ReadyPrep™2-D Cleanup Kit
Instruction Manual
Catalog #163-2130
For technical service, call your local Bio-Rad office, or
in the US, call 1-800-4BIORAD (1-800-424-6723)
Bio-Rad Laboratories, Inc.
2000 Alfred Nobel Dr.
Hercules, CA 94547 USA
(510) 741-1000
1-800-424-6723
4110143 Rev A
Table of Contents
Section 1 Introduction……………………………………...1
Section 2 Kit Specifications…………………………......2 –3
Section 3 Storage Conditions………………………..........3
Section 4 Instructions for Use………………….............4–9
Section 5 Appendix……………..……………............10–15
Section 6 Product Information………………….........16–17
Section 1
Introduction
The ReadyPrep 2-D cleanup kit facilitates the preparation
of low conductivity samples suitable for isoelectric focusing
(IEF) and 2-D gel electrophoresis. Additionally, the kit
concentrates proteins from samples that are too dilute,
allowing for higher protein loads that can improve spot
detection. The ReadyPrep 2-D cleanup kit can be used
with virtually any protein sample to generate improved 2-D
results by reducing streaking, background staining, and
other gel artifacts associated with substances
contaminating 2D/IEF samples. The entire process can be
completed in approximately one hour and does not
produce alterations in the isoelectric point of proteins. The
procedure works by quantitatively precipitating and
concentrating proteins in a sample while leaving behind
and washing away substances like ionic detergents, salts,
nucleic acids, lipids, and plant-derived phenolic
compounds, all of which are known to interfere with IEF.
The precipitation is not affected by the presence of
detergents, chaotropes or other common buffers, salts and
reagents used to extract or treat proteins. After
precipitation, the proteins are washed and then
resuspended in the IEF/2D-compatible rehydration/sample
buffer of choice, ready for isoelectric focusing or Laemmli
sample buffer, ready for SDS-PAGE.
1
Section 2
Kit Specifications
Each ReadyPrep 2-D cleanup kit provides sufficient reagent
to purify 50 samples of 100 µl, each sample containing up
to 500 µg of protein. The kit contains the components
listed below. Certificates of analysis or MSDS forms are
available upon request.
Items Supplied With Kit
One bottle containing 15 ml of precipitation agent 1*
One bottle containing 15 ml of precipitation agent 2
One tube containing 2 ml of wash reagent 1
One bottle containing 50 ml of wash reagent 2*
One tube containing 0.25 ml of wash 2 additive
One instruction manual
*Care should be exercised when handling precipitation
agent 1 and wash reagent 2.
Precipitation agent 1 is corrosive!
Wash reagent 2 is flammable and an irritant!
2
Items Required But Not Provided:
• 1.5 ml microcentrifuge tubes
• Microcentrifuge capable of spinning at 12-16,000 x g at
4°C.
• Rehydration/sample buffer (see Section 5 for recipes and
Section 6 for premixed, ready-to-use rehydration/sample
buffers)
• Vortex mixer
• ReadyPrep proteomic grade water or other ultrapure
water
• RC DC™ Protein Assay (Bio-Rad catalog #500-0121 or
#500-0122)
Section 3
Storage Conditions
Store the kit at room temperature. Wash reagent 2 must be
stored at -20°C for at least 1 hr prior to use. For
convenience, store wash reagent 2 in a -20°C freezer.
3
Section 4
Instructions for Use
4.1 Protocol for Sample Volumes up to 100 µl
Use 1.5 ml microcentrifuge tubes for processing the protein
samples. Maintain the sample tubes in an ice bucket during
each step of the procedure unless otherwise specified.
Always position the microcentrifuge tubes in the centrifuge
in the same orientation (for example: cap hinge facing out ward) so that the protein pellet remains on the same side of
the tube after each spin. This will minimize loss of protein
pellets during centrifugation and washing steps.
For best results, the protein concentration of the sample
should be determined before beginning (see step 1). We
recommend the Bio-Rad RC DC Protein Assay for protein
quantitation because the assay is suitable for the widest
variety of samples and works in the presence of
detergents, reducing agents, and other agents that
interfere with other protein assays.
Refer to Section 5.1. for guidelines on the quantity of
sample needed with immobilized pH gradient (IPG) strips of
different lengths and with different staining(detection)
methods. This will help determine what the starting amount
of protein should be.
4
1. Transfer 1–500 µg of protein in a final volume of
100 µl into a 1.5 ml microcentrifuge tube.
Note: Sample quantities > 500 µg of protein may reduce the
efficiency of the cleanup leading to poor-quality IEF.
2. Add 300 µl precipitating agent 1 to the protein
sample and mix well by vortexing. Incubate on ice for
15 min.
Note: When adding solution, do not touch protein sample
with the pipet tip. The protein may precipitate on the tip
causing sample loss.
3. Add 300 µl precipitating agent 2 to the mixture of
protein and precipitating agent 1. Mix well by
vortexing.
Note: When adding solution, do not touch protein sample
with the pipet tip. The protein may precipitate on the tip
causing sample loss.
4. Centrifuge the tube(s) at maximum speed
(> 12,000 x g) for 5 min to form a tight pellet. Remove
the tube promptly once the centrifuge stops so that
the pellet does not disperse.
5. Without disturbing the pellet, remove and discard the
supernatant using a pipet.
6. Position the tube in the centrifuge as before (i.e., cap
hinge and protein pellet facing outward) and centrifuge
for 15–30 sec to collect any residual liquid at the
5
bottom of the tube. Use a pipet to carefully remove the
remaining supernatant.
7. Add 40 µl of wash reagent 1 on top of the pellet.
Position the tube in the centrifuge as before and
centrifuge at maximum speed (> 12,000 x g) for 5 min.
Note: A precipitate may form along the tube wall. In these
cases, vortex and/or pipet wash solution over the pellet
several times to ensure entire pellet is thoroughly washed.
8. With a pipet, remove and discard the wash.
9. Add 25 µl of ReadyPrep proteomic grade water or
other ultrapure water on top of the pellet. Vortex the
tube 10–20 sec. Protein pellets may disperse, but will
not dissolve in the water.
10. Add 1 ml of wash reagent 2 (prechilled at -20°C for at
least 1 hr) and 5 µl of wash 2 additive. Vortex the
tube for 1 min.
Notes: Protein pellets will not dissolve in wash reagent 2.
If wash reagent 2 is not completely chilled, quantitative
recovery may be affected.
11. Incubate the tube at -20°C for 30 min. Vortex the tube
for 30 sec every 10 min during the incubation period.
12. After the incubation period, centrifuge the tube at top
speed for 5 min to form a tight pellet. Remove and
6
discard the supernatant. Centrifuge the tube briefly
(15–30 sec) and remove and discard any remaining
wash. The pellet will appear white at this stage. Air-dry
the pellet at room temperature for no more than 5 min
(the pellet will look translucent once sufficiently dry).
Note: Do not over-dry pellets. Over-dried pellets will be
difficult to resuspend.
13. Resuspend each pellet by adding an appropriate
volume of 2-D rehydration/sample buffer to the pellet.
Notes: Refer to Section 5.2 for recipes of typical 2-D
rehydration/sample buffers or Section 6 for a list of
convenient premade 2-D rehydration/sample buffers
available from Bio-Rad.
Consult Section 5.1 for a guide to selecting the volume of
2-D rehydration/sample buffer to use to resuspend the
protein pellet.
For SDS-PAGE, add an appropriate volume of Laemmli
sample buffer to the pellet, vortex the tube until the pellet
is dissolved and then heat the sample for 5 min at
95-100oC.
Vortex the tube for at least 30 sec. Incubate the tube
at room temperature for 3–5 min. Vortex the tube
again for ~1 min or pipet the solution up and down to
fully resuspend.
Notes: With some samples (large pellets or over-dry pellets)
the pellet may be difficult to resuspend. In these cases,
sonication can be used to speed the process.
7
At the end of the process, some pellet fragments may
remain undissolved. When using a urea/thiourea-based 2-D
rehydration/sample buffer, all the protein is extracted from
the pellet if the above protocol is followed.
14. Centrifuge the tube at maximum speed for 2–5 min at
room temperature to clarify the protein sample. The
supernatant can be used directly for IEF in IPG strips
or in IEF gels. Store any unused or remaining protein
sample in a clean tube at -80°C for later analysis.
4.2 Processing Dilute Samples or Samples Greater
Than 100 µl
The above protocol (Section 4.1) can be scaled to almost
any volume of original sample. For best results with larger
sample volumes, follow the additional recommendations
listed below for each step.
Maintain the sample tubes in an ice bucket during each
step of the procedure unless otherwise specified.
Always position the tubes in the centrifuge in the same
orientation so that the protein pellet remains on the same
side of the tube after each spin. This will minimize loss of
protein pellets during centrifugation and washing steps.
Use only polypropylene, polyallomer, or glass tubes for
processing large volumes as the wash reagent 2 interacts
with many plastics. Screwcap tubes are preferred to
8
reduce possible spilling during vortexing and the incubation
at -20°C. A Nalgene Oak Ridge-type tube made of
polypropylene copolymer is an example of an appropriate
tube. The volume of the tube should be at least 12 times
the original volume of the sample.
Step 2. For each volume of sample use 3 volumes of
precipitating agent 1.
Step 3. For each volume of sample use 3 volumes of
precipitating agent 2.
Step 7. Wash the protein pellet by adding 3–4 times the
pellet volume of wash reagent 1.
Step 8. Add enough ReadyPrep proteomic grade water or
other ultrapure water to just cover the protein pellet.
Step 9. Add 1 ml of wash reagent 2 (prechilled at -20°C
for at least 1 hr) for every 0.1 ml of original sample.
Additionally, the volume of wash reagent 2 must be at least
10 times the volume of water used in Step 9. Add 5 µl of
wash 2 additive (use only 5 µl of wash 2 additive
regardless of the volume of sample).
9
Section 5
Appendix
5.1 2-D Rehydration/Sample Buffer Volume
In the final step for this kit, all samples are resuspended in
a 2-D rehydration/sample buffer (Section 5.2). To best
determine the volume of 2-D rehydration/sample buffer to
use, consider the questions listed below. To assist with
these calculations, the table that follows indicates
appropriate volumes of 2-D rehydration/sample buffer
needed to rehydrate IPG strips of specific lengths and the
approximate amounts of protein required for detection
using silver stain or Coomassie Blue G-250 stain. An
example illustrates how to calculate the volume of 2-D
rehydration/sample buffer required.
1. What is the quantity of protein precipitated in the tube?
2. For 2-D electrophoresis experiments using IPG strips,
what length strip will be used?
3. What is the pH range of the IPG strip to be used?
4. How complex is the protein sample?
5. What staining or detection method will be used?
(for example, Bio-Safe™ Coomassie stain, silver stain,
etc.)
10
IPG strip length 7 cm 11 cm 17 cm 18 cm 24 cm
Rehydration 125 µl 185 µl 300 µl 315 µl 410 µl
volume per strip
Protein load– 5–20 µg 20–50 µg 50–80 µg 50–80 µg 80–150 µg
Silver stain
Protein load– 50–100 µg 100–200 µg 200–400 µg 200–400 µg 400–800 µg
Coomassie G-250
Sample calculation : If you precipitate 100 µg of protein and are going to
run 7 cm pH 3–10NL IPG strips (125 µl per strip) and silver stain the 2-D
gels, then you may want to solubilize the protein pellet in ~900 µl of
rehydration/sample buffer, which is enough to rehydrate about seven
7 cm IPG strips (~14 µg/strip). However, if you are planning to use a
24 cm pH 3–10NL IPG strip, then you may want to solubilize the protein
pellet in 410 µl of rehydration/sample buffer, which is enough to rehydrate
one 24 cm IPG strip (100 µg/strip). In this simple example, sample
complexity and IPG strip pH range were not addressed. As a general
rule, increased protein loads may be required for micro-range IPG strips
and for samples of higher protein complexity.
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5.2 Preparation of 2-D Rehydration/Sample Buffers
The 2-D rehydration/sample buffer is not a component of
this kit, but is necessary for resuspending the final protein
pellet. It is not provided in the kit because different protein
samples can require different rehydration/sample buffers.
For convenience, a selection of 2-D rehydration/sample
buffer formulas are provided below. The general-purpose
2-D rehydration/sample buffer is also available
preformulated from Bio-Rad (ReadyPrep 2-D starter kit
rehydration/sample buffer, 10 ml, catalog #163-2106).
Users of the ReadyPrep protein extraction kit (membrane I),
catalog #163-2088 or the ReadyPrep protein extraction kit
(cytoplasmic/nuclear), catalog #163-2089 should use the
protein solubilization buffer (PSB) and PSB diluent provided
with these kits to solubilize the protein pellet. PSB is a
proprietary strongly chaotropic 2-D rehydration/sample
buffer (refer to Section 5.2.2.2 for preparation instructions).
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5.2.1. General-Purpose 2-D Rehydration/Sample
Buffer for Most Samples.
(8 M Urea, 2% CHAPS, 50 mM DTT, 0.2% Bio-Lyte3/10
ampholyte, 0.002% bromophenol blue)
Component Final Concentration Amount to Make 2 ml
Urea (FW 60.06) 8 M 0.96 g
CHAPS 2% (w/v) 0.04 g
DTT (FW 154.3) 50 mM 15.4 mg
100X Bio-Lyte 0.2% (w/v) 20 µl
3/10 ampholyte*
Bromophenol Blue 0.002% (w/v) 4 µl of a 1%
Proteomic grade 1.25 ml
water
*
Use an ampholyte buffer that corresponds to the pH range of the IEF
separation to be performed. For example, ReadyStrip™micro-range buffers
with ReadyStrip micro-range IPG strips and ReadyStrip 7-10 buffer with
ReadyStrip pH 7-10 IPG strips. Bio-Lyte 3/10 ampholyte can be used with
all other ReadyStrip IPG strip pH ranges.
(w/v) solution
13
5.2.2. Strongly Chaotropic 2-D Rehydration/Sample
Buffers for Highly Hydrophobic Proteins.
5.2.2.1. Standard Strongly Chaotropic Buffer
(7 M urea, 2 M thiourea, 4% CHAPS, 50 mM DTT, 0.2%
Bio-Lyte 3/10 ampholyte, 0.002% Bromophenol Blue).
Component Final Concentration Amount to make 2 ml
Urea (FW 60.06) 7 M 0.84 g
Thiourea (FW 76.12) 2 M 0.304 g
*
CHAPS
DTT (FW 154.3) 50 mM 15.4 mg
100X Bio-Lyte 0.2% (w/v) 20 µl
3/10 ampholyte
Bromophenol Blue 0.002% (w/v) 4 µl of a 1%
Proteomic grade 1.1 ml
water
*
Other neutral or zwitterionic detergents can also be used at concentrations
of 1% to 2% (w/v) to improve solubilization of membrane and hydrophobic
proteins. Examples are n-octyl- β-D-glucopyranoside, SB3-10 (N-decyl-N,Ndimethyl-3-ammonio-1-propanesulfonate) and ASB14 (tetradecanoylamidopropyl-dimethylammonio-propane-sulfonate).
**
Use an ampholyte buffer that corresponds to the pH range of the IEF
separation to be performed. For example, ReadyStrip™micro-range buffers
with ReadyStrip micro-range IPG strips and ReadyStrip 7-10 buffer with
ReadyStrip pH 7-10 IPG strips. Bio-Lyte 3/10 ampholyte can be used with
all other ReadyStrip IPG strip pH ranges.
4% (w/v) 0.08 g
**
(w/v) solution
14
5.2.2.2. Protein Solubilization Buffer (PSB) .
Protein solubilization buffer (PSB) and PSB diluent are
provided with ReadyPrep protein extraction kit
(membrane I) and ReadyPrep protein extraction kit
(cytoplasmic/nuclear) to solubilize the protein pellet after
using the ReadyPrep 2-D cleanup kit. PSB is a proprietary,
strongly chaotropic 2-D rehydration/sample buffer that will
solubililze both hydrophilic as well as hydrophobic proteins.
To make 2 ml of complete 2-D rehydration/sample buffer,
add 1.1 ml of PSB Diluent to each 1 g of PSB powder.
Note: Before weighing out the PSB powder, shake the bottle
vigorously for 10-15 sec to break up any clumps and to ensure
a uniform blend of the different components.
Mix the solution until the powder is completely dissolved
(the tube can be warmed to speed dissolution of the solids,
but do not allow the temperature to exceed 30°C). Add
DTT, Bio-Lyte ampholyte and Bromophenol Blue as
directed in Section 5.2.2.1 to complete the preparation of
the Buffer.
15
Section 6
Product Information
Catalog # Description
Sample Preparation Kits
163-2130 ReadyPrep 2-D Cleanup Kit, 50 preps
163-2089 ReadyPrep Protein Extraction Kit
(Cytoplasmic/Nuclear), 50 preps
163-2088 ReadyPrep Protein Extraction Kit
(Membrane I), 50 preps
163-2087 ReadyPrep Protein Extraction Kit
(Signal), 50 preps
163-2090 ReadyPrep Reduction Alkylation Kit
Protein Quantitation Kits (also see bulletin 2610)
500-0121 RC DC Protein Assay Kit I, 500 standard
assays, bovine γ-globulin standard
500-0122 RC DC Protein Assay Kit II, 500 standard
assays, bovine serum albumin standard
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Buffer Components
161-0611 Dithiothreitol (DTT), 5 g
163-2101 Tributylphophine (TBP), 200 mM, 0.6 ml
161-0460 CHAPS, 1 g
161-0731 Urea, 1 kg
161-0716 Tris, 500 g
161-0302 Sodium Dodecyl Sulfate (SDS), 1 kg
163-2094 100X Bio-Lyte 3/10 Ampholyte, 1 ml
163-2091 ReadyPrep Proteomic Grade Water
2-D Rehydration/Sample Buffers
163-2106 ReadyPrep 2-D Starter Kit
Rehydration/Sample Buffer, 10 ml,
containing 8 M urea, 2% CHAPS,
50 mM DTT, 0.2% Bio-Lyte 3/10
ampholyte, Bromophenol Blue
Coomassie is a trademark of Imperial Chemical Industries, PLC.
The ReadyPrep 2-D cleanup kit is based on Perfect-FOCUS™technology,
which is owned by Geno Technology, Inc. (patent pending). Perfect-FOCUS
and FOCUS are trademarks owned by Geno Technology, Inc.
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