Detergents and Surf Act Ants 2010

8/3/2019 Detergents and Surf Act Ants 2010

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Detergents and Surfactants

Solubilization of membraneproteins


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Types of membrane proteins

Transmembrane proteins

Cytosolic membrane proteins

External membrane proteins

Peripheral membrane proteins


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Noncovalent association with the polar

ends of transmembrane proteins

Peripheral Membrane

Proteins


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Hydrophobic amino

acids in light green

& yellow


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Single-pass transmembrane

protein with an helix

transmembrane domain

Glycophorin


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Solubilization of membraneproteins

Transmembrane proteins are difficultto solubilize because of theirhydrophobicity Requires detergents

Small amphipathic molecules that formmicelles in water (Fig. 10-23)


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Solubilization of membrane proteins

Transmembrane proteins are difficult to

solubilize because of their hydrophobicity

Requires detergents

Small amphipathic molecules that form micelles in

water (Fig. 10-23)


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Cross section of a detergent micelle

SOLUBILIZATION

The hydrophobic ends of the detergent bind to thehydrophobic region of the transmembrane protein, thereby

displacing lipid molecules

Since the other end of the detergent molecule is polar,the protein isbrought into aqueous solution as a detergent-protein complex


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Detergent solubilization ofmembrane proteins


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Solubilization of membrane proteins

Transmembrane proteins are difficult tosolubilize because of their hydrophobicity Requires detergents

Small amphipathic molecules that form micelles inwater (Fig. 10-23)

By using detergents, transmembraneproteins can be solubilized and

reconstituted into liposomes Powerful means of analyzing their properties(Fig. 10-26)


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Na+- K+ pump solubilized & reconstituted intoliposome

(ion pump present on plasma membrane of moanimal cells uses ATP for energy)

Pumps Na+ out of the cell andK+ into the cell


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Detergents and Surfactants

Introduction:

Detergents are a class of molecules whose uniqueproperties enable manipulation (disruption or formation)of hydrophobic-hydrophilic interactions among moleculesin biological samples.

Although the cleansing action is similar, the detergentsdo not react as readily with hard water ions of calciumand magnesium.

Detergent molecular structures consist of a longhydrocarbon chain and a water soluble ionic group. Mostdetergents have a negative ionic group and are calledanionic detergents. The majority are alky sulfates.


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In biological research, detergents are used tolyse cells (release soluble proteins)

solubilize membrane proteins and lipids. prevent nonspecific binding in affinitypurification and immunoassay procedures, and

as additives in electrophoresis. Generally, moderate concentrations of mild

(nonionic) detergents compromise the integrityof cell membranes, thereby facilitating lysis ofcells and extraction of soluble protein, often innative form.

Using other conditions, detergents effectively

penetrate between the membrane bilayers atconcentrations suffi- cient to form mixedmicelles with isolated phospholipids andmembrane proteins.


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Cationic Detergents

Another class of detergents have a positive ionic

charge and are called "cationic" detergents. In addition to being good cleansing agents, they

also possess germicidal properties which makesthem useful in hospitals.

Most of these detergents are derivatives ofammonia.

A cationic detergent is most likely to be found in ashampoo or clothes "rinse".

The purpose is to neutralize the static electrical

charges from residual anionic (negative ions)detergent molecules. Since the negative chargesrepel each other, the positive cationic detergentneutralizes this charge.


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Neutral or non-ionic detergents:

Nonionic detergents are used in dish washing

liquids. Since the detergent does not have any ionic

groups, it does not react with hard water ions. The detergent molecules must have some polar

parts to provide the necessary water solubility. In the graphic on the left, the polar part of the

molecule consists of three alcohol groups andan ester group.

The non-polar part is the usual longhydrocarbon chain.


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Bile Salts - Intestinal Natural Detergents:

Bile acids are produced in the liver and secreted in the intestine

via the gall bladder. Bile acids are oxidation products of cholesterol. First the cholesterol is converted to the trihydroxy derivative

containing three alcohol groups. The end of the alkane chain at C# 17 is converted into an acid, and finally the amino acid, glycine

is bonded through an amide bond. The acid group on the glycineis converted to a salt.

The bile salt is called sodiumglycoholate. Another salt can bemade with a chemical called taurine.

The main function of bile salts is to act as a soap or detergent inthe digestive processes. The major action of a bile salt is toemulsify fats and oils into smaller droplets. The various enzymescan then break down the fats and oils.


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In a solubilization process, the detergent molecules bindwith their hydrophobic part to the hydrophobic region ofthe protein.

In this process they remove part of the phospholipids which

surround the protein in its natural environment.

Since the hydrophilic part of the detergent points awayfrom the protein and interacts with the watery milieu, withenough detergent bound, the protein may go into solution and if you are lucky it keeps its conformation.

Solubilised membrane proteins are therefore complexeswhich consist out of protein, detergent and remainingphospholipids.

The share of each component depends on the composition ofthe solubilisation buffer and the nature and concentration

of the detergent. Usually detergent and phospholipids make up 10-50% of

the complex.


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micelles

Detergents at low concentration in aqueous solution form amonolayer at the air-liquid interface.

At higher concentrations, detergent monomers aggregateinto structures called micelles (Figure 5).

A micelle is a thermodynamically stable colloidal aggregate

of detergent monomers where in the nonpolar ends aresequestered inward, avoiding exposure to water, and thepolar ends are oriented outward in contact with the water.

Both the number of detergent monomers per micelle(aggregation numberN)

and the range of detergent concentration above whichmicelles form (called the critical micelle concentration,CMC) are properties specific to each particular detergent.


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the critical micelle concentration,CMC)


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Detergent properties are affected byexperimental conditions such as concentration,temperature, buffer pH and ionic strength, and

the presence of various additives. For example, the CMC of certain nonionic

detergents decreases with increasingtemperature, while the CMC of ionic detergents

decreases with addition of counter ion as aresult of reduced electrostatic repulsion amongthe charged head groups.

In other cases, additives such as urea

effectively disrupt water structure and cause adecrease in detergent CMC. Generally, dramatic increases in aggregation

number occur with increasing ionic strength.


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In other cases, additives such as ureaeffectively disrupt water structure and

cause a decrease in detergent CMC.Generally, dramatic increases inaggregation number occur with increasingionic strength.


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Organic Chemistry

- Extraction of Analgesic Components

Extraction is apurification technique in which compounds

with different solubilities are separatedusing solvents of

different polarities. This basic chemical process is often

performed in conjunction with reversible acid/base reactions.


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Liquid-Liquid

Extraction

Requirements for a liquid-liquid extraction:

two immiscible liquidswith different

densities & different refractive indices

Recognize which layer is which (organic vs. aqueous phases)& understand which compounds are dissolved in each phase.

Why

separatory

funnel


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Liquid-Liquid Extraction

Immiscible non-mixing (i.e. oil and water)

Immiscible liquids have significantly different solubilities/polarities

which keep them from dissolving each other (in reality they are not

completely non-mixing, there is some carry over). Still they must

physically separate (density) and be visibly distinguishable (nD).

Common Immiscible Mixes

oil spill oil & water

salad dressing oil &

vinegar

ether extraction EtO2 &

water

Associated Terms

hydrophilic hydrophobic

polar nonpolar

water layer organic layer

aqueous phase organic phase

{aqueous base} {CH2Cl2 layer}

emulsion


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Extraction is a process that separates components based

upon chemical differences rather than differences in physical

properties.

The basic principle behind extraction involves the contacting

of a solution with another solvent that is immiscible with the

original.

The solvent is also soluble with a specific solute contained in

the solution.

.


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solvent extraction

Liquid extraction (or solvent extraction) refers to anoperation in which the components of a liquidmixture are separated by contacting it with a suitableinsoluble liquid solvent which preferentially dissolvesone or more components.

the separation of the components depends upon theunequal distribution of the components between theimmiscible liquids.

The feed solution represents one phase and thesolvent to be used to effect separation representsthe second phase.

The mass transfer of the solute liquid takes placefrom the feed solution to the solvent phase.


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Two phases are formed after the addition of the solvent, due to the

differences in densities.

The solvent is chosen so that the solute in the solution has moreaffinity toward the added solvent.

Therefore mass transfer of the solute from the solution to the

solvent occurs.The solution to be extracted is called the feed.

The liquid extraction liquid is called the solvent.

The residual liquid solution from which the solute is

removed is called the raffinate.The extracted solvent rich product is called the

extract.

The extract phase contains the desired product in a

larger proportion


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solution of acetic acid in water is contacted with a

solvent such as ethyl acetate then two phases will

results. The extract (ester/organic layer) will contain most of

acetic acid in ethyl acetate with a small amount

water.

The raffinate (aqueous layer) will contain a weak

acetic acid solution with a small amount of ethyl

acetate.

The amount of water in the extract and ethylacetate in the raffinate depends upon their

solubilties in one another.

Th Di t ib ti C ffi i t


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The Distribution Coefficient

In dilute solutions at equilibrium, theconcentration of the solute in the two

phases is called the distribution coefficient

or distribution constant K.

K= CE/CR

Where the CE and CR are the

concentrations of the solute in the extract

and the raffinate phases respectively.


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The Distribution Coefficient

The distribution coefficient can also be given

as the weight fraction of the solute in the two

phases in equilibrium contact:

K = y*/x

Where y* is the weight fraction of the solute in

the extract and x is the weight fraction of the

solute in the raffinate.


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Modes of Operation: Cross-Current

Cross-current mode is mostly used in batch

operation.

Batch extractors have traditionally been used

in low capacity, \multi-product plants typically

found in the pharmaceutical and agrochemical

industries.


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Osmosis

Osmosis is the spontaneous net movementof water across a semipermeable membranefrom a region of low solute concentration toa solution with a high solute concentration,

down a solute concentration gradient. It is a physical process in which a solvent

moves, without input of energy, across a semi

permeable membrane (permeable to thesolvent, but not the solute) separating twosolutions of different concentrations.
http://en.wikipedia.org/wiki/Semipermeable_membranehttp://en.wikipedia.org/wiki/Semipermeable_membrane


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Osmosis

Net movement of solvent is from the less-

concentrated (hypotonic)

to the more-concentrated (hypertonic)

solution,

which tends to reduce the difference in

concentrations.

This effect can be countered by increasing the

pressure of the hypertonic solution, with

respect to the hypotonic.
http://en.wikipedia.org/wiki/Hypotonichttp://en.wikipedia.org/wiki/Hypertonichttp://en.wikipedia.org/wiki/Hypertonichttp://en.wikipedia.org/wiki/Hypotonic


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osmotic pressure

The osmotic pressure is defined to be thepressure required to maintain an

equilibrium, with no net movement ofsolvent.

Osmotic pressure is a colligative property,meaning that the property depends on the

molar concentration of the solute but not onits identity.

Osmosis is the result ofdiffusion across a

semi-permeable membrane
http://en.wikipedia.org/wiki/Osmotic_pressurehttp://en.wikipedia.org/wiki/Osmotic_pressurehttp://en.wikipedia.org/wiki/Pressurehttp://en.wikipedia.org/wiki/Colligative_propertieshttp://en.wikipedia.org/wiki/Concentrationhttp://en.wikipedia.org/wiki/Diffusionhttp://en.wikipedia.org/wiki/Diffusionhttp://en.wikipedia.org/wiki/Concentrationhttp://en.wikipedia.org/wiki/Colligative_propertieshttp://en.wikipedia.org/wiki/Pressurehttp://en.wikipedia.org/wiki/Osmotic_pressurehttp://en.wikipedia.org/wiki/Osmotic_pressure


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Osmotic pressure

Diffusion of water across a membrane -osmosis - generates a pressure called

osmotic pressure. If the pressure in the compartment into

which water is flowing is raised to theequivalent of the osmotic pressure,

movement of water will stop. This pressure is often called hydrostatic

('water-stopping') pressure.

-The term osmolarity is used to describe the


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-The term osmolarity is used to describe the

number of solute particles in a volume of fluid.

Osmoles are used to describe the

concentration in terms of number of particles

a 1 osmolar solution contains 1 mole of

osmotically-active particles (molecules and

ions) per liter.

The classic demonstration of osmosis and

osmotic pressure is to immerse red blood cells

in solutions of varying osmolarity and watchwhat happens.


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The osmotic pressure of a dilute solution is

found to obey a relationship of the same form

as the ideal gas law:

it is usually expressed in terms of the molarity

of the solution and given the symbol p.
http://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/diffus.htmlhttp://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/idegas.htmlhttp://hyperphysics.phy-astr.gsu.edu/hbase/chemical/solution.htmlhttp://hyperphysics.phy-astr.gsu.edu/hbase/chemical/solution.htmlhttp://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/idegas.htmlhttp://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/diffus.html


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In chemistry texts, it is usually expressed in

terms of the molarity of the solution and given

the symbolp

.M is the molar concentration of dissolved species (units ofmol/L).

R is the ideal gas constant (0.08206 L atm mol-1 K-1, or other

values depending on the pressure units).

Tis the temperature on the Kelvin scale.

Osmotic Pressure in atm. = Molarity ( R ) (Kelvin Temp.)
http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/solution.htmlhttp://hyperphysics.phy-astr.gsu.edu/hbase/chemical/solution.html


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One of the goals here is to solidify the idea of describing solutions in terms of

molarity versus mass concentration (grams/liter). In the images below MW is

an abbreviation for molecular weight (grams per mole).

Example 1: Glucose is a monosaccharide and

sucrose (table sugar) is a disaccharide.
http://www.vivo.colostate.edu/hbooks/cmb/cells/pmemb/osmosis_eg.html


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Example 2: Same solutes as in Example 1, but

their concentrations are presented differently.
http://www.vivo.colostate.edu/hbooks/cmb/cells/pmemb/osmosis_eg.htmlhttp://www.vivo.colostate.edu/hbooks/cmb/cells/pmemb/osmosis_eg.htmlhttp://www.vivo.colostate.edu/hbooks/cmb/cells/pmemb/osmosis_eg.htmlhttp://www.vivo.colostate.edu/hbooks/cmb/cells/pmemb/osmosis_eg.html


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NaCl or sodium chloride is, of course, table

salt. Before doing the problem, think about

what happens to salt when it is dissolved in

water.
http://www.vivo.colostate.edu/hbooks/cmb/cells/pmemb/osmosis_eg.htmlhttp://www.vivo.colostate.edu/hbooks/cmb/cells/pmemb/osmosis_eg.htmlhttp://www.vivo.colostate.edu/hbooks/cmb/cells/pmemb/osmosis_eg.htmlhttp://www.vivo.colostate.edu/hbooks/cmb/cells/pmemb/osmosis_eg.htmlhttp://www.vivo.colostate.edu/hbooks/cmb/cells/pmemb/osmosis_eg.htmlhttp://www.vivo.colostate.edu/hbooks/cmb/cells/pmemb/osmosis_eg.html


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Example 4: Albumin is the most abundant

protein in blood. Glycine is an amino acid -

assume that it is not a salt.
http://www.vivo.colostate.edu/hbooks/cmb/cells/pmemb/osmosis_eg.htmlhttp://www.vivo.colostate.edu/hbooks/cmb/cells/pmemb/osmosis_eg.htmlhttp://www.vivo.colostate.edu/hbooks/cmb/cells/pmemb/osmosis_eg.htmlhttp://www.vivo.colostate.edu/hbooks/cmb/cells/pmemb/osmosis_eg.htmlhttp://www.vivo.colostate.edu/hbooks/cmb/cells/pmemb/osmosis_eg.htmlhttp://www.vivo.colostate.edu/hbooks/cmb/cells/pmemb/osmosis_eg.html


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Example 5:Insulin is a small protein

hormone that is critical for

maintaining normal blood glucose

concentrations.
http://www.vivo.colostate.edu/hbooks/cmb/cells/pmemb/osmosis_eg.htmlhttp://www.vivo.colostate.edu/hbooks/cmb/cells/pmemb/osmosis_eg.htmlhttp://www.vivo.colostate.edu/hbooks/pathphys/endocrine/pancreas/insulin.htmlhttp://www.vivo.colostate.edu/hbooks/pathphys/endocrine/pancreas/insulin.htmlhttp://www.vivo.colostate.edu/hbooks/cmb/cells/pmemb/osmosis_eg.html


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Example 6: KCl or potassium chloride is an

inorganic salt. For the first time, we see a

mixture of solutes in the right compartment.
http://www.vivo.colostate.edu/hbooks/cmb/cells/pmemb/osmosis_eg.html

Documents

Detergents and Surf Act Ants 2010