RC DC Protein Assay
Instruction Manual
Catalog # 500-0119
500-0120
500-0121
500-0122
For Technical Service
Call Your Local Bio-Rad Office or
in the U.S. Call 1-800-4BIORAD
(1-800-424-6723)
Section 1 Introduction
The RC DC Protein Assay is a colorimetric assay for protein quantitation with all
the functionality of the original DC Protein Assay. This assay is based on the
Lowry1assay but has been modified to be reducing agent compatible (RC) as well
as detergent compatible ( DC).
Section 2 Product Description
RC Reagents Package, includes
• RC Reagent I (250 ml)
• RC Reagent II (250 ml)
(Sufficient for 500 standard assays or 2,000 microfuge tube assays)
RC Reagent I contains UPPA-I
RC Reagent II contains UPPA-II
UPPA is a trademark of Geno Technology, Inc.
Section 3 Reagent Compatibility
The listed reagents were tested and found to be compatible with the RC DC
Protein Assay. The presence of one or more of these substances may change the
response of the protein to the assay reagents. Thus the protein standard should
always be prepared in the same buffer as the protein sample.
Reagents One Wash Two Washes (Optional)
Dithiothreitol (DTT) 100 mM 350 mM
Tributylphosphine (TBP) 2 mM β-mercaptoethanol 5% 10%
Sequential Extraction Buffer 2
Sequential Extraction Buffer 3
Laemmli Buffer
(with 5% β-mercaptoethanol) Full Strength -
CHAPS 2% -
*
Tween 20
Triton X-100
EDTA 100 mM Imidazole 500 mM -
Tris, pH 8.4 500 mM NaOH 2.5 M -
**
♦
Not Compatible Full Strength
♦♦
Not Compatible Full Strength
2% -
2% -
*
Tween is a registered trademark of ICI Americas, Inc.
**
Triton is a registered trademark of Rohm and Haas.
♦
40 mM Tris, 8 M urea, 4% (w/v) CHAPS, 0.2% (w/v) Bio-Lyte 3/10 ampholyte, 2 mM TBP
(Catalog #163-2103)
♦♦
40 mM Tris, 5 M urea, 2 M thiourea, 2% (w/v) CHAPS, 2% (w/v) SB 3-10, 0.2% (w/v)
Bio-Lyte 3/10 ampholyte, 2 mM TBP (Catalog #163-2104)
1
Section 4 Assay Instructions
Standard Assay Protocol (5 ml)
1
Add 20 µl of DC Reagent S to each 1 ml of DC Reagent A that will be needed
for the run. This solution is referred to as Reagent A´. Each standard or sample
assayed will require 510 µl of Reagent A´.
(Reagent A´ is stable for one week even though precipitate will form after one
day. If precipitate forms, warm the solution and vortex. Do not pipet the
undissolved precipitate as this will likely plug the tip of the pipet and alter the
volume of Reagent A´ added to the sample.)
2
Prepare 3-5 dilutions of a protein standard from 0.2 mg/ml to 1.5 mg/ml
protein. A standard curve should be prepared each time the assay is
performed.
(For best results, the standards should always be prepared in the same buffer
as the sample.)
3 Pipet 100 µl of standards and samples into clean, dry test tubes.
4 Add 500 µl RC Reagent I into each tube, vortex. Incubate the tubes for 1
minute at room temperature.
5 Add 500 µl RC Reagent II into each tube, vortex. Centrifuge the tubes at
15,000xg for 3-5 minutes.
6 Discard the supernatant by inverting the tubes on clean, absorbent tissue
paper. Allow the liquid to drain completely from the tubes.
7 Add 510 µl Reagent A´ to each tube, vortex. Incubate tubes at room
temperature for 5 minutes, or until precipitate is completely dissolved. Vortex
before proceeding to the next step.
8 Add 4 ml of DC Reagent B to each tube and vortex immediately. Incubate at
room temperature for 15 minutes.
9 After the 15 minutes incubation, absorbances can be read at 750 nm. The
absorbances will be stable for at least 1 hour.
Microfuge Tube Assay Protocol (1.5 ml)
1 Add 5 µl of DC Reagent S to each 250 µl of DC Reagent A that will be needed
for the run. This solution is referred to as Reagent A´. Each standard or
sample assayed will require 127 µl of Reagent A´.
(Reagent A´ is stable for one week even though precipitate will form after one
day. If precipitate forms, warm the solution and vortex. Do not pipet the
undissolved precipitate as this will likely plug the tip of the pipet and alter the
volume of Reagent A´ added to the sample.)
2 Prepare 3-5 dilutions of a protein standard from 0.2 mg/ml to 1.5 mg/ml
protein. A standard curve should be prepared each time the assay is
preformed.
(For best results, the standards should always be prepared in the same buffer
as the sample.)
2
3 Pipet 25 µl of standards and samples into clean, dry microfuge tubes.
4 Add 125 µl RC Reagent I into each tube, vortex. Incubate the tubes for 1
minute at room temperature.
5 Add 125 µl RC Reagent II into each tube, vortex. Centrifuge the tubes at
15,000xg for 3-5 minutes.
6 Discard the supernatant by inverting the tubes on clean, absorbent tissue
paper. Allow the liquid to drain completely from the tubes.
7 Add 127 µl Reagent A´ to each microfuge tube, vortex. Incubate tubes at room
temperature for 5 minutes, or until precipitate is completely dissolved. Vortex
before proceeding to the next step.
8 Add 1 ml of DC Reagent B to each tube and vortex immediately. Incubate at
room temperature for 15 minutes.
9 After the 15 minutes incubation, absorbances can be read at 750 nm. The
absorbances will be stable for at least 1 hour.
Section 5 Storage
RC Reagent I and RC Reagent II should be stored at room temperature (20°C to
30°C) away from direct sunlight. Both reagents have a shelf life of 12 months.
(Also see DCProtein Assay Instruction Manual for storage conditions for DC
Protein Assay Reagent A, Reagent B and Reagent S.)
3
Section 6 Troubleshooting Guide
Questions
1 May I use a wavelength other than
750 nm?
2 What should I do if the protein
pellet is still soft after centrifugation
for 3 to 5 minutes?
3 What can I do to minimize
interference from supernatant
carry-over?
Recommendations
Yes, absorbance can be measured at
650-750 nm.
Increase the centrifugation duration to
6-10 minutes. Protein pellet may take
longer to dissolve after the addition of
Reagent A´.
Option #1:
A second wash can be performed as
follows:
Standard Assay
After step #6, repeat step #4 with
500 µl of Reagent I, repeat step #5
with 160 µl of Reagent II, repeat
step #6 before going on to step #7.
Microfuge Tube Assay
After step #6, repeat step #4 with
125 µl of Reagent I, repeat step #5
with 40 µl of Reagent II, repeat step
#6 before going on to step #7.
Option #2:
At step #6: to maximize supernatant
removal, discard supernatant by
aspiration before going on to step #7.
Option #3:
After step #6, dry tubes under
vacuum to reduce residual
supernatant before going on to
step #7.
Note: Also see DCProtein Assay Instruction Manual for additional
troubleshooting recommendations.
4
Section 7 References
1 Lowry, O.H., Rosebrough, N.J., Farr, A.L., and Randall, R.J., “Protein
Measurement with the Folin Phenol Reagent,” Journal of Biological Chemistry,
193 (1951):265-275.
Section 8 Order Information
Catalog # Items
500-0121 RC DC Protein Assay Kit I, includes contents
of RC DC Protein Assay Reagents Package
and Bovine Gamma Globulin Standard
500-0122 RC DC Protein Assay Kit II, includes contents
of RC DC Protein Assay Reagents Package
and Bovine Serum Albumin Standard
500-0120 RC DC Protein Assay Reagents Package,
includes RC Reagent I (250 ml), RC Reagent
II (250 ml), DC Reagent A (250 ml), DC
Reagent B (2 L), and DC Reagent S (5 ml)
500-0119 RC Reagents Package, includes RC Reagent
I (250 ml) and RC Reagent II (250 ml)
500-0117 RC Reagent I, 250 ml
500-0118 RC Reagent II, 250 ml
500-0111 Bio-Rad DC Protein Assay Kit I, includes
contents of Bio-Rad DC Protein Assay
Reagents Package and Bovine Gamma
Globulin Standard
500-0112 Bio-Rad DC Protein Assay Kit II, includes
contents of Bio-Rad DC Protein Assay
Reagents Package and Bovine Serum
Albumin Standard
500-0116 Bio-Rad DC Protein Assay Reagents
Package, includes Reagent A (250 ml),
Reagent B (2 L) and Reagent S (5 ml)
x x x
x x
x
x
x
x x
x x x
x x
x
x
x
x
x x
x x
x
x
xx xx
xxx
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Related Materials
Catalog # Product Description
500-0001 Bio-Rad Protein Assay Kit I, includes Dye Reagent Concentrate
(450 ml) and Bovine Gamma Globulin Standard
500-0002 Bio-Rad Protein Assay Kit II, includes Dye Reagent Concentrate
(450 ml) and Bovine Serum Albumin Standard
500-0006 Bio-Rad Protein Assay Dye Reagent Concentrate, 450 ml
500-0005 Protein Standard I, Bovine Gamma Globulin
500-0007 Protein Standard II, Bovine Serum Albumin
223-9950 Disposable Polystyrene Cuvettes, 3.5 ml, 100
223-9955 Disposable Polystyrene Cuvettes, 1.5 ml, 100
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Bio-Rad Laboratories
2000 Alfred Nobel Dr., Hercules, CA 94547
510-741-1000 4110107 Rev A
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