Protein

Proteins are large biomolecules, or macromolecules, consisting of one or more long chains of amino acid residues.

A macromolecule is a very large molecule, such as protein, commonly created by the polymerization of smaller subunits called monomers.

Proteins are large biomolecules, or macromolecules, consisting of one or more long chains of amino acid residues.

Biomolecules include large macromolecules (or polyanions) such as proteins, carbohydrates, lipids, and nucleic acids, as well as small molecules such as primary metabolites, secondary metabolites, and natural products.

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.

Protein folding is the physical process by which a protein chain acquires its native 3-dimensional structure, a conformation that is usually biologically functional, in an expeditious and reproducible manner.

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. 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 biology, a gene is a sequence of nucleotides in DNA or RNA that encodes the synthesis of a gene product, either RNA or protein.

The sequence of amino acid residues in a protein is defined by the sequence of a gene, which is encoded in the genetic code.

Protein primary structure is the linear sequence of amino acids in a peptide or protein.

Sometimes proteins have non-peptide groups attached, which can be called prosthetic groups or cofactors.

A cofactor is a non-protein chemical compound or metallic ion that is required for an enzyme's activity as a catalyst, a substance that increases the rate of a chemical reaction.

Once formed, proteins only exist for a certain period and are then degraded and recycled by the cell's machinery through the process of protein turnover.

Proteolysis is the breakdown of proteins into smaller polypeptides or amino acids.

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.

Pyrrolysine (symbol Pyl or O; encoded by the 'amber' stop codon UAG) is an α-amino acid that is used in the biosynthesis of proteins in some methanogenic archaea and bacteria; it is not present in humans.

Many proteins are enzymes that catalyse biochemical reactions and are vital to metabolism.

Enzymes are both proteins and biological catalysts (biocatalysts).

Proteins also have structural or mechanical functions, such as actin and myosin in muscle and the proteins in the cytoskeleton, which form a system of scaffolding that maintains cell shape.

Actin is a family of globular multi-functional proteins that form microfilaments.

Many proteins are enzymes that catalyse biochemical reactions and are vital to metabolism.

The three main purposes of metabolism are: the conversion of food to energy to run cellular processes; the conversion of food/fuel to building blocks for proteins, lipids, nucleic acids, and some carbohydrates; and the elimination of nitrogenous wastes.

Like other biological macromolecules such as polysaccharides and nucleic acids, proteins are essential parts of organisms and participate in virtually every process within cells.

Cells consist of cytoplasm enclosed within a membrane, which contains many biomolecules such as proteins and nucleic acids.

A linear chain of amino acid residues is called a polypeptide.

Peptides are distinguished from proteins on the basis of size, and as an arbitrary benchmark can be understood to contain approximately 50 or fewer amino acids.

Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells, and organisms, and transporting molecules from one location to another.

A number of proteins are associated with the replication fork to help in the initiation and continuation of DNA synthesis.

The sequence of amino acid residues in a protein is defined by the sequence of a gene, which is encoded in the genetic code.

DNA sequencing is also the most efficient way to indirectly sequence RNA or proteins (via their open reading frames).

Proteins may be purified from other cellular components using a variety of techniques such as ultracentrifugation, precipitation, electrophoresis, and chromatography; the advent of genetic engineering has made possible a number of methods to facilitate purification.

Protein purification is a series of processes intended to isolate one or a few proteins from a complex mixture, usually cells, tissues or whole organisms.

The individual amino acid residues are bonded together by peptide bonds and adjacent amino acid residues.

A peptide bond is an amide type of covalent chemical bond linking two consecutive alpha-amino acids from C1 (carbon number one) of one alpha-amino acid and N2 (nitrogen number two) of another along a peptide or protein chain.

Proteins can also work together to achieve a particular function, and they often associate to form stable protein complexes.

Protein complexes are a form of quaternary structure. Proteins in a protein complex are linked by non-covalent protein–protein interactions, and different protein complexes have different degrees of stability over time.

Methods commonly used to study protein structure and function include immunohistochemistry, site-directed mutagenesis, X-ray crystallography, nuclear magnetic resonance and mass spectrometry.

The method also revealed the structure and function of many biological molecules, including vitamins, drugs, proteins and nucleic acids such as DNA.

Most proteins consist of linear polymers built from series of up to 20 different L -α- amino acids.

Polymers range from familiar synthetic plastics such as polystyrene to natural biopolymers such as DNA and proteins that are fundamental to biological structure and function.

All proteinogenic amino acids possess common structural features, including an α-carbon to which an amino group, a carboxyl group, and a variable side chain are bonded.

Proteinogenic amino acids are amino acids that are incorporated biosynthetically into proteins during translation.

The end with a free amino group is known as the N-terminus or amino terminus, whereas the end of the protein with a free carboxyl group is known as the C-terminus or carboxy terminus (the sequence of the protein is written from N-terminus to C-terminus, from left to right).

The N-terminus (also known as the amino-terminus, NH 2 -terminus, N-terminal end or amine-terminus) is the start of a protein or polypeptide referring to the free amine group (-NH 2 ) located at the end of a polypeptide.

Proteins can interact with many types of molecules, including with other proteins, with lipids, with carboyhydrates, and with DNA.

Protein–protein interactions (PPIs) are the physical contacts of high specificity established between two or more protein molecules as a result of biochemical events steered by electrostatic forces including the hydrophobic effect.

Proteins can interact with many types of molecules, including with other proteins, with lipids, with carboyhydrates, and with DNA.

DNA-binding proteins are proteins that have DNA-binding domains and thus have a specific or general affinity for single- or double-stranded DNA.

Proteins are large biomolecules, or macromolecules, consisting of one or more long chains of amino acid residues. Most proteins consist of linear polymers built from series of up to 20 different L -α- amino acids.

In the form of proteins, amino acid residues form the second-largest component (water is the largest) of human muscles and other tissues.