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NON-IONIC DETERGENTS
Non-ionic Detergents
2
NON-IONIC DETERGENTS OFFERED BY BACHEM
Detergents are amphipathic molecules that contain both
polar and hydrophobic groups. All detergents are char-
acterized as containing a hydrophilic “head” region and
a hydrophobic “tail” region. In contrast to purely polar
or non-polar molecules, amphipathic molecules exhibit
unique properties in water. Their polar group forms hydro-
gen bonds with water molecules, while the hydrocarbon
chains aggregate due to hydrophobic interactions. These
properties allow detergents to be soluble in water and also
to solubilize hydrophobic compounds in water.
NON-IONICDETERGENTS
Bachem offers alkanoyl-N-methyl-
glucamides (MEGA’s), alkylglycosides,
and oligoethyleneglycol monoalkyl
ethers. Besides these types of non-
ionic detergents, a choice of lipids and
phospholipids can be ordered at our
online shop: shop.bachem.com
3
Overview Detergents
Detergents are used in biochemistry to
solubilize membrane-bound proteins and
facilitate their isolation and recrystalliza-
tion [1,2]. They can be used to introduce the
purifi ed protein molecules into lipo-
somes and to determine their properties
or enzymatic activities in reconstitution
experiments [3,4]. Detergents can further
be used to facilitate protein solubilization in
biological assays or to form microemulsions
for electrochemical studies [5].
There are hundreds of detergents that can
be used in biochemical experiments. The
selection of the “right” detergent for a given
application is therefore diffi cult and still
rather empirical [1,3,6,7].
The following physical properties of deter-
gents can help making the right decision.
Critical Micelle Concentration (CMC)
The CMC of a detergent is the minimum
concentration at which micelles form. The
CMC is also an indicator of the strength
detergents bind to proteins; i.e., low values
indicate strong binding and high values
indicate weak binding.
The CMC is infl uenced by pH, temperature,
ionic strength and impurities in the solution
[1,7,8]. The CMC values reported in litera-
ture (e.g. [9]) are therefore only correct for
the given conditions.
• A high CMC is desirable when dialysis
across a membrane is necessary and in
other situations where rapid removal or
displacement of detergent is desired.
• A low CMC is desirable if the ratio of free
to bound detergent has to be minimized, e.g.
in the measurement of binding strength of
detergent to protein.
• The CMC of a given detergent can be
determined by different methods including
the measurement of light scattering, sur-
face tension, hydrodynamic properties, and
changes in absorbance or fl uorescence
upon dye solubilization [10].
Aggregation Number (N)
The aggregation number is the average
number of detergent monomers in one
micelle and permits the determination of
the micelle size and the molecular weight.
The micelle size is important in gel fi ltration
experiments since the separation of differ-
ent proteins according to size is done more
easily in the presence of a detergent with a
small micellar size [6]. This value is depen-
dent on temperature and ionic strength.
Cloud Point (cp)
The cloud point is the temperature above
which detergent micelles form super-
aggregates and the solution separates in a
solvent-rich phase and a solvent-depleted
phase [7]. This phase separation can be
exploited for protein extraction.
CnE
mProduct
C5E
1Ethyleneglycolmonopentylether
C5E
2Diethyleneglycolmonopentylether
C5E
3n-Pentyltrioxyethylene
C6E
1Ethyleneglycolmonohexylether
C6E
3n-Hexyltrioxyethylene
C6E
4n-Hexyltetraoxyethylene
C6E
5n-Hexylpentaoxyethylene
C7E
3n-Heptyltrioxyethylene
C7E
4n-Heptyltetraoxyethylene
C7E
5n-Heptylpentaoxyethylene
C8E
1Ethyleneglycolmonooctylether
C8E
3n-Octyltrioxyethylene
C8E
4n-Octyltetraoxyethylene
C8E
5n-Octylpentaoxyethylene
C8E
nn-Octylpolyoxyethylene
C10
E4
n-Decyltetraoxyethylene
C10
E5
n-Decylpentaoxyethylene
C12
E5
Dodecyl pentaethylene
glycolether
n-Alkyloligooxy-
ethylenes
(Oligoethyleneglycol
monoalkyl ethers)
CnE
m: C
n = CH
3(CH
2)
n-1
alkyl chain
Em
= (OCH2CH
2)
mOH
oligoethyleneglycol
In particular, the octyl
oligooxyethylenes C8E
4,
C8E
5, and C
8E
n (Octyl-
POE, n = 2 to 9) have
been shown to be of
great value for solubili-
zation and crystalliza-
tion of proteins, such as
porin, from E. coli outer
membranes.
Non-ionic Detergents
4
Critical Micellar Temperature (cmt)
The critical micellar temperature is defi ned
as the minimum temperature at which a
detergent can form micelles in water. At
temperatures below cmt, some detergents
exist as insoluble liquid crystals. This pa-
rameter has to be taken into consideration
in protein purifi cation at low temperatures.
Classifi cation
Detergents can be grouped in four main
classes according to the properties of their
head group:
• Anionic
• Cationic
• Zwitterionic (Ampholytic)
• Non-Ionic
Anionic and cationic detergents typically
modify protein structure to a greater extent
than the other two classes.
Zwitterionic detergents are unique as they
offer the combined properties of ionic and
non-ionic detergents. Like non-ionic deter-
gents the zwittergents do not possess a
net charge, they lack conductivity and
electrophoretic mobility and do not bind
to ion-exchange resins. However, like ionic
detergents, they are effi cient at breaking
protein-protein interactions.
The group of non-ionic detergents, pre-
sented in this brochure, is special in the
sense that they can be classifi ed as “mild”
detergents because they are less
likely to denature proteins than ionic deter-
gents. On the other side they are less effec-
tive at disrupting protein aggregation.
The most important properties of non-ionic
detergents are:
• Uncharged hydrophilic head group.
• Better suited for breaking lipid-lipid and
lipid-protein interactions.
• Considered to be nondenaturants.
• Salts have minimal effect on micellar size.
• Solubilize membrane proteins in a gentle
manner, allowing the solubilized proteins to
retain native subunit structure, enzymatic
activity and/or nonenzymatic function.
• The CMC of a non-ionic detergent is
relatively unaffected by increasing ionic
strength, and increases substantially with
rising temperature.
The amphipathic
nature of detergents is
shown as an example
with n-Dodecyl-β-
D-maltoside (DDM,
Product P-1170).
Maltose constitutes
the hydrophilic head
and the alkyl chain the
hydrophobic tail.
Hydrophilic head
Hydrophobic tail
MILD NON-IONIC DETERGENTS FOR THE SOLUBILIZATION OF MEMBRANE-BOUND PROTEINS
5
Practical Considerations
Denaturation Effect
When characterizing a protein in its native
state and studying its functions, the dena-
turation effect of detergents is an important
point. It is diffi cult to classify detergents into
denaturizing and non-denaturizing classes
and to ascribe these properties to specifi c
features of either the monomeric or the
micellar structure of the molecule [8]. The
denaturation effect of a detergent depends
further on the structure of the protein itself.
The following general statements can be of
practical use:
• Non-ionic detergents with polyoxyethylene
or sugar head groups do usually not dena-
turize proteins.
• Ionic detergents are nearly always denatur-
ants at temperatures and concentrations
used for complete membrane solubilization.
They further dissociate complex proteins in
their polypeptide chains. This effect may be
useful in the separation and identifi cation of
the different subunits of a protein [6].
Detergent Amount / Concentration
The appropriate amount of detergent (con-
centration) must be used for a successful iso-
lation of a protein. The membranes undergo
different stages of disintegration with an
increasing amount of detergent:
• At concentrations of around 0.1 mg to 1 mg
detergent per mg membrane lipid, selective
extraction of membrane proteins can occur
but the membrane bilayer remains essentially
intact.
• At higher concentrations of about 2 mg
detergent per mg lipid, solubilization of
the membrane occurs. This results in the
formation of soluble lipid-protein-detergent,
protein-detergent and lipid-detergent mi-
celles [1].
• 10 mg detergent per mg lipid or more should
be used for delipidation (i.e. a maximal ex-
change of the lipid bound to the protein with
detergent). At this point protein-detergent mi-
celles are formed, each containing essentially
only one protein molecule. These micelles can
then be separated by methods based on size,
charge density, binding affi nity and solvent
partitioning [11].
In the solubilization process the binding of
detergent to protein or membranes (solubi-
lization) has to compete with the self-asso-
ciation of detergent molecules to micelles
[1,12]. The exact amount of detergent
needed to achieve a certain effect depends
on the CMC, the micelle size, the tempera-
ture, the nature of the membrane and the
detergent [1]. The detergent monomers do
not participate in membrane solubilization,
but they are required to obtain the mono-
mer-micelle equilibrium [11].
To calculate the effective detergent-to-lipid
ratio and the amount of detergent available
for solubilization, the amount of detergent
forming micelles must be taken into
account:
• Detergents with low CMC; the effective
amount of detergent essentially equals the
total amount of detergent added, since very
little detergent exists as monomers.
• Detergents with a high CMC; the effec-
tive amount of detergent equals the total
amount of detergent added minus the
monomer concentration (essentially the
CMC).
References
[1] A. Helenius and K. Simons, Biochim.
Biophys. Acta 415, 29 (1975)
[2] R.M. Garavito and J.A. Jenkins, Structure
and Function of Membrane Proteins (E.
Quagliariello and F. Palmieri, eds.), Elsevier
Science Publishers B.V., Amsterdam (1983)
[3] C. Tanford and J.A. Reynolds, Biochim.
Biophys. Acta 457, 133 (1976)
[4] M. Hanatani et al., J. Biochem. 95, 1349
(1984)
[5] M.O. Iwunze et al., Anal. Chem. 62, 644
(1990)
[6] A. Helenius et al., Methods Enzymol. 56,
734 (1979)
[7] J.M. Neugebauer, Methods Enzymol. 182,
239 (1990)
[8] L.M. Hjelmeland, Methods Enzymol. 124,
135 (1986)
[9] P. Mukerjee and K.J. Mysels, National
Standards Reference Data Series, Vol. 36,
US National Bureau of Standards (NSRDS-
NBS 36), Washington (1971)
[10] A. Chattopadhyay and E. London, Anal.
Biochem. 139, 408 (1984)
[11] D. Lichtenberg et al., Biochim. Biophys.
Acta 737, 285 (1983)
[12] C. Tanford, J. Mol. Biol. 67, 59 (1972)
Despite the large num-
ber of detergents that
are commercially avail-
able, no single “univer-
sal detergent” is ideally
suited to all biochemi-
cal applications.
(G.G.Privé)
Non-ionic Detergents
6
C. Tanford
The hydrophobic effect: Formation
of micelles and biological mem-
branes.
Second edition.
John Wiley and Sons, New York
(1980)
U. Pfüller
Mizellen - Vesikel- Microemul-
sionen.
Tensidassoziate und ihre Anwend-
ung in Analytik und Biochemie.
Springer-Verlag, Berlin (1986)
H. Michel
Crystallization of membrane pro-
teins.
CRC Press Inc., Boca Raton (1991)
E.D. Goddard and K.P. Ananthapad-
man-anbhan, eds.
Interactions of surfactants with
polymers and proteins.
CRC Press Inc., Boca Raton (1993)
K. Holmberg, ed.
Novel surfactants: Preparation, ap-
plications and biodegradability.
Second edition.
Marcel Dekker Inc., New York (2003)
GENERAL REFERENCESM. Caffrey
Membrane protein crystallization.
J. Struct. Biol. 142, 108-132 (2003)
M.C. Wiener
A pedestrian guide to membrane
protein crystallization.
Methods 34, 364-372 (2004)
D. Myers
Surfactants science and technology.
Third edition.
John Wiley and Sons, New York
(2006)
G.G. Privé
Detergents for the stabilization
and crystallization of membrane
proteins.
Methods 41, 388-397 (2007)
7
NON-IONIC DETERGENTS
Bilayers and Micelles.
Detergents are amphipathic molecules
that contain both polar and hydrophobic
groups. All detergents are character-
ized as containing a hydrophilic “head”
region and a hydrophobic “tail” region.
In contrast to purely polar or non-polar
molecules, amphipathic molecules
exhibit unique properties in water. Their
polar group forms hydrogen bonds with
water molecules, while the hydrocarbon
chains aggregate due to hydrophobic
interactions. These properties allow de-
tergents to be soluble in water and also
to solubilize hydrophobic compounds in
aqueous systems.
Non-ionic Detergents
8
ALKYL GLYCOSIDES
MEGA-8
(Octanoyl-N-methylglucamide)
P-1060
MEGA-9
(Nonanoyl-N-methylglucamide)
P-1165
MEGA-10
(Decanoyl-N-methylglucamide)
P-1000
MEGA-12
(Dodecanoyl-N-methylglucamide)
P-1175
n-Nonyl β-D-glucopyranoside
(NGP)
P-1150
Octyl glucoside
(OGP)
P-1110
n-Dodecyl-β-D-maltoside
(DDM)
P-1170
N-D-GLUCO-N-METHYL-ALKANAMIDES(MEGAs)
NON-IONIC DETERGENTSAlkanoyl-N-methylglucamides combine a high solubilization power with non-denatur-
izing properties. They don’t interfere with the photometric monitoring of proteins at 280
nm (as their absorption maximum lies at 220 nm). Their easy removal by dialysis makes
them valuable tools for membrane studies. Like the alkanoyl-N-methylglucamides, the
alkylglucosides are mild detergents. Their CMC are only slightly affected by variations
of ionic strength. Oligoethyleneglycol monoalky ethers are standard detergents for the
solubilization and structural characterization of integral membrane proteins.
9
OLIGOETHYLENE-GLYCOL MONOALKYL ETHERS AND SULFOXIDES
Ethyleneglycolmonopentylether
(C5E
1; n-Pentylmonooxyethylene)
P-1055
Diethyleneglycolmonopentylether
(C5E
2; n-Pentyldioxyethylene)
P-1025
n-Pentyltrioxyethylene
(C5E
3; Triethyleneglycolmonopentyl
ether)
P-1135
n-Hexyltrioxyethylene
(C6E
3; Triethyleneglycolmonohexyl ether)
P-1095
n-Hexyltetraoxyethylene
(C6E
4; Tetraethyleneglycolmonohexyl
ether)
P-1085
n-Hexylpentaoxyethylene
(C6E
5; Pentaethyleneglycolmonohexyl
ether)
P-1080
n-Heptyltrioxyethylene
(C7E
3; Triethyleneglycolmonoheptyl
ether)
P-1075
n-Heptyltetraoxyethylene
(C7E
4; Tetraethyleneglycolmonoheptyl
ether)
P-1070
n-Heptylpentaoxyethylene
(C7E
5; Pentaethyleneglycolmonoheptyl
ether)
P-1065
Ethyleneglycolmonooctylether
(C8E
1; n-Octylmonooxyethylene)
P-1050
n-Octyltrioxyethylene
(C8E
3; Triethyleneglycolmonooctyl ether)
P-1125
n-Octyltetraoxyethylene
(C8E
4; Tetraethyleneglycolmonooctyl
ether)
P-1120
n-Octylpentaoxyethylene
(C8E
5; Pentaethyleneglycolmonooctyl
ether)
P-1115
n-Octylpolyoxyethylene
(C8E
n (n = 2 to 9); Octyl-POE;
Rosenbusch-Tenside)
P-1140
n-Decyltetraoxyethylene
(C10
E4; Tetraethyleneglycolmonodecyl
ether)
P-1010
n-Decylpentaoxyethylene
(C10
E5; Pentaethyleneglycolmonodecyl
ether)
P-1005
Dodecyl pentaethyleneglycolether
(C12
E5; Pentaethyleneglycolmonododecyl
ether)
P-1160
rac-2,3-Dihydroxypropyloctylsulfoxide
(n-Octyl-rac-2,3-dioxypropyl sulfoxide)
P-1040
2-Hydroxyethyloctylsulfoxide
(n-Octyl-2-hydroxyethyl sulfoxide)
P-1105
Non-ionic Detergents
10
Product
Number
Product CMC
(mM)
Conditions N (H2O) References
P-1060 MEGA-8 73 25°C F. Yu and R.E. McCarty, Arch. Biochem. Biophys. 238, 61 (1985)
P-1165 MEGA-9 25
50
25°C
15°C
V. de Pinto et al. , Eur. J. Biochem. 183, 179 (1989)
P-1000 MEGA-10 7 M. Hanatani et al., J. Biochem. 95, 1349 (1984)
P-1175 MEGA-12 0.35 25°C Y.-P. Zhu et al., J. Surf. Det. 2, 357 (1999)
P-1150 n-Nonyl β-D-glucopyranoside
6.5
3.5
7.5
low ionic strength
1M NaCl
25°C
133 W.J. de Grip and P.H.M. Bovee-Geurts, Chem. Phys Lipids 23, 321 (1979)
F. Yu and R.E. McCarty, Arch. Biochem. Biophys. 238, 61 (1985)
P-1110 Octyl glucoside 23.2
13.5
25.0
low ionic strength
1M NaCl
25°C
8427-100
W.J. de Grip and P.H.M. Bovee-Geurts, Chem. Phys Lipids 23, 321 (1979)
K. Shinoda et al., Bull. Chem. Soc. Jpn. 34, 237 (1961)
P-1170 n-Dodecyl-β-D-maltoside
170 78-14998
W.J. de Grip, Methods Enzymol. 81, 256 (1982)J. Kern et al., Photosynth. Res. 84, 153 (2005)
P-1095 n-Hexyltrioxyeth-ylene
100 25°C P. Becher, Micelle formation in aqueous and nonaqueous solutions. In: Nonionic Surfactants, M.J. Schick, ed., Marcel Dekker Inc., New York, p. 478 (1967)P-1085 n-Hexyltetraoxyeth-
ylene90 20°C
P-1080 n-Hexylpentaoxyeth-ylene
90 20°C
P-1050 Ethyleneglycolmon-ooctyl ether
4.9 25°C
P-1125 n-Octyltrioxyeth-ylene
7.5 25°C
P-1120 n-Octyltetraoxyeth-ylene
12.4
3.6
6°C
60°C
82 M. Corti et al., Phys. Rev. Lett. 48, 1617 (1982)R.M. Garavito and J.P. Rosenbusch, Methods Enzymol. 125, 309 (1986)
P-1115 n-Octylpentaoxyeth-ylene
4.3 25°C M. Zulauf and J.P. Rosenbusch, J. Phys. Chem. 87, 856 (1983)
P-1140 n-Octylpolyoxyeth-ylene
6.6 R.M. Garavito and J.P. Rosenbusch, Methods Enzymol. 125, 309 (1986)
P-1010 n-Decyltetraoxyeth-ylene
0.98
0.68
10°C
25°C
53 ± 10 P. Becher, Micelle formation in aqueous and nonaqueous solutions. In: Nonionic Surfactants, M.J. Schick, ed., Marcel Dekker Inc., New York, p. 478 (1967)
P-1005 n-Decylpentaoxyeth-ylene
1.18
0.81
10°C
25°C
73
P-1105 2-Hydroxyethyloctyl sulfoxide
29.9 R.M. Garavito and J.P. Rosenbusch, Methods Enzymol. 125, 309 (1986)
CALCITONINGENE-RELATEDPEPTIDES
ANTIMICROBIALPEPTIDES
AMYLOID PEPTIDES
CASPASESUBSTRATES INHIBITORS
CYSTEINEDERIVATIVES
GHRELIN,LEPTIN ANDOBESTATIN
1
DAP AND DABDERIVATIVES
ENDOTHELINS
1
FRET SUBSTRATES
DIABETES PEPTIDES
PEPTIDES IN COSMETICS
PARACTIVATINGPEPTIDES
NON-IONIC DETERGENTS
ORTHOGONALITYOF PROTECTINGGROUPS
PEPTIDE YY
VETERINARYPEPTIDES
PRIONPEPTIDES
PSEUDOPROLINEDIPEPTIDES
SECRETASESUBSTRATES INHIBITORS
VIP/PACAP
MATRIXMETALLO-PROTEINASES
LHRHAGONISTS AND ANTAGONISTS
MELANOMA PEPTIDES
NEUROPEPTIDE YN-METHYLATEDAMINO ACIDDERIVATIVES
PRODUCT BROCHURES
2006
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pub
lishe
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Gro
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016
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All information is compiled to the best of our knowledge. We cannot be made liable for any possible errors or misprints. Some products may be restricted in certain countries.
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