ML (Modified Lowry) Protein Assay

G-Biosciences’ ML (Modified Lowry) Protein Assay is based on the widely cited protein assay by Lowry et. al. (1951). The ML Protein Assay is compatible with a wide variety of detergents used in protein research in addition to other common reagents such as EDTA and Tris (see tables 1 and 2). The assay is supplied with either traditional bovine serum albumin (BSA) protein standard, pre-diluted BSA protein standards, non animal protein standard or bovine ɣ globulin protein standard. 
 

A CL (Compatible Lowry) Protein Assay is available for samples containing reducing agents (such as dithiothreitol (DTT), ß-mercaptoethanol and TCEP) and a wide variety of commonly used laboratory agents that are known to interfere with Lowry’s protein assays (see tables 1 and 2).
 

Table-1: A selection of compounds and their maximum concentrations compatible with the ML and CL Protein Assay.

                     Reagent   ML Protein Assay   CL Protein Assay
Amino Acids Compatible -
Ammonium Sulfate 0.5M 40%
β-Mercaptoethanol X 5%, 15%*
Brij® 35 1% 1%
Calcium Chloride 0.05M -
CHAPS 1% 4%
CHAPSO 1% 1%
CTAB - 1M
Deoxycholate 1% -
Digitonin 0.3% -
DTT 0.001M 0.1M, 0.35M*
EDTA 0.025M 0.1M
Glycerol - 30%
Guanidine.HCl 0.4M 6M
Guanidine Thiocynate - 6M
HEPES - 0.1M
Hydrochloric Acid 0.5M -
Imidazole - 0.5M
Iodoacetamide - 15mM
Laemmli Buffer (w/5% β-Mercaptoethanol) - Compatible
NP-40 2% -
Octaethyleneglycol dodecyl ether 0.2% -
Octyl Glucoside 1% -
Phosphate Buffer - 0.2M
Sarcosyl - 1%
SDS 10% -
Sodium Azide 0.05% 0.1M
Sodium Chloride - 0.5M
Sodium Hydroxide 0.5M 2.5M
Sucrose - 30%
TCEP - 15mM
Thesit® 1% 2%
Thiourea - 2M
Tributylphosphine (TBP) 0.002M -
Tris (pH 8) 0.1M 0.5M
Triton® X-100 1% 3%
Triton® X-114 1% 3%
Tween® 20 1% 2%
Urea 4M 8M
Zwittergent® 3-12 - 1.5M
-, not tested; X, not compatible; *, two washes (optional).


 

Table 2: ML & CL Protein Assay are compatible with strong chaotropic extraction buffers

Buffer Composition
4M Urea, 1% SDS, 10mM EDTA, 0.8% β-Mercaptoethanol
6M Urea, 2M Thiourea, 4% CHAPS
6M Urea, 2M Thiourea, 4% NP-40
1% Sarcosyl, 0.8 β-Mercaptoethanol, 4M Guanidine Thiocyanate, 10mM EDTA
6M Urea, 2M Thiourea, 2% CHAPS, 2% ND SB 201
6M Urea, 2M Thiourea, 2% CHAPS, 2% SB 2 10
 

Features
  • Protein quantitation in the presence of detergents 
  • Quick 15 minute incubation
  • Increased color stability (color will not change more than 5% in 1 hour or 10% in 2 hours)
  • Linear response 0.2 – 1.5 mg/ml
  • One simple protocol without cumbersome sample preparation or buffer exchange steps
  • Convenient kit provides all necessary reagents for 250 standard (5ml) assays or 1000 microtube (1.5-2 ml) assays

Applications​
  • Estimate protein during protein purification, electrophoresis, cell biology, molecular biology, and other research applications.
  • Suitable for protein samples containing common laboratory agents, such as chelating agents (EDTA), detergents, amines (Tris), sugars and many other agents.
  • Suitable for samples containing chaotropic agents such as urea, thiourea, guanidine hydrochloride, guanidine thiocyanate, ammonium sulfate, drugs, antibiotics, cobalt, and numerous other agents and extraction buffers.
  • Suitable for determination of protein concentration in cellular fractions, tissue & cell lysates and chromatography purification fractions.

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Protocol
786-1075
786-1076
786-1082
786-1083
Material Safety Data Sheet
786-1075
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786-1076
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786-1082
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786-1083
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1. Alam, Aftab, “A Model for Formulation of Protein Assay,” Analytical Biochemistry, 203 (1992): 121-126.
2. 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. 
3. Peterson, Gary L., “Review of the Folin Phenol Protein Quantitation Method of Lowry, Rosebrough, Farr, and Randall,” Analytical Biochemistry, 100 (1979): 201- 220.
Catalog Description Size Price(USD) Qty
786-1075
ML Protein Assay with BSA Standard 1,000 Assays
$85.00
786-1076
ML Protein Assay with Non Animal Protein Standard 1,000 Assays
$85.00
786-1082
ML Protein Assay with Pre-Diluted BSA Protein Standard 1,000 Assays
$106.00
786-1083
ML Protein Assay with Bovine ɣ Globulin Standard 1,000 Assays
$93.00