Peptides

Substrate peptide for Scr, tyrosine kinase, for use in in vitro assays for Src activity.Src is a member of the Src Family tyrosine Kinases (SFKs), a large cytosolic, non-receptor, kinase family that controls multiple signalling pathways in animal cells. Src is a tyrosine kinase proto-oncogene and elevated levels of Src protein are seen in different tumours including: breast- lung- thyroid- glioblastoma- colorectal- pancreatic- prostate- gastric- biliary tract and skin cancer. Src levels are often associated with tumour progression, metastasis, and a poor clinical outcome and therefore Src has been investigated as a therapeutic target.Peptide is labelled with an N-terminal 5-carboxyfluorescein (5-FAM), a widely used green fluorescent tag.

Vasoactive intestinal peptide (VIP) is a neuropeptide found throughout the body and the central nervous system. VIP is located within cell bodies and nerve endings of the enteric nervous system, brain and pancreas. VIP neurons in the peripheral system fire to regulate blood vessels, and the  CNS innervate cerebral vasculature. VIP  binds to G protein-coupled receptors VPAC1 and VPAC2. VIP and VPAC2 are detected in circular smooth muscle cells of cerebral arterioles. VIP and VPAC1 are also found in lymphatic tissue. VIP can block inflammation, modify the Th response favouring Th2 and induce regulatory T cells. Overexpression of each receptor has been linked to various cancers.VIP administration leads to pancreatic bicarbonate-rich fluid secretion but not to the same degree stimulated by secretin. VIP stimulates insulin secretion in a glucose-dependent manner and also stimulates glucagon secretion. Studies have found that in morbidly obese patients, VIP levels are lowered and work to slow gastric and duodenal motility but increase gastric emptying. Therefore, decreasing VIP levels in obese patients may increase weight gain by accelerating gastric emptying.VIP has been well studied in pancreatic acini. VIP is a full agonist of amylase secretion and increases cyclic AMP synchronised with an increase in intracellular Ca2+ triggered by stimuli that act through cholecystokinin (CCK) or cholinergic agonists. Most cAMP increases and amylase secretion appears to be mediated via VPAC1.

The Influenza Virus Nucleoprotein (311 - 325) is a component of the viral ribonucleotide complex, derived from the influenza virus and it is involved in viral replication, RNA packing and nuclear trafficking. As a monomer it contains basic residues which allow it to bind to single stranded RNA and through its flexible tail loop it has the ability to form NP oligomers.Furthermore NP is able to support the viral polymerase structurally, through associating with the two subunits PB1 and PB2, and it allows the viral ribonucleotide complex to be transported in and out of the nucleus due to its nuclear localisation and nuclear export signals.During influenza viral replication messenger RNA, viral genome RNA and complementary positive-sense RNA are produced and NP is crucial for this replication.Inhibitors of NP have potential to be used to prevent the influenza virus in humans.

The development of type I diabetes occurs when auto-aggressive T cells are not controlled by T regulatory cells and are allowed to destroy pancreatic islet cells. This ultimately eliminates the production of insulin within the body.  A more precise understanding of the regulatory T cell's antigen specificity by using antigens can provide significant clinical insights into the development of long-term diabetes. The proinsulin 90-104 fragment was used to test antigen-specific T-cell responses in type I diabetes CD4+ T cells. This peptide has helped show that the development of diabetes is linked to an increase in proinsulin-specific T regulatory cells, which may be regulating the rise in auto-aggressive T cells. Further work with the proinsulin 90-104 peptide could help design novel antigen-specific therapy.

Histone H3 (1-20)-GG-[Lys(5-FAM)] is derived from Histone 3 (H3) which 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. Both H4 and H3 are highly conserved and perform roles in binding to segments of DNA which enter and leave the nucleosome and in chromatin formation. 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. Due to histones containing a large number of lysine and arginine residues they have a positive net charge which interacts in an electrostatic manner with the negatively charged phosphate groups in DNA. 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.Histone H3 (1-20)-GG-[Lys(5-FAM)] has a C-terminal GKK linker labelled with 5-Carboxyfluorescein (5-FAM), a widely used green fluorescent tag. This peptide also has an uncharged C-terminal amide.

The ionic-complementary octapeptide, FEFEFKFK, can self-assemble into antiparallel β-sheet rich fibres and forms very stable hydrogels when at a concentration of more than 20 mg/mL (in water).These peptide hydrogels are naturally biocompatible and biodegradable and can be metabolised by the body. Such hydrogels have been shown to mimic the structure of the extracellular matrix, thus offering cells a niche to undertake their physiological functions. These properties mean that these hydrogels have the potential for use in medical applications.FEFEFKFK hydrogels are able to support the culture of cells such as mesenchymal stem cells in three dimensions with sustained cell viability. They can also support the differentiation into osteoblasts and promote mineralisation upon addition of osteogenic stimulation. They therefore have potential for use in the regeneration of hard tissues such as alveolar bone following injury or degeneration.

Peptide H-FQDGDLTLYQSNTILR^-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.