Growth hormone–releasing hormone

growth hormone-releasing hormoneGHRHgrowth hormone releasing hormone
Sermorelin, a functional peptide fragment of GHRH, has been used in the diagnosis of deficiencies in growth hormone secretion. Tesamorelin, under the trade name Egrifta, received U.S. Food and Drug Administration approval in 2010 for the treatment of lipodystrophy in HIV patients under highly active antiretroviral therapy, and, in 2011, was investigated for effects on certain cognitive tests in the elderly. As a category, the use of GHRH analogs by professional athletes may be prohibited by restrictions on doping in sport because they act as growth hormone secretagogues.

Protein primary structure

amino acid sequenceprotein sequencesequence
The C-terminal carboxylate group of a polypeptide can also be modified, e.g., Finally, the peptide side chains can also be modified covalently, e.g., Most of the polypeptide modifications listed above occur post-translationally, i.e., after the protein has been synthesized on the ribosome, typically occurring in the endoplasmic reticulum, a subcellular organelle of the eukaryotic cell. Many other chemical reactions (e.g., cyanylation) have been applied to proteins by chemists, although they are not found in biological systems. In addition to those listed above, the most important modification of primary structure is peptide cleavage (by chemical hydrolysis or by proteases).

Growth hormone

human growth hormoneHGHgrowth hormones
Growth hormone (GH) or somatotropin, also known as human growth hormone (hGH or HGH) in its human form, is a peptide hormone that stimulates growth, cell reproduction, and cell regeneration in humans and other animals. It is thus important in human development. GH also stimulates production of IGF-1 and increases the concentration of glucose and free fatty acids. It is a type of mitogen which is specific only to the receptors on certain types of cells. GH is a 191-amino acid, single-chain polypeptide that is synthesized, stored and secreted by somatotropic cells within the lateral wings of the anterior pituitary gland.

Adrenocorticotropic hormone

ACTHcorticotropinadrenocorticotrophic hormone
The removal of the signal peptide during translation produces the 241-amino acid polypeptide POMC, which undergoes a series of post-translational modifications such as phosphorylation and glycosylation before it is proteolytically cleaved by endopeptidases to yield various polypeptide fragments with varying physiological activity. These fragments include: In order to regulate the secretion of ACTH, many substances secreted within this axis exhibit slow/intermediate and fast feedback-loop activity. Glucocorticoids secreted from the adrenal cortex work to inhibit CRH secretion by the hypothalamus, which in turn decreases anterior pituitary secretion of ACTH.

Organic compound

syntheticorganicorganic compounds
Further compounds of prime importance in biochemistry are antigens, carbohydrates, enzymes, hormones, lipids and fatty acids, neurotransmitters, nucleic acids, proteins, peptides and amino acids, lectins, vitamins, and fats and oils. Compounds that are prepared by reaction of other compounds are known as "synthetic". They may be either compounds that already are found in plants or animals or those that do not occur naturally. Most polymers (a category that includes all plastics and rubbers) are organic synthetic or semi-synthetic compounds. Many organic compounds—two examples are ethanol and insulin—are manufactured industrially using organisms such as bacteria and yeast.

Follicle-stimulating hormone

FSHfollicle stimulating hormonefollicle-stimulating hormone (FSH)
Follicle-stimulating hormone (FSH) is a gonadotropin, a glycoprotein polypeptide hormone. FSH is synthesized and secreted by the gonadotropic cells of the anterior pituitary gland, and regulates the development, growth, pubertal maturation, and reproductive processes of the body. FSH and luteinizing hormone (LH) work together in the reproductive system. FSH is a 35.5 kDa glycoprotein heterodimer, consisting of two polypeptide units, alpha and beta. Its structure is similar to those of luteinizing hormone (LH), thyroid-stimulating hormone (TSH), and human chorionic gonadotropin (hCG).


GHRP-2GHRP2Growth Hormone Releasing Peptide
Pralmorelin (INN) (brand name GHRP Kaken 100; former developmental code names KP-102, GPA-748, WAY-GPA-748), also known as pralmorelin hydrochloride (JAN) and pralmorelin dihydrochloride (USAN), as well as, notably, growth hormone-releasing peptide 2 (GHRP-2), is a growth hormone secretagogue (GHS) used as a diagnostic agent that is marketed by Kaken Pharmaceutical in Japan in a single-dose formulation for the assessment of growth hormone deficiency (GHD). Pralmorelin is an orally-active, synthetic peptide drug, specifically, an analogue of met-enkephalin, with the amino acid sequence D -Ala- D -(β-naphthyl)-Ala-Ala-Trp- D -Phe-Lys-NH 2.


PRLlactationprolactin secretion
Vasoactive intestinal peptide and peptide histidine isoleucine help to regulate prolactin secretion in humans, but the functions of these hormones in birds can be quite different. Prolactin follows diurnal and ovulatory cycles. Prolactin levels peak during REM sleep and in the early morning. Many mammals experience a seasonal cycle. During pregnancy, high circulating concentrations of estrogen and progesterone increase prolactin levels by 10- to 20-fold. Estrogen and progesterone inhibit the stimulatory effects of prolactin on milk production. The abrupt drop of estrogen and progesterone levels following delivery allow prolactin—which temporarily remains high—to induce lactation.

Sex steroid

sex hormonesex hormonessex steroids
The polypeptide hormones luteinizing hormone, follicle-stimulating hormone and gonadotropin-releasing hormone are usually not regarded as sex hormones, although they play major sex-related roles. Natural sex steroids are made by the gonads (ovaries or testes), by adrenal glands, or by conversion from other sex steroids in other tissue such as liver or fat. In many contexts, the two main classes of sex steroids are androgens and estrogens, of which the most important human derivatives are testosterone and estradiol, respectively. Other contexts will include progestogens as a third class of sex steroids, distinct from androgens and estrogens.


pubescentpubescencesexual development
Neurokinin B (a tachykinin peptide) and kisspeptin (a neuropeptide), both present in KNDy neurons of the hypothalamus, are critical parts of the control system that switches on the release of GnRH at the start of puberty. GnRH (gonadotropin-releasing hormone) is a peptide hormone released from the hypothalamus which stimulates gonadotrope cells of the anterior pituitary. LH (luteinizing hormone) is a larger protein hormone secreted into the general circulation by gonadotrope cells of the anterior pituitary gland. The main target cells of LH are the Leydig cells of testes and the theca cells of the ovaries.


A tripeptide is a peptide derived from three amino acids joined by two or sometimes three peptide bonds. As for proteins, the function of peptides is determined by the consistuent amino acids and their sequence. The simplest tripeptide is glycylglycylglycine. In terms of scientific investigations, the dominant tripeptide is glutathione (γ- L -Glutamyl- L -cysteinylglycine), which serves many roles in many forms of life. Eisenin (pGlu-Gln-Ala-OH) is a peptide with immunological activity that is isolated from the Japanese marine alga, Eisenia bicyclis, which more commonly is known as, Arame.

Amino acid

amino acidsresiduesresidue
Amino acids have zero mobility in electrophoresis at their isoelectric point, although this behaviour is more usually exploited for peptides and proteins than single amino acids. Zwitterions have minimum solubility at their isoelectric point, and some amino acids (in particular, with non-polar side chains) can be isolated by precipitation from water by adjusting the pH to the required isoelectric point. Amino acids are the structural units (monomers) that make up proteins. They join together to form short polymer chains called peptides or longer chains called either polypeptides or proteins.


proteinsproteinaceousstructural proteins
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.

Amyloid beta

beta amyloidbeta-amyloidβ-amyloid
Early NMR-derived models of a 26-aminoacid polypeptide from amyloid beta (Aβ 10-35) show a collapsed coil structure devoid of significant secondary structure content. However, the most recent (2012) NMR structure of (Aβ 1-40) has significant secondary and tertiary structure. Replica exchange molecular dynamics studies suggested that amyloid beta can indeed populate multiple discrete structural states; more recent studies identified a multiplicity of discrete conformational clusters by statistical analysis.

Cyclic peptide

cyclic peptidescycliccyclic dipeptide
Cyclic peptides are polypeptide chains which contain a circular sequence of bonds. This can be through a connection between the amino and carboxyl ends of the peptide, for example in cyclosporin; a connection between the amino end and a side chain, for example in bacitracin; the carboxyl end and a side chain, for example in colistin; or two side chains or more complicated arrangements, for example in amanitin. Many cyclic peptides have been discovered in nature and many others have been synthesized in the laboratory. Their length ranges from just two amino acid residues to hundreds.

Macromolecular assembly

macromolecular assembliesBiological Unitmacromolecular structures
The term macromolecular assembly (MA) refers to massive chemical structures such as viruses and non-biologic nanoparticles, cellular organelles and membranes and ribosomes, etc. that are complex mixtures of polypeptide, polynucleotide, polysaccharide or other polymeric macromolecules. They are generally of more than one of these types, and the mixtures are defined spatially (i.e., with regard to their chemical shape), and with regard to their underlying chemical composition and structure.


proteolyticprotein degradationpolyprotein
Proteins that are to be targeted to a particular organelle or for secretion have an N-terminal signal peptide that directs the protein to its final destination. This signal peptide is removed by proteolysis after their transport through a membrane. Some proteins and most eukaryotic polypeptide hormones are synthesized as a large precursor polypeptide known as a polyprotein that requires proteolytic cleavage into individual smaller polypeptide chains. The polyprotein pro-opiomelanocortin (POMC) contains many polypeptide hormones. The cleavage pattern of POMC, however, may vary between different tissues, yielding different sets of polypeptide hormones from the same polyprotein.


N-terminalN terminusN-
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. Normally the amine group is bonded to another carboxylic group in a protein to make it a chain, but since the end of a protein has only 1 out of 2 areas chained, the free amine group is referred to the N-terminus. By convention, peptide sequences are written N-terminus to C-terminus, left to right in LTR languages.


There are three main classes of biopolymers: polysaccharides, polypeptides, and polynucleotides. In living cells, they may be synthesized by enzyme-mediated processes, such as the formation of DNA catalyzed by DNA polymerase. The synthesis of proteins involves multiple enzyme-mediated processes to transcribe genetic information from the DNA to RNA and subsequently translate that information to synthesize the specified protein from amino acids. The protein may be modified further following translation in order to provide appropriate structure and functioning. There are other biopolymers such as rubber, suberin, melanin, and lignin.


C-terminalC-terminal domainC terminus
The C-terminus (also known as the carboxyl-terminus, carboxy-terminus, C-terminal tail, C-terminal end, or COOH-terminus) is the end of an amino acid chain (protein or polypeptide), terminated by a free carboxyl group (-COOH). When the protein is translated from messenger RNA, it is created from N-terminus to C-terminus. The convention for writing peptide sequences is to put the C-terminal end on the right and write the sequence from N- to C-terminus. Each amino acid has a carboxyl group and an amine group. Amino acids link to one another to form a chain by a dehydration reaction which joins the amine group of one amino acid to the carboxyl group of the next.

Nonribosomal peptide

nonribosomal peptide synthetasenonribosomal peptide synthetasesnon-ribosomal peptide synthesis
Termination: The TE-domain (thio-esterase domain) hydrolyzes the completed polypeptide chain from the PCP-domain of the previous module, thereby often forming cyclic amides (lactams) or cyclic esters (lactones). Also, the peptide can be released by an R-domain that reduces the thioester bond to terminal aldehyde or alcohol. Epothilone. Esterase. Ribosomally synthesized and post-translationally modified peptides.

Growth hormone secretagogue

growth hormone-releasing peptides
They include agonists of the ghrelin/growth hormone secretagogue receptor (GHSR), such as ghrelin (lenomorelin), pralmorelin (GHRP-2), GHRP-6, examorelin (hexarelin), ipamorelin, and ibutamoren (MK-677), and agonists of the growth hormone-releasing hormone receptor (GHRHR), such as growth hormone-releasing hormone (GHRH) (somatorelin), CJC-1295, sermorelin, and tesamorelin. Many also induce the secretion of insulin-like growth factor 1 (IGF-1), as well as of other hypothalamic-pituitary hormones such as prolactin and cortisol. The main clinical application of these agents is the treatment of growth hormone deficiency.


Peptide: Peptide hormones are made of a chain of amino acids that can range from just 3 to hundreds of amino acids. Examples include oxytocin and insulin. Their sequences are encoded in DNA and can be modified by alternative splicing and/or post-translational modification. They are packed in vesicles and are hydrophilic, meaning that they are soluble in water. Due to their hydrophilicity, they can only bind to receptors on the membrane, as travelling through the membrane is unlikely. However, some hormones can bind to intracellular receptors through an intracrine mechanism. Amino acid: Amino acid hormones are derived from amino acid, most commonly tyrosine.

Substance P

SPsubstance P (SP)
Substance P (SP) is an undecapeptide (a peptide composed of a chain of 11 amino acid residues) member of the tachykinin neuropeptide family. It is a neuropeptide, acting as a neurotransmitter and as a neuromodulator. Substance P and its closely related neurokinin A (NKA) are produced from a polyprotein precursor after differential splicing of the preprotachykinin A gene. The deduced amino acid sequence of substance P is as follows: * Arg Pro Lys Pro Gln Gln Phe Phe Gly Leu Met (RPKPQQFFGLM) with an amidation at the C-terminus. Substance P is released from the terminals of specific sensory nerves.