Recombinant His-6 RII Purification
(cAMP-dependent Protein Kinase A)

Susan Taylor (University of California at San Diego) January 3, 1997


	---Revised 7/95
	---Typical yield approximately 15 mg per liter of cells

Growing Cells and Expressing Protein

1. Prepare 6 liters of YT Media by placing 25 LB capsules/1 Liter 
	MQ H2O and autoclaving. Let the media cool to at least 37íC and 
	add to each flask 1 ml of filtered 100 mg/ml Ampicillin stock. 
	(0.6g Ampicillin/6ml H2O)  

2. Add 0.6 ml of sterile YT to the frozen bacterial stock. Vortex 
	well. Using sterile technique, add 100 ml of this solution to 
	each flask. If you inoculate the media that is at room 
	temperature, let the cells grow 5-7 hours in the shaker at 37íC 
	until OD600 is greater than 0.55 and less than 0.80. If you 
	inoculate media that is warm, the cells will grow to the 
	appropriate OD in less time than predicted.

***Alternate Method: Inoculate media that is at room temperature 
	after addition of sterile Ampicillin in the evening.  Place 
	flasks in the shaker and set the temperature to 37oC and RPM to 
	225.Set the timer to start the shaker early in the morning, ex: 
	3:00 or 4:00 a.m. Let the cells grow 5-7 hours at 37oC until 
	OD600 is between 0.55-0.80. Record the OD in your notes.

3. When cultures reach an OD600 of 0.55-0.80, induce them with 1.0 
	M IPTG (1.62g/6ml). Add 1 ml to each liter observing sterile 
 	technique. Final concentration of IPTG in the media ==> 1.0 
	mM. Grow for an additional 6 hours at 37oC.

4. Harvest the cells by spinning in 1 liter bottles for 11 minutes 
	at 5,000 RPM. Use Sorvall centrifuge. Measure and record the 
	average OD's before centrifuging

5. Consolidate the pellets in a 40 ml centrifuge tube. Label 
	completely and store the cells in the -70oC freezer.  

Isolation of Protein from Bacteria (Day 1)

1. Make 150 mls His6 Lysis Buffer.  Resuspend cell pellet in 60 
	mls/6L of His6 buffer [Dilute 10X His6 buffer, add 
	Benzamidine-HCL, leupeptin, TLCK, TPCK, PMSF add 54 ml b-me, 
	pH 8.0]

***If the resuspended cells are viscous, sonicate several times 
	with large probe then french press


2. Lyse the cells with two passes through a french press. Save 20 
	ml aliquot of the total cell lysate and record the total 
	volume.  

3. Spin the lysate for 40 minutes at 15,000 RPM in 50 ml 
	centrifuge tubes.  

4. While the lysate is spinning, equilibrate the Ni2+ resin. Use 
	15 mls of resin for a 6 L WT His6-RII prep, less for mutants. 
	Equilibrate by putting the resin in a 50 ml conical tube and 
	spinning down the slurry. Decant the supernatantand resuspend 
	the packed resin in His6 Lysis Buffer, pH 8.0. Repeat several 
	times. Load the resin onto a column or keep in conical tube for 
	batch method purification.

5. When lysate spin is complete, collect and combine the 
	supernatants. Take a 20 ml aliquot of the supernatant and 
	record the total volume of proteinsupernatant pooled. Save the 
	pellet from one of the centrifuge tubes and resuspend with 
	water in the same volume as the total cell lysate. Take a 20 ml 
	aliquot of the resuspended pellet and save.

6. Check the pH of the supernatant protein solution. Re-pH, if 
	necessary to 8.0. Load protein supernatant onto the column 
	slowly (1 ml/min). Collect the flow through and pass over 
	column again. Wash with 5 column volumes His6 lysis buffer.

***Alternatively, batch bind the supernatant with the Ni2+ Resin 
	for at least 30 minutes (longer if necessary...but not more 
	than 2 hours). Then, spin the resin down into one 50 ml conical 
	tube. Wash the resin in the conical tube 2 times with 30-40 mls 
	of His6-Lysis Buffer.

7. Step elute His6-RII from Resin (batch method or on column) 
	with:  
	1) 2 column volumes (Ex:30 + 30mls) His6 buffer + 20mM 
		imidazole, pH 7.0, 
	2) 2 column volumes His6 buffer + 50 mM imidazole, pH 7.0 

8. Elute the protein off the resin with 10 column volumes (150 
	mls) His6 buffer + 100 mM imidazole, pH 7.0. Collect small 
	fraction sizes, ex: 5 ml fractions. (can collect overnight)  

Day 2 of His6-RII Protein Prep


9. Run 10.0% SDS PAGE gels. Include standard, total cell lysate 
	(2ml), lysate pellet (2ml), lysate supernatant (2ml), flow 
	through (5ml), Wash #1 (20ml), Wash #2 (20ml), 20 mM Wash 
	(20ml), 50 mM Wash (20ml), and selected fractions (20ml).

10. Pool wanted protein (proteins that show little or no 
	contaminating 	bands) in a small beaker or conical tube. Step 
	Dialyze the protein 	in 1 L of: 20 mM Tris and 150 mM NaCl, pH 
	7.3 for six hours.  Then, dialyze the pooled protein in 2 L of: 
	20 mM Tris and 50 mM NaCl, pH 7.3, overnight.

Day 3 of His6-RII Protein prep: Cleaning up Protein

1. Check the pH of your Dialysis buffer, make sure it is still at 
	pH 7.3, if it isn't, record the pH and re-pH to 7.3.

2. Measure and record the concentration and volume of your 
	dialyzed pooled protein. Take a 20 ml aliquot.

3. Load up to 50-60 mgs of protein that has been filtered, onto 
	Mono Q 5/5 HR of FPLC.

4. Watch for peaks. Protein usually starts eluting between 35-45% 
	of Buffer B (1 M KPO4, pH 7.2). Make sure to hold the gradient 
	when peaks show and protein starts to elute. 

5. Run a 10.0% SDS PAGE Gel. Include standard, load (20ml), flow 
	through (20ml), and all necessary fractions from FPLC Run (2-
	30ml)

6. Dialyze protein for crystallographers in R Crystallography 
	Buffer and any excess in RII Storage Buffer:

7. Record total amount of protein recovered 

8. Record distribution of protein and amount distributed.


Buffers for His6 Recombinant RII Purification:


His-6 Lysis and Running Buffer:		1X		   	10X
	For Qiagen Resin		50 mM KPO4		500 mM KPO4
					300 mM NaCl		3 M NaCl
					5 mM b-me	 
					pH 7.0 or 8.0		pH 7.0 

His 6 Lysis and Running Buffer:	 	1X			10X
	For Invitrogen Resin		20 mM KPO4		200 mM KPO4
					500 mM NaCl		5 M NaCl
					5 mM b-me	 
					pH 7.0 or 8.0		pH 7.0 

**Add to all Lysis Buffers, for 150 mls (Not necessary for running 
	buffer): 

		10 mM Benzamidine (0.234 g/150 mls)
		1 mM or 0.5 mg/ml Leupeptin (75 ml/150 mls)
		70 mg/ml TPCK (150 ml of 7.0 mg/ml stock/150 mls)
		37 mg/ml TLCK (150 ml of 3.7 mg/ml stock/150 mls)
		0.5 mM PMSF (750 ml of 100mM stock/150mls)
	
Mono Q Buffer:		Buffer A			Buffer B
			20 mM Tris			1 M KPO4
			5 mM b-me			5 mM b-me 
			pH 7.3				pH 7.2

R Crystallography Buffer:	1X			10X
				10 mM MES		100 mM MES
				1 mM EDTA		10 mM EDTA
				1 mM EGTA		10 mM EGTA
				5 mM b-me, pH 6.0	pH 6.0

RII Storage Buffer:		1X			10X
				50 mM MES		500 mM MES
				150 mM NaCl		1.5 M NaCl
				1 mM EGTA		10 mM EGTA
				~20% Glycerol
				5 mM b-me	pH 6.8
  				pH 6.8

KMOPS 130:	1X			10X
		10 mM MOPS		100 mM MOPS
 		130 mM KCl		1.3 M KCl
		2 mM DTT or 5 mM b-me
		pH 6.5			pH 6.5

Optional: add 1 mM EDTA, 1 mM EGTA to 1X to stabilize RII
For all solutions, pH when cold and b-me to final solutions only