Peptides in Biological Definition

Major histocompatibility complex

... interaction is that T cells should ignore self peptides while reacting appropriately to the foreign peptides. Foreign peptides that provoke an immune response are termed ... domains, α 1 , α 2 , which present peptides derived from cytosolic proteins to the immune ...

Neurotransmitter

... into small-molecule transmitters and neuroactive peptides . Around 10 small-molecule neurotransmitters are ... in autonomic neurons. Over 50 neuroactive peptides have been found, among them hormones such as LH ... by second messenger systems. Neuroactive peptides are synthesized in the neuron's soma and are ...

Peptide

... peptides (from the Greek ... a lone pair of electrons available for bonding. peptides (like proteins) occur in nature and are ... of which are not yet understood. Antimicrobial peptides generally disrupt the membranes of a target ...

Peptide

... peptides (from the Greek ... a lone pair of electrons available for bonding. peptides (like proteins) occur in nature and are ... of which are not yet understood. Antimicrobial peptides generally disrupt the membranes of a target ...

Amino acid

... biochemical building blocks. They form short polymer chains called peptides or polypeptides which in turn form structures called proteins . ... together with unsaturated amino acids in lantibiotics (antibiotic peptides of microbial origin). 1-Aminocyclopropane-1-carboxylic acid ( ACC ) is a ...

Proteome

... proteomics. Mass mapping identifies a protein by cleaving it into short peptides and then deduces the protein's identity by matching the observed peptide ... on the other hand, can get sequence information from individual peptides by isolating them, colliding them with a nonreactive gas, and then ...

Alpha helix

... was first postulated by Linus Pauling , Robert Corey , and Herman Branson in 1951 based on the known crystal structures of amino acids and peptides and Pauling's prediction of planar peptide bonds . The amino acids in an α helix are arranged in a helical structure, about 5 wide. ...

Biopolymer

... A biopolymer is a polymer found in nature. Starch , proteins and peptides , and DNA and RNA are all examples of biopolymers, in which the monomer units, respectively, are sugars , amino acids , and nucleic acids . ...

Helper T cell

... cell proliferates and differentiates into activated T H cells and memory T H cells. Activated T H cells secrete cytokines , proteins or peptides that stimulate other lymphocytes ; the most common is interleukin-2 (IL-2), which is a potent T cell growth factor. Activated, proliferating T ...

Hormone

... and thyroxine . Peptide hormones consist of chains of amino acids. Examples of small peptide hormones are TRH and vasopressin . peptides composed of scores or hundreds of amino acids are referred to as proteins. Examples of protein hormones include insulin and growth hormone. ...

Immune system

... that kill virally-infected cells, contain surface-mounted receptors that they use to determine if a given cell is virally infected by reading the peptides displayed on its MHC molecules. During their development, T cells are tested for self-reactivity. If a given cell contains receptors that bind ...

Immunology

... of complexity of the immune system can be seen from simple phagocytotic protection of single celled organisms, to circulating antimicrobial peptides in insects to lymphoid organs in vertebrates. Of course, like much of evolutionary, this is often seen from the anthropocentric aspect, but it must ...

Mitochondrion

... to manufacture their own RNAs and proteins . ( See: protein synthesis ). This nonchromosomal DNA encodes a small number of mitochondrial peptides (13 in humans) that are integrated into the inner mitochondrial membrane, along with polypeptides encoded by genes that reside in the host cell's ...

Mitochondrion

... to manufacture their own RNAs and proteins . ( See: protein synthesis ). This nonchromosomal DNA encodes a small number of mitochondrial peptides (13 in humans) that are integrated into the inner mitochondrial membrane, along with polypeptides encoded by genes that reside in the host cell's ...

Origin of life

... Systems. Academic Press, London and New York, p. 359. External links Astrobiology and the origins of life "SELF-REPLICATION: Even peptides do it" by Stuart A. Kauffman Cairns Smith illustration of a possible solution using crystalline behaviors of clays Model of origin of ...

Protein

... long chains of amino acids are almost universally referred to as proteins, but shorter strings of amino acids are referred to as "polypeptides," " peptides " or very rarely "oligopeptides". The dividing line is somewhat undefined, although a polypeptide may be less likely to have tertiary structure and ...

Proteolysis

... for several purposes. They include Removal of N-terminal methionine residues after translation . Removal of the signal sequence of peptides after their transport through a membrane Separation of viral proteins that were translated from a monocistronic mRNA Digestion of ...

Proteomics

... and its isoelectric point . X-ray crystallography and nuclear magnetic resonance are used to characterize the three-dimensional structure of peptides and proteins . Tandem mass spectrometry combined with reverse phase chromatography or 2-D electrophoresis is used to identify and quantify ...

Secondary metabolite

... alkaloids , terpenoids , polyketides , aliphatic , aromatic , and heteroaromatic organic acids , phenols , iridoids , steroids , saponins , peptides , ethereal oils , resins and balsams . List of most important secondary metabolites of plants : Class Alkaloids : Hyoscyamine , ...