Proteins (/ˈproʊˌtiːnz/ or /ˈproʊti.ᵻnz/) are large biomolecules, or macromolecules, consisting of one or more long chains of amino acid residues. Proteins perform a vast array of functions within living organisms, including catalyzing metabolic reactions, DNA replication, responding to stimuli, and transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in protein folding into a specific three-dimensional structure that determines its activity.

A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than 20-30 residues, are rarely considered to be proteins and are commonly called peptides, or sometimes oligopeptides. The individual amino acid residues are bonded together by peptide bonds and adjacent amino acid residues. The sequence of amino acid residues in a protein is defined by the sequence of a gene, which is encoded in the genetic code. In general, the genetic code specifies 20 standard amino acids; however, in certain organisms the genetic code can include selenocysteine and—in certain archaea—pyrrolysine. Shortly after or even during synthesis, the residues in a protein are often chemically modified by posttranslational modification, which alters the physical and chemical properties, folding, stability, activity, and ultimately, the function of the proteins. Sometimes proteins have non-peptide groups attached, which can be called prosthetic groups or cofactors. Proteins can also work together to achieve a particular function, and they often associate to form stable protein complexes.

Proteins : Structure, Function, and Bioinformatics is a monthly peer-reviewed scientific journal published by John Wiley & Sons, which was established in 1986 by Cyrus Levinthal. The journal covers research on all aspects protein biochemistry, including computation, function, structure, design, and genetics. The editor-in-chief is Bertrand Garcia-Moreno (Johns Hopkins University).

Publishing formats are original research reports, short communications, prediction reports, invited reviews, and topic proposals. In addition, Proteins includes a section entitled "Section Notes", describing novel protein structures.

Abstracting and indexing

Proteins is abstracted and indexed in:

According to the Journal Citation Reports, the journal has a 2011 impact factor of 3.392.

Proteins are present in wine. The most common proteins include thaumatin-like proteins and chitinases and have a role in the formation of turbidity (haze) especially visible in white wine. The quantity of haze forming is dependent on the quantity of phenolics in the wine.

Some of those proteins are considered nuisance. Some of them are grape pathogenesis-related proteins. Those proteins have been identified by mass spectrometry and originate from grape, yeast, bacteria and fungi.

These proteins are unstable when submitted to heat but can be removed with treatment with bentonite, process called clarification and stabilization of wine.

Proteins residues from proteinaceous fining agents such as gelatin or egg white can possibly be found in wine. Wheat gluten has also been tested but there are health issues regarding its use because of gluten intolerance in some people.

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