Protein Laboratory

Each list begins with basic conceptual vocabulary you need to know for MCAT questions and proceeds to advanced terms that might appear in context in MCAT passages. The terms are links to Wikipedia articles.
Chromatography is the collective term for laboratory techniques which separate analytes dissolved in a mobile phase by passing them through a stationary phase.
Gel electrophoresis
Gel electrophoresis is a technique used for the separation of biological molecules using an electric field.
Centrifugation is a process that involves the use of the centripetal force for the separation of mixtures.
Western blot
The western blot (sometimes called the protein immunoblot) is a widely used analytical technique in molecular biology and immunogenetics to detect specific proteins in a sample of tissue homogenate or extract.
SDS-PAGE, officially sodium dodecyl sulfate polyacrylamide gel electrophoresis, is a technique used to separate proteins according to their electrophoretic mobility.
Thin layer chromatography
Thin layer chromatography is a chromatography technique involving a stationary phase consisting of a thin patina of adsorbent material immobilised on a flat, inert carrier sheet.
Dialysis is the process of separating molecules in solution by the difference in their rates of diffusion through a semipermeable membrane.
Supernate refers to the liquid or clear fluid above a sediment or precipitate.
Size-exclusion chromatography
Size-exclusion chromatography, also known as gel-filtration chromatography chromatography, is a chromatographic method in which molecules in solution are separated by their size, and in some cases molecular weight.
Affinity chromatography
Affinity chromatography is a method of separating a biomolecule from a mixture, based on a highly specific macromolecular binding interaction between the biomolecule and another substance.
In analytical and organic chemistry, elution is the process of extracting one material from another by washing with a solvent; as in washing of loaded ion-exchange resins to remove captured ions.
Spectrophotometry is a branch of electromagnetic spectroscopy concerned with the quantitative measurement of the reflection or transmission properties of a material as a function of wavelength.
Monoclonal antibody
A monoclonal antibody is an antibody made by cloning a unique white blood cell.
Ion-exchange chromatography
Ion-exchange chromatography separates molecules based on their respective charged groups.
Immunostaining is a general term in biochemistry that applies to any use of an antibody-based method to detect a specific protein in a sample.
Fractionation is a separation process in which a certain quantity of a mixture is divided up in a large number of smaller quantities in which the composition changes according to a gradient.
Enzyme-linked immunosorbent assay (ELISA)
The enzyme-linked immunosorbent assay uses a solid-phase type of enzyme immunoassay to detect the presence of a ligand (commonly a protein) in a liquid sample using antibodies directed against the protein to be measured.
Salting out
Salting out is the most common method used to precipitate a protein.
Retardation factor
In planar chromatography the retardation factor is defined as the ratio of the distance traveled by the center of a spot to the distance traveled by the solvent front.
A fluorophore is a fluorescent chemical compound that can re-emit light upon light excitation.
Edman degradation
Edman degradation is a method of sequencing amino acids in a peptide in which the amino-terminal residue is labeled and cleaved from the peptide without disrupting the peptide bonds between other amino acid residues.
2-Mercaptoethanol is used to reduce disulfide bonds and can act as a biological antioxidant by scavenging hydroxyl radicals.
Isoelectric focusing
Isoelectric focusing is a technique for separating different molecules by differences in their isoelectric point.
High-performance liquid chromatography (HPLC)
High-performance liquid chromatography relies on pumps to pass a pressurized liquid solvent containing the sample mixture through a column filled with a solid adsorbent material.
A Svedberg unit (symbol S) is a non-SI metric unit for sedimentation coefficients.
Peptide mass fingerprinting
Peptide mass fingerprinting is an analytical technique for protein identification in which the unknown protein of interest is first cleaved into smaller peptides, whose absolute masses can be accurately measured with a mass spectrometer.
Fusion proteins
Fusion proteins or chimeric proteins are proteins created through the joining of two or more genes that originally coded for separate proteins.
Immunoprecipitation is the technique of precipitating a protein antigen out of solution using an antibody that specifically binds to that particular protein.
A polyhistidine-tag is an amino acid motif in proteins that typically consists of at least six histidine residues, often at the N- or C-terminus of the protein, making it possible to separate the protein by chromatography due to the affinity of histidine for metal ions.
Often used in chromatography resin, streptavidin is a protein purified from the bacterium Streptomyces avidinii that has an extraordinarily high affinity for biotin
Circular dichroism spectroscopy
Circular dichroism spectroscopy employs circularly polarized light to investigates the secondary structure of proteins by means of the differential absorption of left- and right-handed light.
Matrix-assisted laser desorption/ionization (MALDI)
In mass spectrometry, matrix-assisted laser desorption/ionization (MALDI) is an ionization technique that uses a laser energy absorbing matrix to create ions from large molecules with minimal fragmentation.
Protein microarray
A protein microarray is a piece of glass on which different molecules of protein have been affixed at separate locations in an ordered manner thus forming a microscopic array.
Secondary antibody
A secondary antibody is an antibody that binds to a primary antibody usually as part of a detection, purification or cell sorting application.
Silica gel
Silica gel is a granular, porous form of silica which is often used in chromatography as a stationary phase.
Differential centrifugation
Differential centrifugation is a procedure in which a homogenate is subjected to repeated centrifugations in which, after each time, the pellet is removed and the centrifugal force is increased.
Southwestern blot
Southwestern blotting, based along the lines of Southern blotting, involves characterizing proteins that bind to DNA.
Van Deemter's equation
Van Deemter's equation in chromatography relates the variance per unit length of a separation column to the linear mobile phase velocity by considering physical, kinetic, and thermodynamic properties of a separation.
Aqueous normal phase chromatography
Aqueous normal phase chromatography is a chromatographic technique which encompasses the mobile phase region between reversed-phase chromatography and organic normal phase chromatography.
Tandem affinity purification (TAP)
Tandem affinity purification (TAP) is an immunoprecipitation-based purification technique for studying protein–protein interactions. The goal is to extract from a cell only the protein of interest, in complex with any other proteins it interacted with.
Displacement chromatography
Displacement chromatography is a chromatography technique in which a sample is placed onto the head of the column and is then displaced by a solute that is more strongly sorbed than the components of the original mixture.
Hofmeister series
The Hofmeister series or lyotropic series is a classification of ions in order of their ability to salt out or salt in proteins.

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