0 Shop now

Author: peptidpeti

  • GHK-Cu Copper Peptide: Molecular Reference (CAS 49557-75-7)

    GHK-Cu is one of the most studied copper-binding peptides in laboratory research. This reference page collects its core molecular data and describes, strictly in an in-vitro context, why it is used as a research material. No human or therapeutic use is described or implied.

    Identity and molecular data

    • Name: GHK-Cu — the glycyl-L-histidyl-L-lysine copper(II) complex
    • Peptide sequence: Gly-His-Lys (GHK), a tripeptide
    • CAS number (copper complex): 49557-75-7
    • Free peptide formula: C₁₄H₂₄N₆O₄ (GHK), molecular weight approximately 340.4 g/mol
    • Copper(II) complex: commonly reported molecular weight approximately 403.9 g/mol

    The peptide portion is a short sequence of glycine, histidine and lysine; the histidine and terminal amine provide the coordination site that binds copper(II), giving the characteristic blue complex.

    Why it is used as a research material

    GHK-Cu is used in vitro as a defined copper-delivery tripeptide in connective-tissue, fibroblast and skin-model research, and in studies of copper coordination chemistry. As a research reagent it offers a well-characterised, reproducible way to introduce a copper-peptide complex into a defined experimental system. This page describes areas of laboratory study only and makes no claim about outcomes or efficacy.

    Handling and quality

    Like other lyophilized peptides, GHK-Cu should be stored cold, dry and away from light, and reconstituted using an appropriate solvent under aseptic technique. Each research batch should be supplied with a certificate of analysis confirming identity and >99% HPLC purity — see our COA guide.

    Browse the research-grade GHK-Cu product page or more molecular references in the Peptide Science section.

    For research use only. Supplied strictly for in-vitro laboratory and research purposes and not for human or animal consumption. Nothing here describes or implies any therapeutic use.

  • What “For Research Use Only” Means for Peptides in the EU

    Research peptides are frequently labelled and sold “for research use only” (RUO) and “not for human or animal consumption.” These are not marketing phrases; they describe a specific category of material and carry real obligations for anyone buying or handling it. This article explains, in general terms, what RUO status means in a European context. It is background information for laboratory users, not legal advice.

    Research reagent, not a medicine

    The core distinction is between a research reagent and a medicinal product. Medicinal products intended for people are subject to authorisation and strict manufacturing, labelling and pharmacovigilance requirements before they can be marketed for human use. An RUO reagent sits outside that framework precisely because it is supplied only as a material for in-vitro laboratory investigation, and makes no medical, diagnostic or therapeutic claim.

    What RUO labelling signals

    An RUO designation indicates the material is intended for laboratory research, has not been evaluated or approved for use in or on humans or animals, and is not a diagnostic device. It should be handled by trained personnel under appropriate laboratory controls, and it should never be administered to people or animals.

    Documentation that should accompany RUO material

    Reputable suppliers provide a batch-specific certificate of analysis confirming identity and purity, and a safety data sheet (SDS) describing safe handling. Keeping this documentation on file supports traceability and good laboratory practice. You can read how to interpret the COA in our guide to reading a peptide certificate of analysis.

    Responsibility sits with the end user

    Because RUO material is supplied strictly as a research reagent, the responsibility for using it lawfully and only for legitimate in-vitro research rests with the purchaser and their institution. Treating the RUO boundary seriously is both a compliance matter and simply good scientific practice.

    More background is collected in the Compliance & Regulatory section.

    For research use only. All products referenced are intended strictly for in-vitro laboratory and research purposes and are not for human or animal consumption. This article is general information and not legal advice.

  • Storage and Stability of Lyophilized Research Peptides

    Lyophilized research peptides are stable compounds when stored correctly, but they are sensitive to moisture, heat and light. Getting storage right is what preserves the >99% HPLC purity stated on the batch certificate of analysis through to the day the material is actually used in an experiment. This guide covers storage of both the dry powder and the reconstituted stock, in an in-vitro laboratory context.

    Storing the lyophilized powder

    In dry, lyophilized form most research peptides are best kept frozen for long-term storage, commonly at around -20°C, and colder (-80°C) for extended periods. For short handling windows, 2-8°C is generally acceptable. The three enemies are moisture, heat and light, so keep vials sealed, desiccated and away from direct light. Allow a vial to reach room temperature before opening to prevent condensation from drawing moisture into the powder.

    Storing reconstituted stock solutions

    Once dissolved, a peptide is far less stable than in dry form. Reconstituted stock is normally refrigerated at 2-8°C and used within a limited window that depends on the peptide and the solvent. To avoid repeated freeze-thaw cycles, which accelerate degradation, divide the stock into single-use aliquots and freeze those that will not be used soon.

    Freeze-thaw and aliquoting

    Every freeze-thaw cycle stresses a peptide in solution. The practical rule is to aliquot once, then thaw only what each experiment needs. Label aliquots with the peptide, concentration, solvent and date so the material stays traceable to its original batch.

    Signs to check before use

    Inspect reconstituted solutions for cloudiness or precipitate, and dry powder for any change from the white to off-white appearance described on the COA. Anything unexpected is a reason to re-check handling and storage history before the material enters an assay.

    Always follow the specific storage recommendation printed on the product’s batch documentation. Related guidance is collected in the Storage & Stability section, and the COA guide explains the purity and identity figures storage is meant to preserve.

    For research use only. All products referenced are intended strictly for in-vitro laboratory and research purposes and are not for human or animal consumption. Nothing in this article describes or implies any therapeutic use.

  • Bacteriostatic vs Sterile Water: Choosing a Reconstitution Solvent

    Reconstitution is the step where a lyophilized (freeze-dried) research peptide is dissolved into a liquid stock solution for in-vitro work. The choice of solvent affects both how well the peptide dissolves and how long the resulting stock can be kept. Two options come up most often in the laboratory: sterile water and bacteriostatic water. This article explains the difference in a strictly research context.

    Sterile water for injection (WFI)

    Sterile water contains no additives. It is suitable when a stock solution will be prepared and used immediately, or when any preservative would interfere with a downstream assay. Because it contains nothing to inhibit microbial growth, an opened vial is treated as single-use under good aseptic practice.

    Bacteriostatic water

    Bacteriostatic water contains roughly 0.9% benzyl alcohol as a preservative. The preservative suppresses microbial growth, which is why it is used when a stock solution needs to be drawn from over several days in a research workflow. The trade-off is that benzyl alcohol can interfere with certain sensitive cell-based assays, so its compatibility with the specific experiment should be confirmed first.

    When neither is ideal

    Some peptides are poorly soluble in water. In those cases researchers commonly reach for a small volume of dilute acetic acid (for peptides that dissolve better under mildly acidic conditions) or a minimal amount of DMSO for hydrophobic sequences, followed by dilution into the working buffer. Always check the peptide’s solubility notes before selecting a solvent, and confirm the final solvent is compatible with the assay.

    Aseptic technique matters more than the label

    Whichever solvent is chosen, technique determines whether a stock stays usable: wipe septa with alcohol, introduce the solvent slowly down the vial wall rather than directly onto the peptide cake, swirl gently instead of shaking, and let the peptide dissolve fully before use. Record the solvent and concentration in the lab notebook so results remain traceable.

    For accurate concentrations, base your calculation on the net peptide content from the batch certificate of analysis rather than the gross fill weight — see how to read a peptide COA. More technique guides are collected in the Lab Techniques section.

    For research use only. All products referenced are intended strictly for in-vitro laboratory and research purposes and are not for human or animal consumption. Nothing in this article describes or implies any therapeutic use.

  • How to Read a Peptide Certificate of Analysis (COA)

    A certificate of analysis (COA) is the most important document that ships with any research peptide. It is the batch-specific record of what a vial actually contains: its identity, its purity, and how much of the net mass is peptide rather than water or counterions. In laboratory work, where reproducibility depends on knowing exactly what went into a buffer, reading a COA properly is a core skill. This guide walks through every section of a typical peptide certificate of analysis and explains what each value means for in-vitro research.

    What is a peptide certificate of analysis?

    A COA is a quality-control report issued for a specific manufacturing lot. Unlike a generic product description, it is tied to a batch number and reflects analytical tests performed on that exact batch. A meaningful COA is therefore batch-specific: the same product manufactured on two different dates will carry two different certificates. If a supplier offers only a single static COA for every lot, that is worth questioning.

    At minimum, a research-grade peptide COA should report identity, chromatographic purity, molecular-mass confirmation, net peptide content, physical appearance, and storage guidance, together with the batch number and test dates.

    Identity: mass spectrometry confirmation

    The identity section confirms that the molecule in the vial is the peptide named on the label. This is almost always established by mass spectrometry, commonly electrospray ionization (ESI-MS) or matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF).

    The certificate lists a theoretical mass, calculated from the amino-acid sequence, and an observed mass, measured on the instrument. For most research peptides the two should agree to within about one unit for the average mass. A close match confirms the primary structure; a discrepancy can indicate a truncated sequence, incomplete deprotection, or an unexpected modification. When you review a COA, check that the observed mass is reported as an actual number rather than simply marked “conforms”.

    Purity: reading the HPLC chromatogram

    Purity is the figure most researchers look at first, and it is measured by reversed-phase high-performance liquid chromatography (RP-HPLC). A small amount of peptide is dissolved and passed through a C18 column under a water/acetonitrile gradient, usually with 0.1% trifluoroacetic acid as an ion-pairing agent, while the eluate is monitored by UV absorbance around 214 to 220 nm, where the peptide bond absorbs.

    On the chromatogram the peptide appears as a main peak, and purity is reported as the area percentage of that peak relative to the total area of all peaks. A value of “greater than 99% by HPLC” means the main peak accounts for more than 99% of the total UV-absorbing material, with impurities such as related sequences, deletion products, or residual reagents making up the remainder.

    When reading the trace, look for a single sharp, symmetrical main peak, a flat baseline, and only small satellite peaks. A broad or tailing peak, or several sizeable neighbouring peaks, points to a less homogeneous preparation. The retention time indicates where the compound eluted under those specific conditions and is mainly useful when comparing batches run on the same method.

    Net peptide content: why gross mass is not peptide mass

    This section is the most frequently overlooked, and it bears directly on experimental accuracy. A lyophilized peptide is not 100% peptide: the dry mass also includes bound water and counterions carried over from synthesis and purification, so the net peptide content, the fraction of total mass that is actually peptide, is typically in the range of roughly 70 to 90%.

    Suppose a vial is labelled 10 mg but net peptide content is 80%. The vial then holds about 8 mg of peptide and roughly 2 mg of water and salts. If you calculate a stock concentration from the labelled 10 mg, your true molarity will be about 20% low. For any quantitative in-vitro assay, base solution preparation on the net peptide content, not the gross fill weight.

    Counterions and water content

    Peptides are usually isolated as salts, so a COA may report the counterion, commonly acetate or trifluoroacetate, because the salt form contributes to non-peptide mass and, in some assays, residual TFA is undesirable. Water content is often measured by Karl Fischer titration. Together, counterion and water content account for the gap between gross mass and net peptide content described above.

    Appearance, solubility and physical description

    A COA typically records the physical appearance, most often a white to off-white lyophilized powder or cake, and may add a solubility note indicating the solvent used for testing. A colour or form that departs from the description can signal a handling or storage problem and is worth querying before use.

    Batch number, dates and storage

    The administrative fields tie the document to a physical lot: the batch or lot number, the manufacturing or test date, and recommended storage conditions. Lyophilized research peptides are generally kept cold and protected from light and moisture, and the certificate or accompanying documentation should state the specific recommendation. Record the batch number in your lab notebook alongside your results so any later question about material quality can be traced to the exact certificate.

    A quick checklist for evaluating a peptide COA

    • Is the certificate batch-specific, with a lot number and test date?
    • Is identity confirmed by mass spectrometry, with observed and theoretical masses shown as numbers?
    • Is HPLC purity reported as an area percentage, ideally with the chromatogram attached?
    • Is net peptide content stated, so molarity can be calculated accurately?
    • Are counterion and water content reported?
    • Are appearance, storage and batch data all present?

    Working through these points quickly is what separates a verifiable research supplier from an unverifiable one. At Syntide, every batch is supplied with its own certificate of analysis so these values can be checked before material enters an experiment. You can read more about our approach to purity on the Syntide homepage and browse related topics in the Quality & Analysis section.

    For research use only. All products referenced are intended strictly for in-vitro laboratory and research purposes and are not for human or animal consumption. Nothing in this article describes or implies any therapeutic use.