Protein Folding
Protein folding is the physical process by which a linear polypeptide chain acquires its unique three-dimensional functional conformation, driven primarily by the hydrophobic effect, hydrogen bonding, electrostatic interactions, and van der Waals forces. The native folded state represents the lowest free-energy conformation under physiological conditions, as proposed by Christian Anfinsen's thermodynamic hypothesis (1972). Misfolding is linked to diseases such as Alzheimer's, Parkinson's, and prion diseases; understanding folding is therefore critical for drug design and therapeutic protein engineering.
Levels of Protein Structure
| Structure Level | Description | Stabilising Forces | Example |
|---|---|---|---|
| Primary | Linear amino acid sequence | Covalent peptide bonds | Gly-Ala-Val-... chain |
| Secondary | Local folding (α-helix, β-sheet) | Hydrogen bonds (backbone) | α-helix in haemoglobin |
| Tertiary | Overall 3D fold of single chain | Hydrophobic, disulfide, H-bonds, ionic | Myoglobin globular fold |
| Quaternary | Assembly of multiple subunits | Same as tertiary + subunit interfaces | Haemoglobin (2α + 2β) |
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Related Terms
Proteomics
Proteomics is the large-scale study of the entire complement of proteins (the proteome) expressed by a genome, cell, tissue, or organism at a given time and under specific conditions. Unlike the static genome, the proteome is highly dynamic — proteins vary in abundance, post-translational modifications (PTMs), localisation, and interactions in response to cellular state and environment. Mass spectrometry combined with two-dimensional gel electrophoresis or liquid chromatography is the primary technology platform used to identify, quantify, and characterise proteins at a systems level.
Bioinformatics
Bioinformatics is an interdisciplinary field that develops and applies computational methods, algorithms, and software tools to analyse and interpret large-scale biological data, particularly sequences of DNA, RNA, and proteins. It integrates biology, computer science, mathematics, and statistics to address problems such as genome assembly, sequence alignment, phylogenetic analysis, and structural prediction. The field is indispensable for modern genomics, drug discovery, and personalised medicine.
From Old English "fealdan" (to fold). The concept of spontaneous folding to a unique native state was established through Anfinsen's ribonuclease renaturation experiments, earning him the 1972 Nobel Prize in Chemistry.