heptapeptide

ヘプタペプチド

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2012/12/26 20:34:24」(JST)

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"Peptides" redirects here. For the journal, see Peptides (journal).

A tetrapeptide (example Val-Gly-Ser-Ala) with
green marked amino end (L-Valine) and

blue marked carboxyl end (L-Alanine).

Trans peptide bond marked blue

Cis peptide bond marked blue

Peptides (from the Greek πεπτός, "digested" from πέσσειν "to digest") are short polymers of amino acid monomers linked by peptide bonds, the covalent chemical bonds formed between two molecules when the carboxyl group of one molecule reacts with the amino group of the other molecule. Peptides are distinguished from proteins on the basis of size, typically containing fewer than 50 monomer units. The shortest peptides are dipeptides, consisting of two amino acids joined by a single peptide bond. There are also tripeptides, tetrapeptides, etc.

Amino acids which have been incorporated into a peptide are termed "residues"; every peptide has a N-terminus and C-terminus residue on the ends of the peptide (except for cyclic peptides). A polypeptide is a long, continuous, and unbranched peptide. Proteins consist of one or more polypeptides arranged in a biologically functional way and are often bound to cofactors, or other proteins.

The size boundaries that distinguish peptides, polypeptides, and proteins are arbitrary. Long peptides such as amyloid beta can be considered proteins, where as small proteins such as insulin can be considered peptides.

Peptide classes

Peptides are divided into several classes, depending on how they are produced:

Milk peptides 

Milk peptides are formed from milk proteins by enzymatic breakdown by digestive enzymes or by the proteinases formed by lactobacilli during the fermentation of milk.

Ribosomal peptides 

Ribosomal peptides are synthesized by translation of mRNA. They are often subjected to proteolysis to generate the mature form. These function, typically in higher organisms, as hormones and signaling molecules. Some organisms produce peptides as antibiotics, such as microcins. Since they are translated, the amino acid residues involved are restricted to those utilized by the ribosome. However, these peptides frequently have posttranslational modifications, such as phosphorylation, hydroxylation, sulfonation, palmitylation, glycosylation and disulfide formation. In general, they are linear, although lariat structures have been observed. More exotic manipulations do occur, such as racemization of L-amino acids to D-amino acids in platypus venom.

Nonribosomal peptides 

These peptides are assembled by enzymes that are specific to each peptide, rather than by the ribosome. The most common non-ribosomal peptide is glutathione, which is a component of the antioxidant defenses of most aerobic organisms. Other nonribosomal peptides are most common in unicellular organisms, plants, and fungi and are synthesized by modular enzyme complexes called nonribosomal peptide synthetases. These complexes are often laid out in a similar fashion, and they can contain many different modules to perform a diverse set of chemical manipulations on the developing product. These peptides are often cyclic and can have highly-complex cyclic structures, although linear nonribosomal peptides are also common. Since the system is closely related to the machinery for building fatty acids and polyketides, hybrid compounds are often found. The presence of oxazoles or thiazoles often indicates that the compound was synthesized in this fashion.

Peptones

See also Tryptone

Peptones are derived from animal milk or meat digested by proteolytic digestion. In addition to containing small peptides, the resulting spray-dried material includes fats, metals, salts, vitamins and many other biological compounds. Peptone is used in nutrient media for growing bacteria and fungi.

Peptide fragments 

Peptide fragments refer to fragments of proteins that are used to identify or quantify the source protein. Often these are the products of enzymatic degradation performed in the laboratory on a controlled sample, but can also be forensic or paleontological samples that have been degraded by natural effects.

Peptide synthesis

Main article: Peptide synthesis

Solid-phase peptide synthesis on a rink amide resin using Fmoc-α-amine-protected amino acid

Peptides in molecular biology

Peptides have recently received prominence in molecular biology for several reasons. The first is that peptides allow the creation of peptide antibodies in animals without the need to purify the protein of interest. This involves synthesizing antigenic peptides of sections of the protein of interest. These will then be used to make antibodies in a rabbit or mouse against the protein.

Another reason is that peptides have become instrumental in mass spectrometry, allowing the identification of proteins of interest based on peptide masses and sequence. In this case the peptides are most often generated by in-gel digestion after electrophoretic separation of the proteins.

Peptides have recently been used in the study of protein structure and function. For example, synthetic peptides can be used as probes to see where protein-peptide interactions occur- see the page on Protein tags.

Inhibitory peptides are also used in clinical research to examine the effects of peptides on the inhibition of cancer proteins and other diseases.

Well-known peptide families in humans

The peptide families in this section are ribosomal peptides, usually with hormonal activity. All of these peptides are synthesized by cells as longer "propeptides" or "proproteins" and truncated prior to exiting the cell. They are released into the bloodstream where they perform their signalling functions.

Tachykinin peptides

• Substance P
• Kassinin
• Neurokinin A
• Eledoisin
• Neurokinin B

Vasoactive intestinal peptides

• VIP (Vasoactive Intestinal Peptide; PHM27)
• PACAP Pituitary Adenylate Cyclase Activating Peptide
• Peptide PHI 27 (Peptide Histidine Isoleucine 27)
• GHRH 1-24 (Growth Hormone Releasing Hormone 1-24)
• Glucagon
• Secretin

Pancreatic polypeptide-related peptides

• NPY (NeuroPeptide Y)
• PYY (Peptide YY)
• APP (Avian Pancreatic Polypeptide)
• PPY Pancreatic PolYpeptide

Opioid peptides

• Proopiomelanocortin (POMC) peptides
• Enkephalin pentapeptides
• Prodynorphin peptides

Calcitonin peptides

• Calcitonin
• Amylin
• AGG01

Other peptides

• B-type Natriuretic Peptide (BNP) - produced in myocardium & useful in medical diagnosis
• Lactotripeptides - Lactotripeptides might reduce blood pressure, although the evidence is mixed.

Notes on terminology

Length:

• A polypeptide is a single linear chain of amino acids.
• A protein is one or more polypeptides more than about 50 amino acids long.
• An oligopeptide (or simply a peptide) is a polypeptide less than 30-50 amino acids long.

Number of amino acids:

• A monopeptide has one amino acid.
• A dipeptide has two amino acids.
• A tripeptide has three amino acids.
• A tetrapeptide has four amino acids.
• A pentapeptide has five amino acids.
• A hexapeptide has six amino acids.
• A heptapentide has seven amino acids.
• An octapeptide has eight amino acids (e.g., angiotensin II).
• A nonapeptide has nine amino acids (e.g., oxytocin).
• A decapeptide has ten amino acids (e.g., gonadotropin-releasing hormone & angiotensin I).
• An undecapeptide (or monodecapeptide) has eleven amino acids, a dodecapeptide (or didecapeptide) has twelve amino acids, a tridecapeptide has thirteen amino acids, and so forth.
• An icosapeptide has twenty amino acids, a tricontapeptide has thirty amino acids, a tetracontapeptide has forty amino acids, and so forth.

See also: IUPAC numerical multiplier

Function:

• A neuropeptide is a peptide that is active in association with neural tissue.
• A lipopeptide is a peptide that has a lipid connected to it, and pepducins are lipopeptides that interact with GPCRs.
• A peptide hormone is a peptide that acts as a hormone.
• A proteose is a mixture of peptides produced by the hydrolysis of proteins. The term is somewhat archaic.

See also

• Antineoplaston
• Argireline
• Beefy meaty peptide
• Bis-peptide
• Epidermal Growth Factor
• Journal of Peptide Science
• Lactotripeptides
• Pancreatic hormone
• Peptide Spectral Library
• Peptide synthesis
• Peptidomimetics (such as peptoids and β-peptides) to peptides, but with different properties.
• Protein tag, describing addition of peptide sequences to enable protein isolation
• Ribosome
• Translation

References

UpToDate Contents

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• 1. 冠動脈疾患における血小板糖蛋白（GP）IIb/IIIa受容体拮抗薬に関する初期臨床試験 early trials of platelet glycoprotein iib iiia receptor inhibitors in coronary heart disease

English Journal

• An interleukin 13 receptor α 2-specific peptide homes to human Glioblastoma multiforme xenografts.

• Pandya H, Gibo DM, Garg S, Kridel S, Debinski W.SourceCorresponding author: Waldemar Debinski, MD, PhD, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157. debinski@wfubmc.edu.
• Neuro-oncology.Neuro Oncol.2012 Jan;14(1):6-18. Epub 2011 Sep 26.
• Interleukin 13 receptor α 2 (IL-13Rα2) is a glioblastoma multiforme (GBM)-associated plasma membrane receptor, a brain tumor of dismal prognosis. Here, we isolated peptide ligands for IL-13Rα2 with use of a cyclic disulphide-constrained heptapeptide phages display library and 2 in vitro biopannin
• PMID 21946118

• Theoretical study of the Raman optical activity spectra of 3(10) -helical polypeptides.

• Jacob CR.SourceKarlsruhe Institute of Technology (KIT), Center for Functional Nanostructures (CFN), Wolfgang-Gaede-Str. 1a, 76131 Karlsruhe (Germany). christoph.jacob@kit.edu.
• Chemphyschem : a European journal of chemical physics and physical chemistry.Chemphyschem.2011 Dec 9;12(17):3291-306. doi: 10.1002/cphc.201100593. Epub 2011 Nov 3.
• Raman optical activity (ROA) spectroscopy is a promising analytical method for studying the structure and conformation of polypeptides and proteins in solution. However, the structural information obtained from such vibrational spectra is only indirect and theoretical studies are often necessary to
• PMID 22052852

Japanese Journal

• Total Synthesis of Stylissatin A, A Cyclic Peptide That Inhibits Nitric Oxide Production

• , , , ,
• Bulletin of the Chemical Society of Japan 88(4), 600-609, 2015
• … Stylissatin A is a proline-rich cyclic heptapeptide isolated from the Papua New Guinean marine sponge Stylissa massa. …
• NAID 130005064994

• Total Synthesis of Stylissatin A, A Cyclic Peptide That Inhibits Nitric Oxide Production

• , , , ,
• Bulletin of the Chemical Society of Japan advpub(0), 2015
• … Stylissatin A is a proline-rich cyclic heptapeptide isolated from the Papua New Guinean marine sponge Stylissa massa. …
• NAID 130004719766

• Preparation and characterization of surfactin-modified silica stationary phase for reversed-phase and hydrophilic interaction liquid chromatography

• Ohyama Kaname,Inoue Yu,Kishikawa Naoya,Kuroda Naotaka
• Journal of Chromatography A 1371, 257-260, 2014-12-05
• … Surfactin, a cyclic heptapeptide, is an efficient biosurfactant produced by Bacillus subtilis that comprises seven amino acids and a β-hydroxyl fatty acid. …
• NAID 120005526608

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