Peptide Hormone Action
Übersetzung für "a peptide hormone, a steroid hormone" im DeutschUmweltkrankheiten entstehen oft durch hormonelle Dysregulation durch chemische Stoffe in der Umwelt, die eine hormonelle Wirkung haben. Was aber sind Hormone? Proteine sind die Arbeitspferde der Zelle, Rezeptoren sind auch Proteine. Was genau sind Proteine? Auch Peptlde sind Proteine, aber mit einer speziellen Funktion. Steroid hormone peptide hormone genau und was hat die Kenntnis von Enzym-Funktionen mit Umweltkrankheiten zu tun?
This review describes the properties and activities of lipopeptides and peptide hormones and how the lipidation of peptide hormones could potentially produce therapeutic agents combating some of the most prevalent diseases and conditions.
Peptide hormones specific to the uptake of food and produced in the gastrointestinal tract are discussed in detail. The advantages of lipidated peptide hormones over natural peptide hormones are summarised, in terms of stability and renal clearance, with potential application as therapeutic agents. However, in the latter class of system, hydrophobic interactions are important. Amphiphilic molecules such as lipids, peptides and proteins serve as building blocks for the construction of functional assemblies in vivo , e.
Lipids are one of the simplest amphiphilic structures and are composed of a hydrophilic polar head group and a hydrophobic tail. Peptides and proteins, however, are distinct in the way in which amphiphilicity is displayed because when folded, they can display regions that are either hydrophobic or hydrophilic. Micelles form spontaneously when the concentration is above a critical micelle concentration [CMC] and temperature 5. Amphiphiles with an intermediate level of hydrophobicity can assemble into bilayer vesicles.
Vesicles are spherical, hollow, lamellar structures with an aqueous core. The hydrophobic moieties form the inner section of the bilayer, and the hydrophilic parts are exposed to the aqueous environment 6. Among all organic building blocks, peptides are very promising platforms because of their ease of synthesis, chemical diversity and their similar biological properties to proteins.
As a result of this, peptides provide a unique platform for the design of nanomaterials with controllable structural features. Peptide amphiphiles PAs may comprise sequences of hydrophobic and hydrophilic peptides or hydrophilic peptides attached to lipid chains.
The class of PA termed lipopeptide consists of one or more lipid chains attached to hydrophilic peptide sequences containing charged residues 2 , 7. A hydrophobic domain that is typically an alkyl chain attached to a peptide sequence, which favours intermolecular hydrogen bonding. Then there is a charged amino acid domain that enhances solubility in water. There is normally a distinct relationship between the amphiphilic character of a peptide and its function Peptide amphiphiles have great potential in biomedical applications 1 , 11 , 13 , 14 , 15 , 16 , 17 , 18 and can be utilised to act as therapeutic agents to treat diseases by delivering drugs.
They can then be metabolised into lipids and amino acids, which are then easily cleared by the kidneys Lipopeptides are able to form supramolecular nanostructures such as fibrils, micelles and vesicles. Lipopeptide biosurfactants surfactants of biological origin are produced by a wide variety of bacteria, fungi and yeast 7 , They are surface active compounds that have the ability to decrease the surface and interfacial tension, allowing them to disrupt biological activity as part of the organism's host defence mechanism Lipopeptides have a wide range of applications such as use as antimicrobial agents and in immune disease therapies, cosmeceuticals and also fungicides, all of which are explained in more detail in the succeeding sections.
There are many types of lipopeptides; among the most popular are the classes of surfactins, iturins and fengycins, which are produced by the Bacillus subtilis family 21 , 22 , The fact that surfactins are biosurfactants means that they have diverse functional properties such as low toxicity, biodegradability and a higher tolerance towards variation of temperature and pH TLRs are transmembrane proteins that are very important in the immune system and as a result are therapeutic targets to treat disease.
PAMPs can contain a variety of different components including lipopolysaccharide, peptidoglycan, lipopeptide and bacterial DNA. DAMPs can be intracellular proteins or proteins from the extracellular matrix 27 , Currently, 10 TLRs have been found in humans, each with a different role and target Peptide amphiphiles are employed in skincare products with the claimed ability to help stimulate collagen production.
Labelled with the dye rhodamine B, 0. The mechanism for this stimulation of collagen expression is not fully understood, but it has been reported that the KTTKS polypeptide increases the skin's extracellular matrix ECM production 37 , ECM is the outer region of a cell that supports the cells and those around it.
Various groups have looked into the use of PAs and lipopeptides as scaffolds for the production of tissue or for other applications in regenerative medicine. In one study, the linear RGD amino acid sequence was conjugated with dialkyl chains. These PAs were shown to be effective at treating spinal cord injuries in mice.
This was due to the nanofibrils inhibiting scar formation, which helped lessen the injury This is a fascinating and broad topic that has been reviewed in much detail elsewhere by the Stupp group and is therefore outside the scope of the present review 42 , 43 , 44 , 45 , 46 , A common feature for antimicrobial activity is the presence of cationic residues such as lysine or more especially arginine as these can interact with cell walls. Lipidation of peptides has been shown to improve the uptake of the peptide into the cell Uptake into the cell wall and then subsequent disruption of the cell membrane was found out to be the mode of action, which caused bacterial leakage and cell death This peptide was shown to work by the same process of incorporation into the cell membrane followed by its disruption.
The paper also showed that the PA can also be transported across the blood—brain barrier Daptomycin chemical structure, redrawn from It comprises a cyclic peptide group joined by an amide linkage to a lipid chain.
The mechanism by which daptomycin acts on bacteria has been carefully examined It works by insertion of the lipid chain into the cell wall. Daptomycin molecules then aggregate, deforming the curvature of the membrane, causing holes to form and leading to the leakage of ions from the cell.
This then causes a serious depolarization resulting in the inhibition of various synthesis processes including those of DNA, protein and RNA. This combines to cause cell death. This aggregation process may be correlated to its excellent antimicrobial activity. Lipopeptides are interesting vehicles for drug delivery with several modes of activity. It is important to distinguish between PAs with inherent therapeutic potential and those that are merely vehicles or devices. In the former case, many types of bioactive peptides have been lipidated to create active pharmaceutical ingredients APIs e.
An example of this is a TAT 48—60 fragment conjugated with one, two or four attached octanoic acid groups It was shown that the PA with four octanoic acid groups could encapsulate and retain the hydrophobic drug paclitaxel. This was deemed to be due to the high hydrophobicity of the octanoic acid groups. This encapsulation was highly efficient 6. The peptide head groups bind selectively to the receptor, while the lipid group allows the PA to cross cell membranes and also increases bioactivity through reducing metabolic degradation 56 , These fibres have high circulation times and also more importantly can cross the BBB.
This allows the normally hydrophobic cancer drug to potentially be used to treat cancers in the brain, overcoming its low circulation and high hydrophobicity The various structures formed by PAs and lipopeptides have been exploited to template distinct inorganic materials salts, metal oxides and metals , sometimes allowing for unique structures to be formed.
PA nanostructures have the potential, for example, to be used to template the bone mineral hydroxyapatite, which is the body's primary storage depot for calcium and phosphorus in bones 59 , A further avenue of interest is the incorporation of other metals, such as titanium, with mineralizing PAs to form hybrid bone implants.
In one example, a titanium alloy foam was mixed with different PAs solutions and then further allowed to mineralise calcium phosphate. This field of research is highly active and may, in the future, allow for treatment of bone diseases such as hydroxyapatite deposition disease or dystrophic calcification, among others.
Peptide hormones are hormones made up of amino acid chains that primarily have an effect on the endocrine system. The presence of amino acids in peptide hormones allows them to act on the surface of target cells via secondary messengers. This differs from steroid hormones that are lipid soluble, and so can move through the plasma membranes of target cells and act within the nuclei The endocrine system is composed of many different glands, and it can be divided into two categories: In the endocrine system, hormones are secreted into the circulatory system where they are distributed throughout the body, regulating bodily functions.
The classical endocrine glands include the pituitary gland, pancreas, thyroid gland, adrenal cortex and medulla. The primary function of these glands is to manufacture specific hormones. Many of the classical hormones are controlled by the hypothalamus and pituitary, which can also be classified as being an extension of the nervous system Gut—brain interactions are increasingly recognised as playing an important role in determining overall food intake Many peptides are synthesised and released from the gastrointestinal tract, and it has been shown that they physiologically influence eating behaviour via gut—brain signalling Interactions of gut and endocrine hormones with the brain and how they affect food intake Leptin is a hormone made by adipose cells that affects many biological mechanisms including reproduction, the immune and inflammatory response, haematopoiesis, angiogenesis, bone formation and wound healing.
More interestingly, however, leptin helps to regulate energy balance by inhibiting hunger. This occurs via a feedback mechanism in which signals are sent to key regulatory centres in the brain to inhibit food intake After leptin is released by the adipose tissue into the bloodstream, it crosses the BBB and binds to the hypothalamic leptin receptors.
This affects the activity of many hypothalamic neurones and the expression of various orexigenic appetite stimulating and anorexigenic neuropeptides.
It has been suggested that the interaction with both types of these neuropeptides underpins the mechanism of action of leptin in the hypothalamus to inhibit hunger Peripheral administration of ghrelin has been shown to stimulate food intake and decrease fat utilisation. This means it is involved in energy homeostasis, and it is the serine residue that appears to give ghrelin these effects What makes ghrelin unique is its function to increase food intake rather than decrease it, and as a result, it is a very important component of weight control.
Evidence of this was shown when a study was carried out on mice that were lacking in ghrelin. Cholecystokinin is an endogenous gut hormone mainly found in the duodenum and jejunum, which exists in several molecular forms with differing numbers of amino acids. CCK is known to act as a postprandial satiety signal, and it acts via two receptors: The CCK 1 receptor is more important in appetite control The receptors are located on the peripheral vagal afferent terminals, which transmit signals to the part of the brain stem that is associated with appetite, such as the nucleus of the solitary tract Intravenous administration of OXM in humans inhibits gastric emptying and gastric acid secretion, which leads to a feeling of satiety This feeling of satiety can cause a reduction in both food intake and overall body weight, and this is brought about by the suppression of ghrelin.
Proglucagon is the gene that is expressed in the L cells and is regulated in the gut and brain However, it differs in that it is produced in the endocrine F cells, which are located in the periphery of the pancreatic islets 77 , PP is responsible for a number of regulatory actions, such as the inhibition of pancreatic exocrine secretion, and the modulation of gastric acid secretion, and gastric emptying 79 , The amount of PP released is affected by the digestive state, i.
As a result of this, it is thought that PP could potentially play a significant role in the regulation of feeding behaviour to control energy homeostasis
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Peptidhormon - DocCheck Flexikon
Unter einem Peptidhormon versteht man einen Botenstoff (Hormon), der chemisch gesehen ein Peptid ist, welches aus mehreren () Aminosäuren. "The role of steroid and peptide hormones in the regulation of blood pressure and electrolytes" - Abschieds-Symposium zu Ehren von Prof. Dr. Wolfgang Oelkers. Steroidhormone: lipidlöslich - können die Zellmembran direkt passieren > aktivieren Enzyme oder Ionenkanäle > binden dann an spezifische.