Produits biochimiques et réactifs

<p>The HE4 antibody is a highly specific monoclonal antibody used in the field of Life Sciences. It is designed to bind to a specific antigen and can be used for various applications, including research and diagnostics. This antibody is produced by hybridoma cells, which are created by fusing mouse spleen cells with myeloma cells. The resulting monoclonal antibody has a high affinity for its target antigen and can be used in various immunoassays.</p>

<p>Highly purified native Human RBP protein</p>

<p>Collagen type I antibody was raised in rabbit using collagen type I from human and bovine placenta as the immunogen.</p>

<p>Mouse monoclonal CKMB antibody (MM subunit)</p>

<p>Goat anti-rat IgM (Rhodamine) was raised in goat using rat IgM mu chain as the immunogen.</p>

<p>The HbA1c antibody is a mouse monoclonal antibody that specifically binds to the HbA1c protein. This antibody is commonly used in Life Sciences research to study the role of HbA1c in various biological processes. It can be used to detect and quantify HbA1c levels in blood samples, making it a valuable tool for monitoring diabetes and glycemic control. It does not cross react with HBA1O.</p>

<p>Complement C4 antibody was raised in goat using human C4 complement as the immunogen.</p>

<p>TSH antibody was raised in goat using human TSH as the immunogen.</p>

<p>Adenovirus antibody (FITC) was raised in mouse using hexon group antigen of many ADV serotypes as the immunogen.</p>

<p>The GATA1 antibody is a polyclonal antibody that is used in the field of Life Sciences. It is designed to target and bind to GATA1, a protein involved in the regulation of gene expression during development. This antibody has been shown to be reactive with human serum and can be used for various applications such as immunohistochemistry, Western blotting, and ELISA. The GATA1 antibody is highly specific and sensitive, making it an essential tool for researchers studying the role of GATA1 in various biological processes. Its high affinity for the target protein ensures accurate and reliable results. Whether you are conducting basic research or working on a diagnostic project, the GATA1 antibody is an invaluable tool that will help you advance your scientific endeavors.</p>

<p>The THC antibody is a monoclonal antibody that acts as an inhibitor against the growth factor angptl3. It belongs to the class of antibodies and is specifically designed to neutralize the effects of angptl3. This antibody has been widely used in Life Sciences research and has shown promising results in treating conditions such as thrombocytopenia and alpha-fetoprotein-related disorders. The colloidal nature of this monoclonal antibody allows for easy delivery and precise targeting. Additionally, it has been found to have high affinity towards angptl3, making it an effective tool for studying the role of this growth factor in various biological processes. With its potent inhibitory properties and ability to bind to specific targets, the THC antibody is a valuable asset in biomedical research.</p>

<p>Complement C1q protein is a vital component of the complement system, which is an integral part of the immune response. This protein plays a crucial role in the recognition and clearance of pathogens and damaged cells. Complement C1q protein binds to antibodies that have attached to foreign substances, leading to the activation of the complement cascade. This activation triggers a series of events that result in cell lysis, neutralization of pathogens, and promotion of inflammation. Additionally, Complement C1q protein has been found to interact with various growth factors such as epidermal growth factor (EGF) and transforming growth factor-beta (TGF-beta), modulating their activity. It also participates in collagen synthesis and interacts with other proteins like anti-ACTH antibodies and trastuzumab. With its multifaceted functions, Complement C1q protein plays a pivotal role in maintaining immune homeostasis and defending against infections and diseases.</p>

<p>Purified recombinant p17 Treponema pallidum protein</p>

<p>The Influenza A protein is a recombinant antigen that plays a crucial role in the immune response against influenza viruses. It acts as a target for antibodies and stimulates the production of interferon, which helps fight off viral infections. This protein is commonly used in research laboratories and diagnostic tests to detect and study influenza viruses.</p>

<p>Mouse monoclonal Zika virus envelope antibody</p>

<p>Mouse Monoclonal Ebola Virus VP40 antibody</p>

<p>Streptavidin Poly-HRP80 Conjugate (diluted to 50ug/ml in stabilizer 85R-112)</p>

<p>The hCG alpha antibody is a monoclonal antibody that specifically targets the hormone hCG (human chorionic gonadotropin). This antibody recognizes a specific amino acid sequence in the hCG protein polypeptide and can be used in various applications in the field of Life Sciences. The hCG alpha antibody is produced using transgenic technology, resulting in a high-quality recombinant protein with excellent specificity and affinity.</p>

<p>Purified Mouse IgG2a FITC conjugate</p>

<p>RSV antibody was raised in mouse using fusion protein of RSV, types A and B as the immunogen.</p>

<p>Monkey whole IgM</p>

<p>Myelin oligodendrocyte glycoprotein (MOG) is a member of the immunoglobulin (Ig) protein superfamily and is expressed exclusively in the central nervous system (CNS) on the surface of myelin sheaths and oligodendrocyte processes. MOG is expressed at the onset of myelination, and therefore is a potential marker for oligodendrocyte maturation.MOG contains an extracellular domain, a transmembrane domain, a cytoplasmic loop, a membrane-associated region and a cytoplasmic tail. MOG may function as a cell surface receptor or cell adhesion molecule. Fifteen different alternatively spliced isoforms have been detected in humans. These are present either on the cell surface, the endoplasmic reticulum in the endocytic system, or in secreted form.The secreted form of MOG may trigger autoimmunity if released into the cerebrospinal fluid and periphery. MOG is thought to be a key target for autoantibodies and cell-mediated immune responses in inflammatory demyelinating diseases such as multiple sclerosis (MS) and is therefore widely studied in this field.The MOG (34-56) fragment is in the most potent auto-antigenic region of MOG, and is highly effective at inducing experimental autoimmune/allergic encephalomyelitis (EAE), an animal model that resembles MS. This peptide has an uncharged C-terminal amide.</p>

<p>Reactivity to human leukocyte antigens (HLAs) is a risen concern in clinical treatments such as organ transplant rejection. Understanding the epitopes causing reactivity and the signalling pathways could lead to better clinical therapies. The peptides presented by the non-classical HLA-G are important for a largely tolerogenic role and are considered part of an immune checkpoint. This, therefore, makes understanding ligand characteristics and HLA-G a target for cancer therapies. The HS1 fragment (160-168) has been identified as an epitope that human leukocyte antigen HLA-G naturally presents, determined by liquid chromatographic tandem mass spectrometry (LC-Ms/MS). This epitope has been used extensively in the literature to help understand the natural ligand presentation of HLA-G.For example, leukocyte immunoglobulin (Ig)-like receptors (LILRs) are key regulators of the immune response and therefore targets for therapeutics. Inhibitory LILRB1 and LILRB2 with HLA-G are pivotal for immunotolerance during pregnancy and autoimmune diseases plus cancer cell immune evasion. HS1 fragment (160-168) was used in binding affinity assays to clarify the conformational plasticity of the interaction between the receptor, the HLA antigen, and the various peptides HLA-G can accommodate.</p>

<p>This C-terminal Sortagging peptide acts as a (oligo)glycine nucleophile in the final steps of a sortagging protein labelling reaction. This reaction results in the [Lys(5-TAMRA)]- fluorescent moiety being attached to the C-terminus of the target protein or peptide.A substrate peptide containing the LPXTG motif is recognised and cleaved by the enzyme Sortase A (SrtA) from Staphylococcus aureus. The catalytic cysteine residue in the active site of SrtA, serves as a nucleophile to cleave the peptide bond between threonine and glycine of the substrate peptide. Cleavage results in the formation of a thioacyl intermediate between the substrate peptide and SrtA. This intermediate is then resolved by the N-terminus of this (oligo)glycine nucleophile peptide, resulting in the creation of a new peptide bond that links the substrate peptide to this peptide and its fluorescent dye.  This method of protein labelling is known as sortagging.5-Carboxytetramethylrhodamine (5-TAMRA) is a widely used fluorescent dye which excites at 546 nm and emits at 579 nm.</p>

<p>Peptide H-IQIIPK^-OH is a Research Peptide with significant interest within the field academic and medical research. This peptide is available for purchase at Cymit Quimica in multiple sizes and with a specification of your choice.</p>

<p>CREB is a transcription factor that regulates diverse cellular responses including: proliferation- survival and differentiation- adaptive immune responses- glucose homeostasis- spermatogenesis- circadian rhythms and synaptic plasticity associated with memory. CREB is induced by a variety of growth factors and inflammatory signals and subsequently mediates the transcription of genes containing a cAMP-responsive element, including IL-2, IL-6, IL-10, and TNF-alpha. In the immune system, CREB induces an anti-apoptotic survival signal in monocytes and macrophages, has a role in promoting the proliferation, survival and regulation of T and B lymphocytes and is required for the generation and maintenance of regulatory T cells. CREB also often promotes anti-inflammatory immune responses, such as through the inhibition of NF-KB activity, the induction of IL-10, and the generation of Tregs. These anti-inflammatory responses could be protective by inhibiting unwanted inflammation, tissue damage, and autoimmune responses, or they could be pathogenic in the context of infection and tumour immunosurveillance. Peptide is labelled with an N-terminal 5-carboxyfluorescein (5-FAM), a widely used green fluorescent tag.</p>

<p>Conjugated THC-BSA hapten</p>

<p>Fluorescence resonance energy transfer (FRET) peptide substrate derived from SARS-CoV-2 spike (S) S1/S2 site. This FRET peptide exhibits internal fluorescence quenching when intact, however hydrolysis of the peptide between the donor/acceptor pair generates fluorescence, enabling the quantitative measure of enzymatic activity. The S1/S2 site of SARS-CoV-2 S is efficiently cleaved by a wide range of proteases including furin.SARS-CoV-2 Spike (S) protein is one of the four essential structural proteins from the coronavirus SARS-CoV-2. S protein is a large, class I viral transmembrane protein essential for viral entry into the cell via binding to the host angiotensin-converting enzyme 2 (ACE2) receptor. S assembles as a trimer on the surface of the virion, giving it its distinctive 'corona' or crown-like appearance. The ectodomains of S proteins are divided into two subunits, S1 and S2. S1 helps in host receptor binding and is further divided into two subdomains: N-terminal domain (NTD) and C-terminal domain (CTD), both of which act as receptor-binding domains. The S1 CTD contains the receptor-binding motif (RBM). The S2 subunit accounts for fusion. Peptide contains an N-terminal 5-carboxyfluorescein (5-FAM), a widely used green fluorescent tag and a 2, 4-dinitrophenyl (Dnp) quencher.</p>

<p>Forms of inherited muscular dystrophy such as Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) result from mutations targeting the dystrophin gene. These disorders are X-linked, progressive, and cause the gradual weakening of the muscles leading to respiratory failure and ultimately reduces the patient lifespan.In DMD, mutations lead to the production of premature stop codons and hence the truncated dystrophin protein product is vulnerable to nonsense mediated decay and degradation. Therefore, dystrophin production in muscle cells is reduced. On the other hand, nonsense mutations which also contribute to DMD, cause exon skipping in BMD and result in an internally truncated protein product which are partially functional. The symptoms of BMD are later onset compared with DMD which develop in patients between 2 to 7 years.Treatments of dystrophin disorders are in clinical trial including antisense oligonucleotide exon skipping and gene therapy. However, the efficacies of these treatments are not easily quantified. Currently levels of muscular dystrophin are quantified by western blot which can be unreliable. The peptide provided here, aligning residues dystrophin (2690-2700), has been tested via western blot, mass spectrometry, immunostaining and RT-PCR to try and provide the most robust method of validation of dystrophin levels possible. Further study with this dystrophin fragment could prove to be a vital step in the understanding and treatment of dystrophin disorders. Within our catalogue we also have other peptides tested for dystrophin quantification available plus the full-length dystrophin protein.</p>

<p>C-type natriuretic peptide (CNP) is expressed from numerous tissue types but primarily within the central nervous system and the bone. CNP binds the natriuretic peptide receptor B (NPR-B) and acts as an autocrine/paracrine factor. CNP signalling acts as a positive regulator of endochondral bone growth. Both CNP and NPR-B are being explored as therapeutic targets for growth disorders including achondroplasia. CNP (1-22) is the major form of CNP found in the plasma. Exogenous CNP (1-22) can be cleared quite effectively, administration of a constant 'high' dose was able to overcome this obstacle to induce endochondral ossification and accelerated bone growth. However, CNP (1-22) may have the potential to induce systemic vascular resistance and blood pressure issues which would need to be addressed before future clinical applications. Researchers are trying to better establish the function and role of CNP (1-22) one strategy has been the addition of conjugates, such as the C-terminal of ghrelin, to try and improve the clinical efficacy.</p>

<p>This peptide is recognised and cleaved by the enzyme Sortase A (SrtA) from-Staphylococcus aureus. The catalytic cysteine residue in the active site of SrtA, serves as a nucleophile to cleave the peptide bond between threonine and glycine. Cleavage results in the formation of a thioacyl intermediate between the peptide and SrtA. This intermediate is then resolved by the N-terminus of an (oligo)alanine residues as acyl acceptors, resulting in the creation of a new peptide bond that links the peptide and its biotin tag to the incoming nucleophile.- This method of protein labelling is known as sortagging.This peptide contains an C-terminal biotin tag for detection and purification.</p>

<p>Orexin B is one of two closely related peptides- the orexins (also known as hypocretins). These small neuropeptides are secreted from orexin-containing neurons, located mainly in the lateral hypothalamus (LH). Orexins function via the binding and activation of two G-protein-coupled receptors (GPCRs)- orexin receptor type 1 (OX1) and 2 (OX2).[Ala(11), D-Leu(15)]orexin-B is a highly potent and selectiveOX2 receptor agonist which can discriminate between the OX1 and OX2 receptors, with a 400-fold selectivity for the OX2 over OX1. [Ala(11), D-Leu(15)]orexin-B is therefore a beneficial tool for addressing the functional roles of OX2.The L-leucine residue at position 11 of orexin B is important for selectivity to OX2 over OX1. L-Alanine substitution at position 11 and D-leucine substitution at positions 15 maintain the potency of orexin-B to OX2, while significantly reducing the potency for OX1.Orexins play several vital roles in a range of physiological activities, including: circadian rhythm- feeding behaviour- energy balance- glucose metabolism- neuroendocrine functions- stress-adaptive responses and reward and addiction. Orexins have also been linked to the pathological processes of neurological diseases such as: narcolepsy- depression- ischemic stroke- drug addiction and Alzheimer's disease.</p>

<p>Apolipoprotein A-I enables the efflux of fat molecules from within cells as high-density lipoprotein (HDL) particles for transport back into LDL particles or to the liver for excretion. HDLs are one of five major groups of lipoproteins. Increasing concentrations of HDL particles are strongly associated with decreasing accumulation of atherosclerosis within the walls of arteries. Apolipoprotein A-I is often used as a biomarker for prediction of cardiovascular diseases, such that low levels of APOA1 are associated with an increased risk of adverse events in patients with coronary artery disease. In such cases, APOA1 can be used as a biomarker to predict cardiovascular disease progression.</p>

<p>Ovalbumin (OVA) is the primary protein in egg-white, and is involved in initiating food allergies and asthma. It is a highly immunogenic protein and can be used for peptide conjugation in the development of antibodies.OVA (371-382) is a class I (Kb)-restricted peptide epitope of OVA. The ovalbumin fragment is presented by the class I MHC molecule, H-2Kb.</p>

<p>Bovine myeloid antimicrobial peptide-27 (BMAP-27) belongs to the cathelicidin family of peptides which displays rapid bactericidal activity against Staphylococcus aureus, Streptococcus uberis, and Escherichia coli. Cathelicidins belong to the large group of cationic peptides with amphipathic properties and have an important role in the mammalian innate immune system. BMAP-27 is cytotoxic to human erythrocytes and neutrophils, although at higher than microbicidal concentrations. It has a potential for the treatment of bacterial infections in individuals with cystic fibrosis-associated lung infections.</p>

<p>Galanin (1-30) (human) is an endogenous neuropeptide with endocrine, metabolic and behavioural effects. Galanin has a role in intestinal smooth muscle contraction, insulin and somatostatin release, and synaptic neurotransmission.Galanin is widely distributed in the central nervous, peripheral, and endocrine systems. Galanin's overarching function is as an inhibitory, hyper-polarizing neuromodulator for classical neurotransmitters like acetylcholine and serotonin. Galanin interacts with 3 receptor subtypes, GalR1-3 G protein-coupled receptors inserted into the plasma membrane. GalR1 is believed to activate a Gβγ pathway to regulate MAPK activation. GalR2 can also activate the MAPK pathway, but unlike GalR1, there is detectable inositol phosphate production. GalR3 is associated with the Galphai/o pathway. Activation of the receptor leads to a cellular influx of K+. Each receptor has been associated with neurological diseases such as GalR3 and epilepsy.Galanin protects against various physiological insults in vitro, including excitotoxicity and β-amyloid toxicity. Changes in galanin have been widely studied concerning Alzheimer's disease, and galaninergic neurons are spared in late-stage Alzheimer's relative to non-galaninergic neurones.Galanin (1-30) has been used as an agonist for the GalR2 receptor in vitro for calcium mobilisation assays to understand the role Galanin/GalR2 play in multiple sclerosis.Galanin (1-30) is provided with an N-terminal 5-TAMRA, a widely used red fluorescent reagent ideal for peptide labelling and detection. The excitation/emission for this reagent is 555 nm/580 nm.</p>

<p>Portion of EBV EBNA 3</p>

<p>Galanin is a widely distributed neuropeptide in the central nervous system (CNS), peripheral regions and endocrine system. Galanin interacts with 3 receptor subtypes, GalR1-3 G protein-coupled receptors inserted into the plasma membrane. Galanin has a role in energy homeostasis. Central injections of galanin to the amygdala led to food intake in rats. Galanin also acts in the CNS to inhibit neurotransmitter release, such as acetylcholine. Galanin has been implicated in numerous neurological conditions, including Alzheimer's disease, depression, and epilepsy. A better understanding of the galinergic signalling pathways may uncover a source for therapeutics for conditions such as epilepsy.Unlike human galanin, full-length porcine galanin contains only 29 amino acids and is C-terminally amidated. The first 15 residues are still highly conserved.  The best-recognized effect of galanin on the endocrine pancreas is the inhibition of insulin secretion in vitro and in vivo on multiple model systems, including rats, dogs, and mice. However, the same effect cannot be achieved at the same concentrations in human models with infusions of porcine galanin. Structural activity and point mutation studies show that the N-terminal (1-15) fragment is vital for the interaction/activation of the GAL receptor and the inhibition of insulin secretion.</p>

<p>Region of SDF1 protein corresponding to amino acids KPVSLSYRCP CRFFESHVAR ANVKHLKILN TPNCALQIVA RLKNNNRQVC IDPKLKWIQE YLEKALNKRF KM.</p>

<p>The SARS-CoV-2 spike protein is present on the outside of the virus particles and can bind to angiotensin-converting enzyme II (ACE2) present on the host cells. The C-terminal receptor binding domain (RBD) of the spike protein binds to the N-terminal peptidase M2 domain of ACE2. This receptor binding results in the internalisation of the virus-receptor complex and is, therefore the mechanism of entry of SARS-CoV-2 into host cells.The spike protein residues LIDLQELGKY (1197-1206) have been identified as a T-cell epitope with a predicted HLA restriction. Immune targeting of confirmed epitopes may potentially offer protection against SARS-CoV-2 and help the development of vaccines for long-lasting immunity.</p>

<p>Proinsulin connecting peptide (C-peptide), links the A and B chains of proinsulin. Upon enzymatic cleavage of C-peptide from pro-insulin in the pancreas, C-peptide is released into the blood stream along with insulin (A- and B-chains bonded together) in equimolar quantities. C-peptide can influence a wide variety of physiological conditions linked to diabetes, such as neuropathy, nephropathy, and encephalopathy. C-peptide is able to ameliorate and reverse the degrading effects of neuropathy in diabetes.</p>

<p>The LDVP peptide (CS1), located in the type III connecting segment (V-region) of fibronectin, exhibits cell binding properties thus contributing to the adhesion of fibronectin to other cells.</p>

<p>Histone 3 (H3) is one of the four core histones (H2A, H2B, H3 and H4) fundamental in compacting eukaryotic DNA into the nucleosome. The nucleosome arises when 147 base pairs of DNA wrap around a H3-H4 tetramer and two H2A-H2B dimers, forming the histone octamer core. Similar to the other core histone, H3 has a globular domain and a flexible N-terminal domain, 'histone tail' which can undergo modifications such as acetylation, methylation, phosphorylation and ubiquitination. The transcriptional activation or silencing of the chromatin is controlled by ATP-dependent chromatin remodelling factors and histone modifying enzymes which target histone proteins. Both processes function to alter the positioning of the nucleosome, allowing the DNA it to be either available or inaccessible to the transcription machinery.The lysine at position 4 of this peptide has been tri-methylated and it is implicated in studies that this modification may remodel the chromatin so that it is more accessible to transcription factors, which may ultimately increase the level of gene expression. Moreover, the serine at position 10 has been phosphorylated, and studies have suggested that this may induce chromatin condensation, and subsequently repress transcription and gene expression.Histone H3 (1-20) K4Me3, pS10-GG-[Lys(5-FAM)] has a C-terminal GKK linker labelled with 5-Carboxyfluorescein (5-FAM), a widely used green fluorescent tag.</p>

<p>This sequence corresponds to the peptide bond between mammalian Lys33- (K33) linked Ub proteins- where (GG) corresponds to the C-terminus of the side chain appended Ub.Lys33-linked polyUb chains are assembled by the HECT E3 ligase AREL1. K33-linked polyUb chains have been linked to DNA damage response and in the regulation of innate immunity. Ubiquitination with K33-linked chains also regulates T-cell receptor function and contributes to the stabilization of actin for post-Golgi transport.</p>

<p>Peptide H-I^DAL^NENK-OH is a Research Peptide with significant interest within the field academic and medical research. This peptide is available for purchase at Cymit Quimica in multiple sizes and with a specification of your choice.</p>

<p>Peptide derived from the Vitamin D-binding protein which binds to circulating vitamin D metabolites produced from UV-B exposure or when it is ingested in the diet. The leucine residue at position 2 is isotopically labelled with carbon-13(6) and nitrogen-15(1).</p>

<p>Myocarditis is an inflammatory heart disease often associated with a previous viral infection. Evidence has suggested that myocarditis may be due to autoimmune responses directed against cardiac tissue. The inflammatory immune response caused after infection may break tolerance by mechanisms of molecular mimicry, bystander activation, and loss of immune regulation. Experimental autoimmune myocarditis (EAM) is a model of inflammatory heart disease generated by immunizing susceptible rats or mice with cardiac myosin or its myocarditic epitopes. In the EAM model, cellular infiltrates consist primarily of T cells and macrophages, and T lymphocytes responsive to cardiac myosin can transfer disease. Cardiac myosin is a large peptide, which is composed of two H chains and two pairs of L chains. Proteolysis of myosin yields three subfragments including a globular head or subfragment 1 (S1) region, an alpha helical coiled coil rod comprised of subfragment 2 (S2), and light meromyosin (LMM). In the Lewis rat, the S2 subfragment has been shown to produce the most severe myocarditis.</p>

<p>Amino acids 487-496 of Poly(ADP-ribose) polymerase 1 (PARP1). PARP1 is a nuclear DNA repair enzyme that binds to DNA when damage is detected. PARP1 coordinates double and single strand break repair by first cleaving NAD+ into nicotinamide and ADP-ribose, and then synthesising poly-(ADP-ribose) (PAR) chains from ADP-ribose on target proteins (PARylation). PARylation of histone proteins mediates relaxation of the chromatin and recruitment of DNA-break repair enzymes.PARP1 can also act as a transcriptional co-activator, modulating the expression of itself and many other genes by direct binding to or PARylation of enhancers and promoters. PARP1 is also involved in maintaining mtDNA.PARP1 belongs to the PARP family which has 7 known and 10 putative members. PARP1 accounts for &gt;85% of the PARP activity in cellular systems.</p>

<p>Protease activated receptors (PARs) are a distinctive four-member family of seven transmembrane G protein-coupled receptors (GPCRs) widely expressed in inflammatory cells. PARs are cleaved by certain serine proteases to expose a tethered ligand domain, this ligand domain then binds to and activates the receptors to initiate multiple signalling cascades. These PAR-activating proteases therefore represent PAR agonists. This PAR-2 agonist peptide mimics the sequence of the 'tethered ligand' and is therefore capable of activating the receptor independently of N-terminal proteolysis.SLIGRL-NH2 inhibits the development of airway eosinophilia, hyper-responsiveness and displays bronchodilator activity in allergic mice and also facilitates gastrointestinal transit in mice-in vivo.PAR activation has been linked to inflammation, therefore compounds that mimic or interfere with the PAR-activating processes are attractive therapeutic candidates.</p>

<p>Palmitoyl GQPR tetrapeptide.</p>