA purification kit from A&A Biotechnology and follow the protocol of producer.

We use "Genomic-Mini" universal genomic DNA isolation kit from A&A Biotechnology and follow the protocol of producer.

Keep the bacteria on ice during the procedure. Pour ca. 25 ml of bacteria into a falcon tube and spin in 4°C at 4 krpm, 8 min with prolonged acceleration and deceleration. Remove supernatant. The pellet mustn't run dry. You can pour another portion of bacteria onto it and spin again. After desired amount of bacteria in pellet is collected, add CaCl₂ in an amount of 10% of initial culture used for spinning. Suspend the pellet until no debris is visible on the bottom. Incubate 45 min on ice. Then spin 8 min at 4 kg and remove supernatant. Suspend the pellet in 3 ml CaCl₂ and divide into aliquots of 100 μl.

• Set up bacterial culture in 10 ml.
• Use the culture for inoculation of 1 L of medium and let it grow at 18°C until it reaches OD 0.6 - 0.8.
• Spin for 10 min at 6 krpm.
• Remove supernatant and suspend the pellet in 1 L of H₂O.
• Spin for 10 min at 6 krpm.
• Remove supernatant and suspend the pellet in 1 L of H₂O.
• Spin for 10 min at 6 krpm.
• Remove supernatant and suspend the pellet in 0.5 L of H₂O.
• Spin for 10 min at 6 krpm.
• Suspend the pellet in 20 ml 10% glycerol.
• Spin for 10 min at 6 krpm.
• Suspend the pellet in 3 ml 10% glycerol.
• Divide into aliquots of 40 μl and freeze in liquid nitrogen.

• Pour 100 ml H₂O plus desired amount of DNA into electroporation cuvette.
• Add 40 ul of bacteria.
Electroporate.
• Add 0.5 ml of LB.
• Incubate with shaking at 37°C.
• Plate.

Add desired volume of DNA to the 100 μl. culture in eppendorf tube. Incubate 30 min on ice. Heat shock for 90 s at 42°C. Incubate 10 min on ice. Add 0.9 ml of culture medium and let the bacteria grow at 37°C.

We use the following mixture:

1. appropriate volumes of vector and insert DNA (usually concentration of insert 3X higher than that of vector)
2. 2 μl of ligation buffer
3. 1 μl of T4 DNA ligase (purchased from Fermentas)
4. nuclease-free water