Amino Acids, Peptides, and Proteins Vocabulary

Vocabulary flashcards covering fundamental concepts, amino acid characteristics, protein purification techniques, and structural analysis methods from Chapter 3.

Primary Structure

The linear sequence of amino acids joined together by covalent amide linkages known as peptide bonds.

Isoelectric Point (pI)

The specific pH at which an amino acid or protein carries a net electric charge of zero.

Peptide Bond

A covalent amide linkage formed through a condensation reaction that connects amino acids in a linear chain.

Zwitterion

A dipolar molecule containing both positively and negatively charged functional groups, resulting in net zero electric charge at neutral pH.

Multisubunit Protein

A complex protein composed of two or more polypeptide chains associated noncovalently.

Oligomeric Protein

A multisubunit protein in which at least two of the associated polypeptide chains or subunits are identical.

Protomer

An identical subunit or repeating structural unit within an oligomeric protein.

Conjugated Protein

A protein containing permanently associated non-amino acid chemical components.

Prosthetic Group

The non-amino acid chemical component permanently attached to a conjugated protein.

Fractionation

The procedure of separating crude cellular extract into distinct fractions based on physical and chemical properties like size or charge.

Salting Out

A protein fractionation technique that selectively precipitates proteins by lowering their solubility in high concentrations of salt.

Dialysis

A separation procedure that utilizes a semipermeable membrane to separate large protein molecules from smaller solute particles.

Size-Exclusion Chromatography

A column chromatography technique, also known as gel filtration, that separates proteins based on size, allowing larger proteins to elute before smaller ones.

Ion-Exchange Chromatography

A column chromatography technique that separates proteins based on the sign and magnitude of their net electric charge.

Affinity Chromatography

A protein purification method that separates proteins based on their selective binding affinity for a ligand immobilized on a solid matrix.

High-Performance Liquid Chromatography (HPLC)

A chromatography technique that employs high-pressure pumps to move solvents through columns, significantly improving chromatographic resolution.

Sodium Dodecyl Sulfate (SDS)

An anionic detergent that binds to and partially unfolds proteins, conferring a uniform negative charge-to-mass ratio to enable molecular weight determination via electrophoresis.

Activity

The total units of enzyme activity present in a given sample solution.

Specific Activity

The ratio of enzyme activity units to the total mass of protein in milligrams, reflecting the purity of an enzyme preparation.

Polymorphic

Refers to proteins within a population that exhibit natural variants in their amino acid sequence without compromising essential function.

Edman Degradation

A classical biochemical procedure used to sequence peptides by removing and identifying one N-terminal amino acid residue at a time.

Proteases

Enzymes that catalyze the hydrolytic cleavage of peptide bonds within proteins.

Consensus Sequence

A representative sequence derived by identifying the most frequently occurring amino acid residue at each position in a set of aligned homologous proteins.

Homologs

Proteins belonging to the same protein family that share structural, functional, and evolutionary relationships.

Paralogs

Homologous proteins present within the same species that have evolved distinct functions following gene duplication.

Orthologs

Homologous proteins found in different species that perform equivalent biological functions.

Horizontal Gene Transfer

The direct transfer of genetic material between different organisms rather than through vertical descent from parent to offspring.

Signature Sequences

Specific short amino acid sequences or structural motifs that are unique to a particular taxonomic group.