1. Hydrolysis - This is generally a problem in peptides containing Asp (D) in the sequence, which is very susceptible to dehydration to form a cyclic imide intermediate. For example, in the presence of Asp-Pro (D-P) in the sequence, the acid catalyzed formation of cyclic imide intermediate can result to cleavage of the peptide chain. Similarly, in the presence of Asp-Gly (D-G) in the sequence, the cyclic intermediate can be hydrolyzed either into the original Asp form (harmless) or into potentially inactive iso-aspartate analog. Eventually, all of the aspartate form can be completely converted into the iso-aspartate analog. To a lesser extent, sequences containing Ser (S) can also form cyclic imide intermediate that can end up cleaving the peptide chain.
2. Deamidation - This base-catalyzed reaction frequently occurs in sequences containing Asn-Gly (N-G) or Gln-Gly (Q-G) and follows a mechanism analogous to the Asp-Gly (D-G) sequence. The de-amidation (loss of amine) of the Asn-Gly sequence forms a cyclic imide intermediate that is subsequently hydrolyzed to form the aspartate or iso-aspartate analog of Asn. In addition, the cyclic imide intermediate can lead to racemization into D-Asp or D-iso-Asp analogs of Asn, all of which can potentially be inactive forms.
3. Oxidation - The Cys and Met residues are the predominant residues that undergo reversible oxidation. Oxidation of cysteine is accelerated at higher pH, where the thiol is more easily deprotonated and readily forms intra-chain or inter-chain disulfide bonds. Disulfide bonds can be readily reversed by treatment with dithiothreitol (DTT) or tris(2-carboxyethylphosphine) hydrochloride (TCEP). Methionine oxidizes by both chemical and photochemical pathways to form methionine sulfoxide and further into methionine sulfone, both of which are almost impossible to reverse.
4. Diketopiperazine and pyroglutamic acid formation – Diketopiperazine formation usually occurs when Gly is in the third position from the N-terminus, and more especially if Pro or Gly is in position 1 or 2. The reaction involves nucleophilic attack of the N-terminal nitrogen on the amide carbonyl between the second and third amino acid, which leads to the cleavage of the first two amino acids in the form of a diketopiperazine. On the other hand, pyroglutamic acid formation is almost inevitable if Gln is in the N-terminus. This is an analogous reaction where the N-terminal nitrogen attacks the side chain carbonyl carbon of Gln to form a deaminated pyroglutamayl peptide analog. This conversion also occurs in peptide containing Asn in the N-terminus, but to a much lesser extent.
5. Racemization - This term is loosely used to refer to the overall loss of chiral integrity of the amino acid or peptide. Racemization involves the base-catalyzed conversion of one enantiomer (usually the L-form) of an amino acid into a 1:1 mixture of L- and D-enantiomers. This is more of a concern during peptide synthesis, but a much lesser problem in the finished peptide. In addition, this transformation is very hard to detect and difficult to control.

The general ways to prevent or minimize peptide degradation is to store the peptide in lyophilized form at -20oC or preferably at -80oC (if available). If the peptide is in solution, freeze-thaw cycles should be avoided by freezing individual aliquots. Exposure to pH>8 should be avoided. However, if it is necessary to dissolve peptides at pH>8, its exposure should be minimized and solutions should be chilled. Finally, prolonged exposure of lyophilized peptides and solutions (especially at high pH) to atmospheric oxygen should be minimized.

Explore our list of some of the most popular cosmetic peptides standing by. If you have a different cosmetic peptide synthesis requirement in mind, we can custom synthesize any peptide of any quantity or purity.

Service Features

Quantity – mg to kg scale for GMP and non-GMP grade
Purity – Crude to >98%.
Modifications – We offer an extensive list of modifications options for your needs and can help you find the one that’s right for you.
Applicability – Peptides provided by Bio-Synthesis can be integrated into a wide range of applications.
Content – Our peptides come with Mass Spec Analysis, HPLC Profile and Certificate of Analysis. Additional content analysis, such as Amino Acid Analysis, is also offered. GMP Peptides include detailed records for each step of the process.
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Quality Control:

Bio-Synthesis follows stringent guidelines to guarantee our cosmetic peptides surpass the highest of quality expectations. Each batch includes several analytical data sheets corresponding to the specific products.

Angiotensin, a protein, causes blood vessels to constrict, and drives blood pressure up. It is part of the renin-angiotensin system, which is a major target for drugs that lower blood pressure.

Discovery

Angiotensin was independently isolated by two groups and named “hypertensin” in Argentina and “angiotonin” in the United States and was later shown to be an octapeptide 1, 2, 3.

Types

The original angiotensin4 (Angiotensin-1) gives rise to Angiotensin-2 by removal of a C-terminal dipeptide. This reaction is mediated by angiotensin converting enzyme in plasma, liver and nerve tissues. Further removal of the aminoterminal amino acid from angiotensin-2 by an aspartate amino peptidase yields Angiotensin-3 (called also angiotensin (2-8); abbr. Ang (2-8). Removal of the terminal arginine from Angiotensin-3 yields angiotensin-4 (called also Angiotensin-2(3-8); abbr. Ang-2(3-8)). Angiotensin-(1-7) (abbr. Ang (1-7)) is a peptide formed endogenously from either Ang-1 or Ang-2.

Structural Characteristics

The amino acid sequence of horse hypertensin II has been determined by the use of chymotrypsin, the fluorodinitrobenzene method, and stepwise phenylisothiocyanate degradation. The amino acids of hypertensin II are arranged in the following order1: asp-arg-val-tyr-iso-hist-pro-phe.

Related Peptides

Potentiation of the hypotensive effect of bradykinin by angiotensin-(1-7)-related peptides: In a study, the bradykinin potentiating activity and ACE inhibitory activity of several Ang-(1-7)-related peptides was evaluated: Ang-(2-7), Ang-(3-7), Ang-(4-7), Ang-(1-6), Ang-(1-5) and the selective antagonist of Ang-(1-7): D-[Ala7]Ang-(1-7) (A-779). In vivo experiments were performed in freely moving Wistar rats. ACE activity was evaluated by a fluorometric assay in rat plasma using Hip-His-Leu as a substrate. Intravenous injections of Ang-(1-7) (2.2 nmol) transformed the effect of a single dose of bradykinin (1 nmol) into the effect produced by a double dose. A similar bradykinin potentiating activity was demonstrated for Ang-(2-7) and Ang-(3-7). On the other hand, Ang-(1-5), Ang-(1-6), Ang-(4-7) and A-779 did not change the hypotensive effect of bradykinin in doses ranging from 8 up to 25 nmols. The hypotensive effect of bradykinin was increased by intravenous infusion (0.3 ng/min) of Ang-(1-7) > Ang-(2-7) > Ang-(3-7). Conversely, Ang-(1–5), Ang-(1–6), Ang-(4–7) or A-779 did not change the hypotensive effect of bradykinin. ACE inhibition with Ang-(1–7) related peptides occurred in the order: Ang-(2–7) = Ang-(3–7) > Ang-(1–7) [>>] Ang-(1–5) > Ang-(4–7) = Ang-(1–6) = A-779. A-779 in concentrations up to 10-5 M did not change the ACE inhibitory activity of Ang-(1–7). These results suggest that Ang-(1–7), Ang-(2–7) and Ang-(3–7) can modulate bradykinin actions in vivo5.

Mode of Action

The renin-angiotensin system is a central component of the physiological and pathological responses of cardiovascular system. Its primary effector hormone, angiotensin II (Ang II), not only mediates immediate physiological effects of vasoconstriction and blood pressure regulation, but is also implicated in inflammation, endothelial dysfunction, atherosclerosis, hypertension, and congestive heart failure. The myriad effects of Ang II depend on time (acute vs. chronic) and on the cells/tissues upon which it acts. In addition to inducing G protein- and non-G protein-related signaling pathways, Ang II, via AT(1) receptors, carries out its functions via MAP kinases (ERK 1/2, JNK, p38MAPK), receptor tyrosine kinases [PDGF, EGFR, insulin receptor], and nonreceptor tyrosine kinases [Src, JAK/STAT, focal adhesion kinase (FAK)]. AT(1)R-mediated NAD(P)H oxidase activation leads to generation of reactive oxygen species, widely implicated in vascular inflammation and fibrosis. Ang II also promotes the association of scaffolding proteins, such as paxillin, talin, and p130Cas, leading to focal adhesion and extracellular matrix formation. These signaling cascades lead to contraction, smooth muscle cell growth, hypertrophy, and cell migration, events that contribute to normal vascular function, and to disease progression6

Functions

Angiotensin receptors are present in many tissue types, including adrenal cortex, renal glomeruli, heart, hypothalamus, liver, pancreas, pituitary, platelets, renal tubules, uterus and vascular smooth muscle. Two high-affinity receptor subtypes have been identified by radioligand binding with antagonists: losartan (DuP 753/MK954) identifies AT1 receptors; PD123177 and CGP42112A are markers for AT2 receptors. Angiotensin II may be produced locally in tissues outside the humoral system. For example, it is found in the brain, kidney and heart. Within the brain, the heptapeptide angiotensin(1-7) mimics some effects of angiotensin II, but may be formed directly from angiotensin I. Evidence for non-ACE-mediated angiotensin II production has been reported in the heart. Intravascular angiotensin II receptors are implicated in the central release of vasopressin and other hypophyseal hormones, in increasing sympathetic outflow, in the thirst response and, possibly, in cognitive function; in the inotropic and chronotropic effects of angiotensin II on the heart as well as in growth/hypertrophy; in the control of aldosterone release and in the balance between cortisol and aldosterone secretion; and in modulating sodium, chloride and bicarbonate transport within the kidney 7.

Bio-Synthesis is a leading global manufacturer of high quality custom peptides. We have successfully synthesized tens of thousands of synthetic peptides for the biomedical research community, biotechnology and pharmaceutical companies and have consistently met the highest peptide standards of quality, service and technical expertise. As a peptide manufacturer, we also have the capability to perform a wide variety of synthetic peptide chemistries.

We routinely perform difficult custom peptide synthesis such as synthesis of long peptides (>136 mers), peptides containing unusual modifications, cyclic peptides, cosmetic peptides and peptide oligonucleotide conjugates. In addition, Bio-Synthesis has the capacity for large-scale synthesis (>1 kg) or custom GMP peptide production. Our facility is equipped with state-of-the-art peptide synthesizers and, coupled with our experienced peptide chemists, we are able to deliver your custom peptide synthesis products quickly and with high quality (purity of 90-95% is typical).

Each custom peptide synthesis project is carefully analyzed using an in-house, proprietary PEPscan Identifier and is carefully examined by our chemists. Final synthetic peptide products are shipped with detailed quality control documentation including an HPLC trace, Mass Spec, and a Certificate of Analysis. Custom peptide synthesis is carried out using an assortment of state-of-the-art instrumentation in our 20,000 square foot facility. As a custom peptide manufacturer since 1989, we have earned a reputation that speaks for itself. Our turnaround for custom peptide production is rapid. Most custom peptide orders are shipped within 1 to 2 weeks!

Because Bio-Synthesis maintains its own facilities located in Lewisville, Texas, we are able to provide comprehensive oversight to ensure the highest standards of quality. All custom peptides are accompanied with MS and HPLC analyses. Additional analytical data (e.g., sequencing, amino acid analysis) are available upon request.

Peptide Synthesis Capabilities
a) Personalized consultation with experienced peptide and immunology experts
 b) Peptides from 2 to 120 amino acids
 c) Scales from 1mg to multi grams research grade to GMP production
 d) Purities from crude to >98%
 e) Solid and solution phase chemistry
 f) Wide range of peptide modifications
 g) Cyclic peptides
 h) Special modifications including: phosphorylation, fluoroscein, glycosylation,         PEGylation, rhodamine, AMC, pNA, biotin, boronic amino acids, d-amino acids, stable isotopes, EDANS, dabsyl, dansyl, Abz, thiolactic acids, and many others
 i) High throughput synthesis – peptide library design tools
 j) Specialized peptide synthesis: peptide nucleic acid conjugation
 k) Fast, on-time delivery”