Company
Method
Detection
Range
Applications
-Compatibility
Assay protocol
Precautions-
Interferences
Absorbance 280nm
0.1-1 OD280nm/ml
Absorbance of aromatic amino-acids (Trp, Tyr and Phe at less extent).
Only for purified proteins with known absorptivity factor (Use
ExPASy ProtParam tool
to inquire E1% 280nm)
Read absorbance 280nm.
Nucleic acid, detergents, cofactors, phenolic compounds, pigments,
reducing agents, etc etc.
AMERSHAM-
BIOSCIENCE (PHARMACIA)
(# 80-6483-56)
2-D Quant Kit
0–50 µg
(1–50 µl)
Designed for the accurate determination of protein concentration
in samples prepared for electrophoresis and presence of detergents, Urea,
DTT, EDTA, Ampholites, etc, and many buffer components.
Quantitative precipitation of proteins while leaving interfering
substances behind.
BIO-RAD
(#500-0001年2月6日)
Bio-Rad Protein
Assay
(Modified
Bradford)
(pdf)
0.2–0.9 mg/ml
Compatible with reducing agents
(See list of compatible
reagents on BioRad cataloge)
Minimum incubation time 15minutes.
Assay wavelength 650-750nm
Detergents, basic buffers
BIO-RAD
(#500-0111/2)
DC Protein
Assay (Modified Lowry)
(pdf)
0.1–2.0 mg/ml
Compatible with detergents, basic buffers (See list of compatible
reagents on BioRad cataloge)
Minimum incubation time 15minutes.
Assay wavelength 595nm
Reducing agents
BIO-RAD
(#500-0121/2)
RC DC
Protein Assay (Modified Lowry) (pdf)
0.1–2.0 mg/ml
Compatible with detergents, reducing agents, Laemmli sample buffer
with 5% beta-mercaptoethanol, etc (See list of compatible reagents on BioRad
cataloge)
Minimum incubation time 15minutes.
Assay wavelength 650-750nm
EXPEDEON
BradfordUltra™ kit
(pdf)
2.0 mg/ml
low protein range
Compatible with 1% detergents, chelators, reducing agents and amines
Mix, vortex and read 595nm
GENO TECHNOLOGY
(#786-005)
Non-Interfering Protein AssayTM
Compatible with reducing agents(2ME, DTT), chelating agents EDTA
, detergents (non-ionic, anionic, cationic, and zwitterionic) , amines (Tris),
sugar, urea, ammonium sulfate, guanidine hydrochloride, guanidine thiocyanate,
drugs, antibiotics, cobalt, and numerous other agents.
Quantitative precipitation of proteins while leaving interfering
substances behind.
MOLECULAR PROBES
(N-6666)
Nano Orange Protein Quantitation
Kit (pdf)
10 ng/mL -
10 µg/mL
Little protein-to-protein variability. Compatible with the presence
of reducing agents and nucleic acids.
Mix and heat 10' 95ºC. Fluorescence emissions are measured directly
Unusually high concentrations of lipids in the sample can interfere.
This interference can be eliminated by acetone precipitation of the protein,
followed by delipidation with diethyl ether.
MOLECULAR PROBES
(C-6667)
CBQCA Protein Quantitation
Kit
(pdf)
10 ng/mL - 150 µg/mL
Functions well in the presence of lipids and detergents (to determine
the protein content of lipoprotein samples or lipid–protein mixtures)
OZ Biosciences
(#BA00100/
#BA00050)
Bradford
Protein Assay Kit
(pdf)
Low: 0.5 – 50 µg/mL
High: 50 – 1500 µg/mL
Determination of protein amount in the presence of
detergent (< 0.1%), reducing agents, Urea 4M,
Guanidine-HCl 2M, etc (see
Table 1)
0.14ml reagent + 0.01ml sample
Incubation 5' RT. Read 595nm
See
Table 1
PIERCE
(#23225)
BCA Protein Assay
(pdf)
0.5-20 µg/ml
Compatible with detergents solubilized proteins. Proteins on affinity
supports. Chaotropic agents, sugars, DNA, protease inhibitors
2ml reagent + 0.1ml sample
Incubation 30' 37ºC. Read 562nm
Reducing agents (can be eliminated with TCA,
see Protocol)
PIERCE
(#23235)
Micro-BCA Protein Assay
(pdf)
0.5-20 µg/ml
Compatible with detergents solubilized proteins. Proteins on affinity
supports. Chaotropic agents, sugars, DNA, protease inhibitors
1ml reagent + 1ml sample
Incubation 60' 60ºC. Read 562nm
Reducing agents (can be eliminated with TCA,
see Protocol)
PIERCE
(#23236)
Coomassie Plus Protein Assay
1-1500 µg/m
For quick estimation where accuracy is not important. Reducing agents.
Chaotropic and chelating agents, metals, protease inhibitors. DNA.
3 ml reagent + 0.1ml sample
Vortex and read 595nm
Detergents (
sometimes you can normalize using same detergent
concentration in blank and standarts)
PIERCE (#23200)
SIGMA
(#610-A)
Coomassie Protein Assay
(pdf)
BRADFORD
1-1500 µg/ml
For quick estimation where accuracy is not important:
great
variability. Compatible with reducing agents. Chaotropic and chelating
agents, metals, protease inhibitors. DNA.
5 ml reagent + 0.1ml sample
Vortex and read 595nm
Detergents (
sometimes you can normalize using same detergent
concentration in blank and standarts)
PIERCE
(#23240)
Modified Lowry Protein
Assay (pdf)
1-1500 µg/ml
Accurate. Compatible with protease inhibitors. DNA.
1 ml reagent + 0.2ml sample. Incubate 10' RT. Add 0.1ml Folin-Ciocalteu.
Incubate 30' RT. Read 750nm
Reducing agents (can be eliminated with TCA, see
Protocol , pdf)
and some detergents
PIERCE
(#23255)
Fluoraldehyde Protein/Peptide Assay
0.05-500 µg/ml
Compatible with reducing agents and some detergents. Chelating agents,
metals and sugars
2 ml reagent + 0.2ml sample. Mix and read fluorescence; excitation
330-390nm; emission 436-475nm.
Great variability. Cannot meassure in the presence of TRIS or Glycine
buffer.
ROCHE
(#1 767 283)
(#1 767 003)
ESL Protein Assay
(pdf)
20-800 µg/ml.
Detection limit 1µg/sample
Biuret-like reaction, detect peptide bonds. The assay is compatible
with several detergents. Coul be used for determination of peptides and immobilized
proteins
7 minutes reaction. Read at 485nm.
SIGMA
(#690-1)
BIURET
1-10 mg/ml
Very accurate and simple
Read 550nm
Glucose, Ammonium sulphate, Sulphydryl compounds, PO4 buffers
Folin-Ciocalteu reagent:
SIGMA (#F9252) - MERCK
LOWRY
10 µg/ml -
1 mg/ml
Very accurate
1 ml reagent + 0.2ml sample. Incubate 10' RT. Add 0.1ml Folin-Ciocalteu.
Incubate 30' RT. Read 750nm
Many detergents, reducing agents, EDTA, GuHCl, AmmSO4, >0.1M TRIS.
Interfernce elimination with
TCA or
DOC-TCA
SIGMA (#P5656)
Folin-Ciocalteu reagent:
SIGMA (#F9252) - MERCK
LOWRY-PETERSON
1-10 µg protein
Modified Lowry for membrane proteins. Compatible with detergents
and with the presence of all kind of interferents that can be eliminated
by DOC-TCA precipitation.
DOC-TCA precipitation of proteins before Lowry assay
BUTTERFLY
(coomassie staining into 3MM Whatman paper)
Very useful technique for proteins in all kind of solutions (like
PAGE-SDS sample buffer)
Dry samples into 3MM Whatman paper.Treat with coomassie staining
solution for ~30 min. Distain. Extracted ON with 3% SDS solution and read
at 590 nm