Hydrophobic effect in the context of "Lipid metabolism"

In chemistry, a non-covalent interaction differs from a covalent bond in that it does not involve the sharing of electrons, but rather involves more dispersed variations of electromagnetic interactions between molecules or within a molecule. The chemical energy released in the formation of non-covalent interactions is typically on the order of 1–5 kcal/mol (1000–5000 calories per 6.02×10 molecules). Non-covalent interactions can be classified into different categories, such as electrostatic, π-effects, van der Waals forces, and hydrophobic effects.

Non-covalent interactions are critical in maintaining the three-dimensional structure of large molecules, such as proteins and nucleic acids. They are also involved in many biological processes in which large molecules bind specifically but transiently to one another (see the properties section of the DNA page). These interactions also heavily influence drug design, crystallinity and design of materials, particularly for self-assembly, and, in general, the synthesis of many organic molecules.

Durable water repellent, or DWR, is a coating added to fabrics at the factory to make them water-resistant (hydrophobic). Most factory-applied treatments are fluoropolymer based; these applications are quite thin and not always effective. Durable water repellents are commonly used in conjunction with waterproof breathable fabrics such as Gore-Tex to prevent the outer layer of fabric from becoming saturated with water. This saturation, called 'wetting out,' can reduce the garment's breathability (moisture transport through the breathable membrane) and let water through. As the DWR wears off over time, re-treatment is recommended when necessary. Many spray-on and wash-in products for treatment of non-waterproof garments and re-treatment of proofed garments losing their water-repellency are available.

Methods for factory application of DWR treatments involve applying a solution of a chemical onto the surface of the fabric by spraying or dipping, or chemical vapor deposition (CVD). The advantages of CVD include reducing the use of environmentally harmful solvents; requiring less DWR; and an extremely thin waterproof layer that has less effect on the natural look and feel of the fabric.

Supramolecular chemistry is the branch of chemistry concerning chemical systems composed of discrete numbers of molecules. The strength of the forces responsible for spatial organization of the system ranges from weak intermolecular forces, electrostatic charge, or hydrogen bonding to strong covalent bonding, provided that the electronic coupling strength remains small relative to the energy parameters of the component. While traditional chemistry concentrates on the covalent bond, supramolecular chemistry examines the weaker and reversible non-covalent interactions between molecules. These forces include hydrogen bonding, metal coordination, hydrophobic forces, van der Waals forces, pi–pi interactions and electrostatic effects.

Important concepts advanced by supramolecular chemistry include molecular self-assembly, molecular folding, molecular recognition, host–guest chemistry, mechanically-interlocked molecular architectures, and dynamic covalent chemistry. The study of non-covalent interactions is crucial to understanding many biological processes that rely on these forces for structure and function. Biological systems are often the inspiration for supramolecular research.

In molecular biology, protein aggregation is a phenomenon in which intrinsically-disordered or mis-folded proteins aggregate (i.e., accumulate and clump together) either intra- or extracellularly. Protein aggregates have been implicated in a wide variety of diseases known as amyloidoses, including ALS, Alzheimer's, Parkinson's and prion disease.

After synthesis, proteins typically fold into a particular three-dimensional conformation that is the most thermodynamically favorable: their native state. This folding process is driven by the hydrophobic effect: a tendency for hydrophobic (water-fearing) portions of the protein to shield themselves from the hydrophilic (water-loving) environment of the cell by burying into the interior of the protein. Thus, the exterior of a protein is typically hydrophilic, whereas the interior is typically hydrophobic.

In chemistry, folding is the process by which a molecule assumes its shape or conformation. The process can also be described as intramolecular self-assembly, a type of molecular self-assembly, where the molecule is directed to form a specific shape through noncovalent interactions, such as hydrogen bonding, metal coordination, hydrophobic forces, van der Waals forces, pi-pi interactions, and electrostatic effects.

The most active area of interest in the folding of molecules is the process of protein folding, which analyses the specific sequences of amino acids in a protein. The shape of the folded protein can be used to understand its function and design drugs to influence the processes that it is involved in.

In supramolecular chemistry, host–guest chemistry describes complexes that are composed of two or more molecules or ions that are held together in unique structural relationships by forces other than those of full covalent bonds. Host–guest chemistry encompasses the idea of molecular recognition and interactions through non-covalent bonding. Non-covalent bonding is critical in maintaining the 3D structure of large molecules, such as proteins, and is involved in many biological processes in which large molecules bind specifically but transiently to one another.

Although non-covalent interactions could be roughly divided into those with more electrostatic or dispersive contributions, there are few commonly mentioned types of non-covalent interactions: ionic bonding, hydrogen bonding, van der Waals forces and hydrophobic interactions.

Protein–protein interactions (PPIs) are physical contacts of high specificity established between two or more protein molecules as a result of biochemical events steered by interactions that include electrostatic forces, hydrogen bonding and the hydrophobic effect. Many are physical contacts with molecular associations between chains that occur in a cell or in a living organism in a specific biomolecular context.

Proteins rarely act alone as their functions tend to be regulated. Many molecular processes within a cell are carried out by molecular machines that are built from numerous protein components organized by their PPIs. These physiological interactions make up the so-called interactomics of the organism, while aberrant PPIs are the basis of multiple aggregation-related diseases, such as Creutzfeldt–Jakob and Alzheimer's diseases.