Hydrophobic collapse

Hydrophobic collapse is a proposed process for the production of the 3-D conformation adopted by polypeptides in polar solvents. The theory states that the nascent polypeptide forms initial secondary structure (ɑ-helices and β-strands) creating localized regions of predominantly hydrophobic residues. The polypeptide interacts with water, thus placing thermodynamic pressures on these regions which then aggregate or "collapse" into a tertiary conformation with a hydrophobic core. Incidentally, polar residues interact favourably with water, thus the solvent-facing surface of the peptide is usually composed of predominantly hydrophilic regions.

Partial hydrophobic collapse is an experimentally accepted model for the folding kinetics of many globular proteins, such as myoglobin,alpha-lactalbumin,barstar, and staphylococcal nuclease. However, because experimental evidence of early folding events is difficult to obtain, hydrophobic collapse is often studied in silico via molecular dynamics and Monte Carlo simulations of the folding process. Globular proteins that are thought to fold by hydrophobic collapse are particularly amenable to complementary computational and experimental study using phi value analysis.

Correct protein folding is integral to proper functionality within biological systems. Hydrophobic collapse is one of the main events necessary for reaching a proteins stable and functional conformation. Proteins perform extremely specific functions which are dependent on their structure. Proteins that do not fold correctly are nonfunctional and contribute nothing to a biological system.

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