Aging Effects on Protein Structure & Function

Vocabulary flashcards covering key terms related to how aging alters protein structure, folding, and homeostasis.

Protein Folding

The process by which a polypeptide chain adopts a specific three-dimensional structure required for its biological activity.

Chaperone Proteins

Helper proteins (e.g., HSP60, HSP70, protein-disulfide isomerases) that guide or stabilize the folding of other proteins.

Heat Shock Proteins (HSPs)

A subgroup of chaperones induced by cellular stress; key examples include HSP60 and HSP70.

Metastable Proteins

Proteins that can easily lose their correct conformation and become misfolded under stress or aging conditions.

Proteasome

A multi-enzyme complex that degrades ubiquitin-tagged misfolded or damaged proteins.

Ubiquitin–Proteasomal System

Pathway in which ubiquitin labels faulty proteins for destruction by the proteasome.

Proteostasis

Cellular homeostasis that balances protein folding by chaperones with degradation of misfolded proteins.

Protein Aggregation

Clumping of misfolded proteins; increases with aging and is linked to pathologies like AD and PD.

Reactive Oxygen Species (ROS)

Highly reactive molecules that accumulate with age and oxidatively damage proteins.

Protein Oxidation

Chemical modification of amino acids by ROS, leading to altered structure or function.

Disulfide Bonds

Covalent S–S links between cysteine residues that stabilize protein structure; vulnerable to age-related disruption.

Disulfide Cross-Links

Abnormal covalent links between proteins or within a protein formed during oxidative stress, promoting aggregation.

Carbonylation

Addition of carbonyl groups to amino acid side chains, a hallmark of oxidative protein damage.

Dityrosine Cross-Links

Covalent bonds between tyrosine residues formed under oxidative conditions, contributing to protein rigidity.

Methionine Sulfoxide

Oxidized form of methionine commonly detected in aged proteins.

Posttranslational Modification (PTM)

Chemical alteration of a protein after translation that affects folding, location, or activity.

Phosphorylation

Addition of phosphate groups (to Ser/Thr/Tyr) by kinases; dysregulation during aging disrupts signaling and folding.

Deamidation

Conversion of asparagine or glutamine to acidic residues, altering charge and destabilizing proteins (e.g., lens crystallins).

Methylation (Protein)

Addition of methyl groups to residues such as arginine or lysine, increasing hydrophobicity and misfolding risk.

Protein Disulfide Isomerase (PDI)

Enzyme that reshuffles disulfide bonds to aid correct protein folding.

Misfolded Proteins

Non-functional or toxic conformers that have escaped chaperone assistance.

Aging-Induced Proteostasis Imbalance

Age-related decline in chaperone activity and proteasomal degradation, tipping the balance toward aggregation.

Protein Cross-Links

Irreversible covalent bonds between proteins formed under oxidative stress, hindering degradation.

Alzheimer’s Disease (AD)

Neurodegenerative disorder linked to age-related protein aggregation (e.g., amyloid-β, tau).

Parkinson’s Disease (PD)

Neurodegenerative disease marked by aggregation of misfolded α-synuclein; associated with impaired proteostasis.