Electrophoresis Theory and Methods

Vocabulary flashcards covering key terms, mathematical relations, and reagents involved in electrophoresis theory and methods from BCHEM 264 Lecture 4.

Electrophoresis

The motion of charged particles in a colloid under the influence of an electric field.

Ferdinand Friedrich Reuss

The scientist who observed electrophoresis for the first time in 1807, finding that a constant electric field caused clay particles in water to migrate at speeds depending on their size.

Vertical Gel Systems

Electrophoresis apparatus routinely used for protein separation on polyacrylamide gels.

Horizontal Gel Systems

Electrophoresis apparatus used for DNA separation on agarose gels.

Electric Gradient ($E$)

The applied voltage ($V$) divided by the distance ($d$) between electrodes, given by $E = \frac{V}{d}$.

Driving Force ($Eq$)

The force in newtons driving a charged particle toward an electrode in an electric gradient ($E$), where $q$ is charge in coulombs.

Velocity ($v$)

The migration speed of a charged particle in an electric field, defined as $v = \frac{Eq}{f}$, where $f$ is the frictional coefficient.

Electrophoretic Mobility ($\mu$)

The ratio of the velocity of a charged particle ($v$) to the electric field strength ($E$), expressed as $\mu = \frac{v}{E}$.

Ohm's Law

The equation expressing the relationship between voltage ($V$), current ($I$), and resistance ($R$), defined as $V = IR$.

Power ($W$)

The electric power generated in the support medium during electrophoresis, given by $W = I^2 R$, most of which is dissipated as heat.

Electroendosmosis (EEO)

The movement of liquid toward the cathode during electrophoresis, caused by immobilized anionic groups in the gel matrix and moving counter cations.

Silanol Groups

$\text{Si-OH}$ groups on glass capillary surfaces that ionize above $\text{pH } 3$ to form an electrical double layer, producing electroosmotic flow toward the cathode.

Arne Tiselius

The researcher who performed pioneering work on electrophoresis in free solution in 1930.

Agarose

A linear polysaccharide isolated from seaweeds with an average molecular mass of $12,000\,\text{Daltons}$, composed of repeating agarobiose units.

Agarobiose

The basic repeating unit of agarose, consisting of alternating 1,3-linked $\beta\text{-D-galactose}$ and 1,4-linked 3,6-anhydro-$\alpha\text{-L-galactose}$.

TAE Buffer

A Tris-Acetate-EDTA buffer solution used to prepare agarose gels.

PAGE

An acronym for Polyacrylamide Gel Electrophoresis.

Acrylamide

A monomer with formula $\text{C}_3\text{H}_5\text{NO}$ and molar mass $71.08\,\text{g/mol}$, existing as a white odorless crystalline solid that acts as a known neurotoxin and suspected carcinogen.

Bis-acrylamide

$N,N'$\text{-methylene-bis-acrylamide}, a cross-linking reagent with formula $\text{C}_7\text{H}_{10}\text{N}_2\text{O}_2$ and molar mass $154.17\,\text{g/mol}$ used in polyacrylamide gel preparation.

Ammonium Persulfate

An initiator reagent with formula $(\text{NH}_4)_2\text{S}_2\text{O}_8$ and molar mass $228.2\,\text{g/mol}$ that generates sulfate free radicals ($\text{SO}_4^{\bullet-}$) to begin acrylamide polymerization.

TEMED

$N,N,N',N'$\text{-tetramethylenediamine}, a catalyst that enhances free radical production from persulfate to promote polyacrylamide polymerization.

$$\%T$$

The total monomer concentration of acrylamide plus bis-acrylamide expressed in $\text{g}/100\,\text{ml}$.

$$\%C$$

The concentration of bis-acrylamide cross-linker expressed as a percentage of total monomer ($\%T$).

Riboflavin Photopolymerization

A gel polymerization process replacing persulfate and TEMED with riboflavin, which forms free radicals under bright light over 2-3 hours and is used for low-pH gels.