Globular Proteins: Tertiary and Quaternary Structure

These flashcards cover key vocabulary and concepts related to globular proteins' tertiary and quaternary structures, as discussed in the lecture.

Tertiary structure

Overall three-dimensional arrangement of all the atoms in a protein.

Quaternary structure

Arrangement of 2 or more separate polypeptide chains in three-dimensional complexes.

Domains

Compact units of protein structure that are independently stable.

Motifs

Recognizable folding patterns involving 2 or more elements of secondary structures.

Intrinsic disorder

Regions in proteins that lack a defined structure and often interact with multiple binding partners.

Cryoelectron microscopy

A newer method used to visualize the structure of proteins.

X-ray crystallography

Traditional method used to determine the atomic structure of proteins.

Nuclear Magnetic Resonance (NMR)

Traditional method that provides information about protein structure in solution.

Heterodimer

A protein complex made of two different polypeptide chains.

Homodimer

A protein complex made of two identical polypeptide chains.

Oligomer

A protein composed of multiple polypeptide chains or subunits.

Subunit

One polypeptide chain in a protein made up of more than one chain.

Prosthetic groups

Permanently associated chemical components in conjugated proteins.

Conjugated proteins

Proteins that contain additional components beyond amino acids.

Myoglobin

A protein that binds oxygen; the first atomic resolution protein structure solved.

Beta-mercaptoethanol

Chemical that breaks disulfide bonds in proteins.

Urea

Chemical that disrupts non-covalent interactions in proteins.

Protein Data Bank (PDB)

Archive of experimentally determined three-dimensional structures of proteins.

Multisubunit proteins

Proteins composed of more than one polypeptide chain.

G protein

A protein that hydrolyzes GTP to GDP.

Beta-α-beta loop

A simple protein motif connecting secondary structures.

Flavoproteins

Proteins that contain flavin nucleotides as prosthetic groups.

Metalloproteins

Proteins that contain metal ions as part of their structure.

Tetramers

Proteins made up of four polypeptide chains.

Disulfide bonds

Covalent bonds that can stabilize protein structure.

Regulatory proteins

Proteins involved in controlling biological processes.

Transport proteins

Proteins that carry substances across cell membranes.

Motor proteins

Proteins that facilitate movement in cells.

Immunoglobulins

Antibody proteins that play a key role in immune response.

Structural diversity

The variety in protein structures that allows for different functions.

Weak interactions

Interactions that stabilize tertiary structure, including hydrogen bonds and van der Waals forces.

Domains vs Motifs

Domains are stable units of structure; motifs are recognizable patterns.

Sigmoid curve

Type of binding curve often seen in allosteric proteins such as hemoglobin.

Glutamine

An amino acid commonly involved in hydrogen bonding.

Thermal denaturation

Process where high temperatures disrupt protein structure.

Affinity chromatography

Method for purifying proteins based on specific interactions.

Intrinsic disorder in proteins

Feature allowing proteins to adapt to multiple biological functions.

Hydrophilic residues

Amino acids that are attracted to water, usually on the exterior of proteins.

Hydrophobic residues

Amino acids that repel water, usually found in the protein core.

Foam formation

A phenomenon where proteins can stabilize air bubbles by forming a network.

Alpha-helix

A common structural motif in proteins formed by coiling of polypeptide chains.

Beta-sheet

A secondary structure formed by hydrogen bonds between chains of protein.

Protein folding

Process through which a polypeptide folds into its three-dimensional structure.

Structural representation

Graphical depiction of a protein's three-dimensional structure.

Test for oligomeric structure

Analyzing protein sizes post-treatment with disruptors like urea.

Conditional study

Research to observe protein behavior under different scenarios.

RfaH

A bacterial transcription factor that is a metamorphic protein.

Statistical analysis

Technique used to interpret data from protein studies.

AlphaFold

AI-based tool used to predict protein structures.

Multidomain proteins

Proteins that consist of multiple distinct functional domains.

Transcription factors

Proteins that regulate gene expression.

PDB ID

Unique identifier assigned to protein structures in the Protein Data Bank.

Covalent bonds

Strong chemical bonds that can stabilize protein shape.