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The small intestine or small bowel is an organ in the gastrointestinal tract where most of the absorption of nutrients from food takes place. It lies between the stomach and large intestine, and receives bile and pancreatic juice through the pancreatic duct to aid in digestion. The small intestine is about 5.5 metres long and folds many times to fit in the abdomen. Although it is longer than the large intestine, it is called the small intestine because it is narrower in diameter.
Secretin is a hormone that regulates water homeostasis throughout the body and influences the environment of the duodenum by regulating secretions in the stomach, pancreas, and liver. It is a peptide hormone produced in the S cells of the duodenum, which are located in the intestinal glands. In humans, the secretin peptide is encoded by the SCT gene.
Substance P (SP) is an undecapeptide and a type of neuropeptide, belonging to the tachykinin family of neuropeptides. It acts as a neurotransmitter and a neuromodulator. Substance P and the closely related neurokinin A (NKA) are produced from a polyprotein precursor after alternative splicing of the preprotachykinin A gene. The deduced amino acid sequence of substance P is as follows:
Proteinogenic amino acids are amino acids that are incorporated biosynthetically into proteins during translation. The word "proteinogenic" means "protein creating". Throughout known life, there are 22 genetically encoded (proteinogenic) amino acids, 20 in the standard genetic code and an additional 2 that can be incorporated by special translation mechanisms.
Cholecystokinin is a peptide hormone of the gastrointestinal system responsible for stimulating the digestion of fat and protein. Cholecystokinin, formerly called pancreozymin, is synthesized and secreted by enteroendocrine cells in the duodenum, the first segment of the small intestine. Its presence causes the release of digestive enzymes and bile from the pancreas and gallbladder, respectively, and also acts as a hunger suppressant.
Digestive enzymes take part in the chemical process of digestion, which follows the mechanical process of digestion. Food consists of macromolecules of proteins, carbohydrates, and fats that need to be broken down chemically by digestive enzymes in the mouth, stomach, pancreas, and duodenum, before being able to be absorbed into the bloodstream. Initial breakdown is achieved by chewing (mastication) and the use of digestive enzymes of saliva. Once in the stomach further mechanical churning takes place mixing the food with secreted gastric acid. Digestive gastric enzymes take part in some of the chemical process needed for absorption. Most of the enzymatic activity, and hence absorption takes place in the duodenum.
Amylin, or islet amyloid polypeptide (IAPP), is a 37-residue peptide hormone. It is co-secreted with insulin from the pancreatic β-cells in the ratio of approximately 100:1 (insulin:amylin). Amylin plays a role in glycemic regulation by slowing gastric emptying and promoting satiety, thereby preventing post-prandial spikes in blood glucose levels.
Growth hormone–releasing hormone (GHRH), also known as somatocrinin or by several other names in its endogenous forms and as somatorelin (INN) in its pharmaceutical form, is a releasing hormone of growth hormone (GH). It is a 44-amino acid peptide hormone produced in the arcuate nucleus of the hypothalamus.
Kassinin is a peptide derived from the Kassina frog. It belongs to tachykinin family of neuropeptides. It is secreted as a defense response, and is involved in neuropeptide signalling.
A tetrapeptide is a peptide, classified as an oligopeptide, since it only consists of four amino acids joined by peptide bonds. Many tetrapeptides are pharmacologically active, often showing affinity and specificity for a variety of receptors in protein-protein signaling. Present in nature are both linear and cyclic tetrapeptides (CTPs), the latter of which mimics protein reverse turns which are often present on the surface of proteins and druggable targets. Tetrapeptides may be cyclized by a fourth peptide bond or other covalent bonds.
Corticotropin-like intermediate [lobe] peptide (CLIP), also known as adrenocorticotropic hormone fragment 18-39, is a naturally occurring, endogenous neuropeptide with a docosapeptide structure and the amino acid sequence Arg-Pro-Val-Lys-Val-Tyr-Pro-Asn-Gly-Ala-Glu-Asp-Glu-Ser-Ala-Glu-Ala-Phe-Pro-Leu-Glu-Phe. CLIP is generated as a proteolyic cleavage product of adrenocorticotropic hormone (ACTH), which in turn is a cleavage product of proopiomelanocortin (POMC). Its physiological role has been investigated in various tissues, specifically in the central nervous system.
Neurokinin 1 (NK1) antagonists (-pitants) are a novel class of medications that possesses unique antidepressant, anxiolytic, and antiemetic properties. NK-1 antagonists boost the efficacy of 5-HT3 antagonists to prevent nausea and vomiting. The discovery of neurokinin 1 (NK1) receptor antagonists was a turning point in the prevention of nausea and vomiting associated with cancer chemotherapy.
The tachykinin receptor 1 (TACR1) also known as neurokinin 1 receptor (NK1R) or substance P receptor (SPR) is a G protein coupled receptor found in the central nervous system and peripheral nervous system. The endogenous ligand for this receptor is Substance P, although it has some affinity for other tachykinins. The protein is the product of the TACR1 gene.
Big dynorphin is an endogenous opioid peptide of the dynorphin family that is composed of both dynorphin A and dynorphin B. Big dynorphin has the amino acid sequence: Tyr-Gly-Gly-Phe-Leu-Arg-Arg-Ile-Arg-Pro-Lys-Leu-Lys-Trp-Asp-Asn-Gln-Lys-Arg-Tyr-Gly-Gly-Phe-Leu-Arg-Arg-Gln-Phe-Lys-Val-Val-Thr. It has nociceptive and anxiolytic-like properties, as well as effects on memory in mice.
The discovery of an orally inactive peptide from snake venom established the important role of angiotensin converting enzyme (ACE) inhibitors in regulating blood pressure. This led to the development of captopril, the first ACE inhibitor. When the adverse effects of captopril became apparent new derivates were designed. Then after the discovery of two active sites of ACE: N-domain and C-domain, the development of domain-specific ACE inhibitors began.
Orexin-A, also known as hypocretin-1, is a naturally occurring neuropeptide and orexin isoform. The orexinergic nucleus in the lateral hypothalamus is the primary orexin projection system in the brain.
Lixisenatide is a once-daily injectable GLP-1 receptor agonist for the treatment of type 2 diabetes.
Leumorphin, also known as dynorphin B1–29, is a naturally occurring endogenous opioid peptide. Derived as a proteolytic cleavage product of residues 226-254 of prodynorphin, leumorphin is a nonacosapeptide and has the sequence Tyr-Gly-Gly-Phe-Leu-Arg-Arg-Gln-Phe-Lys-Val-Val-Thr-Arg-Ser-Gln-Glu-Asp-Pro-Asn-Ala-Tyr-Ser-Gly-Glu-Leu-Phe-Asp-Ala. It can be further reduced to dynorphin B and dynorphin B-14 by pitrilysin metallopeptidase 1, an enzyme of the endopeptidase family. Leumorphin behaves as a potent and selective κ-opioid receptor agonist, similarly to other endogenous opioid peptide derivatives of prodynorphin.
Modified GRF (1-29) often abbreviated as mod GRF (1-29), originally known as tetrasubstituted GRF (1-29), is a term used to identify a 29 amino acid peptide analogue of growth-hormone-releasing hormone (GHRH), a releasing hormone of growth hormone (GH). It is a modified version of the shortest fully functional fragment of GHRH, often referred to as growth hormone releasing factor (1-29), and also known by its standardized name, sermorelin.
Bulevirtide, sold under the brand name Hepcludex, is an antiviral medication for the treatment of chronic hepatitis D.
References
- ↑ Jelovac, Nikola; Sikiric, Predrag; Rucman, Rudolf; Petek, Marijan; Marovic, Anton; Perovic, Darko; Seiwerth, Sven; Mise, Stjepan; Turkovic, Branko; Dodig, Goran; Miklic, Pavle; Buljat, Gojko; Prkacin, Ingrid (1999). "Pentadecapeptide BPC 157 attenuates disturbances induced by neuroleptics: the effect on catalepsy and gastric ulcers in mice and rats". European Journal of Pharmacology. 379 (1): 19–31. doi:10.1016/S0014-2999(99)00486-0. PMID 10499368.
- ↑ "PUBCHEM". pubchem.ncbi.nlm.nih.gov. Retrieved 1 March 2021.
- ↑ "2022 Prohibited List: SUBSTANCES AND METHODS PROHIBITED AT ALL TIMES (IN- AND OUT-OF-COMPETITION)" (PDF). World Anti-Doping Agency. WADA. Retrieved 21 February 2022.
- ↑ Sikiric, P.; Seiwerth, S.; Brcic, L.; Blagaic, A. B.; Zoricic, I.; Sever, M.; Klicek, R.; Radic, B.; Keller, N.; Sipos, K.; Jakir, A.; Udovicic, M.; Tonkic, A.; Kokic, N.; Turkovic, B.; Mise, S.; Anic, T. (2006). "Stable gastric pentadecapeptide BPC 157 in trials for inflammatory bowel disease (PL-10, PLD-116, PL 14736, Pliva, Croatia). Full and distended stomach, and vascular response". Inflammopharmacology. 14 (5–6): 214–21. doi:10.1007/s10787-006-1531-7. PMID 17186181. S2CID 24132425.
- ↑ Cerovecki, Tomislav; Bojanic, Ivan; Brcic, Luka; Radic, Bozo; Vukoja, Ivan; Seiwerth, Sven; Sikiric, Predrag (September 2010). "Pentadecapeptide BPC 157 (PL 14736) improves ligament healing in the rat". Journal of Orthopaedic Research. 28 (9): 1155–1161. doi:10.1002/jor.21107. ISSN 1554-527X. PMID 20225319. S2CID 22085833.
- ↑ Sikiric, P; Seiwerth, S; Rucman, R; Kolenc, D; Vuletic, LB; Drmic, D; Grgic, T; Strbe, S; Zukanovic, G; Crvenkovic, D; Madzarac, G; Rukavina, I; Sucic, M; Baric, M; Starcevic, N; Krstonijevic, Z; Bencic, ML; Filipcic, I; Rokotov, DS; Vlainic, J (2016). "Brain-gut Axis and Pentadecapeptide BPC 157: Theoretical and Practical Implications". Current Neuropharmacology. 14 (8): 857–865. doi:10.2174/1570159x13666160502153022. PMC 5333585 . PMID 27138887.