PEG-MGF

What is PEG-MGF?

PEG-MGF is the PEGylated form of mechano growth factor, the 24-residue E-domain peptide of the IGF-1Ec splice variant of insulin-like growth factor 1, sequence Tyr-Gln-Pro-Pro-Ser-Thr-Asn-Lys-Asn-Thr-Lys-Ser-Gln-Arg-Arg-Lys-Gly-Ser-Thr-Phe-Glu-Glu-His-Lys, written YQPPSTNKNTKSQRRKGSTFEEHK. The unmodified peptide has a molecular weight of approximately 2866 g/mol; the PEGylated conjugate supplied here runs at roughly 9.8 kDa, and as a conjugate rather than a discrete small molecule it carries no CAS registry number on this listing. The splice variant itself was cloned from rabbit muscle subjected to mechanical stretch by Yang, Alnaqeeb, Simpson and Goldspink (J Muscle Res Cell Motil, 1996), which is where the mechano growth factor name originates. One point of nomenclature matters to experimental design: MGF refers in the literature both to the full-length IGF-1Ec splice-variant protein and, in the peptide literature, to its C-terminal E-domain peptide alone. PEG-MGF is the latter, conjugated to polyethylene glycol. The PEGylation rationale is pharmacokinetic: the unmodified E peptide is cleared within minutes, and conjugation of polyethylene glycol increases hydrodynamic radius, reduces renal filtration and slows proteolytic degradation, the standard logic of the field reviewed by Harris and Chess (Nat Rev Drug Discov, 2003). Supplied as lyophilised powder for in-vitro laboratory research use only, not a licensed medicine anywhere.

PEG-MGF vs MGF

The two entries in this catalogue contain the same 24-residue E-domain peptide, YQPPSTNKNTKSQRRKGSTFEEHK; what separates them is the polyethylene glycol. The unmodified MGF E peptide is the molecule that appears throughout the primary literature, from the myoblast proliferation work of Yang and Goldspink (FEBS Lett, 2002), through the satellite cell activation studies of Hill and Goldspink (J Physiol, 2003), to the human primary muscle culture work of Kandalla and colleagues (Mech Ageing Dev, 2011). It is also the molecule whose clearance limits its utility, since the peptide disappears within minutes, which confines most published work to cell culture or local delivery. PEG-MGF carries the same sequence with polyethylene glycol conjugated to it, raising the mass from roughly 2866 g/mol to approximately 9.8 kDa. The trade is interpretability against residence time. The unmodified peptide maps directly onto the published literature, whereas the PEGylated form does not appear in the primary MGF literature at all, so its behaviour in any given assay is an extrapolation from the unmodified molecule and from general PEGylation pharmacology rather than an established finding. PEGylation also changes assay behaviour in ways that need controlling: the conjugate runs at higher apparent mass on size-exclusion chromatography, the polymer can interfere with antibody-based detection, and conjugation can alter receptor interaction. Researchers choose MGF when fidelity to the published molecule matters, and PEG-MGF when extended exposure is the design priority and the deviation from the literature is accepted as a variable.

PEG-MGF Research Applications

PEG-MGF inherits its research programme from the unmodified E-domain peptide, and every application below is drawn from the unmodified literature, because the PEGylated 24-mer itself has no dedicated peer-reviewed publications. The proliferation line: Yang and Goldspink (FEBS Lett, 2002) reported that the IGF-I Ec peptide stimulates proliferation of C2C12 myoblasts while blocking differentiation, the opposite balance to mature IGF-I, and Ates and colleagues (FEBS Lett, 2007) reported increased progenitor cell numbers in cultures derived from normal, dystrophic and ALS muscle. The satellite cell line: Hill and Goldspink (J Physiol, 2003) showed that the MGF splice variant is expressed as an early pulse after local muscle damage and is associated with satellite (stem) cell activation, and Kandalla and colleagues (Mech Ageing Dev, 2011) reported that the E peptide increased proliferation and delayed senescence in primary human muscle cell cultures from neonatal and young adult donors, though not from old adult muscle. The transplantation line: Mills and colleagues (Am J Transplant, 2007) reported that the E peptide improved myogenic precursor cell engraftment in a mouse model. The honest boundaries: a study conducted at two pharmaceutical companies found no effect of the MGF C-terminal peptide, at concentrations up to 500 ng/ml, on the proliferation or differentiation of C2C12 cells, primary human myoblasts or primary mouse muscle stem cells, and concluded that the physiological role of MGF itself should be questioned (Fornaro et al., Am J Physiol Endocrinol Metab, 2014); human evidence is thin to absent, with no clinical trials; and the field's own review literature describes MGF as a putative repair factor rather than an established one (Matheny, Nindl and Adamo, Endocrinology, 2010). Material supplied here is for in-vitro laboratory research only.

Reconstitution Guide

Allow the vial and the diluent to reach room temperature, then sterilise the rubber stopper of both the peptide vial and the bacteriostatic water vial with an alcohol swab. Slowly draw the bacteriostatic water into a sterile syringe and inject it gently down the inner glass wall of the vial, never directly onto the lyophilised powder. Swirl gently in a slow circular motion until fully dissolved; the solution should be clear and colourless. Never shake or vortex, and avoid vigorous agitation of reconstituted PEG conjugates. The underlying 24-residue sequence contains no methionine, cysteine or tryptophan, so the peptide itself carries no oxidation-prone residues and no disulfide chemistry; the handling consideration is the PEG moiety, which is hydrophilic and fully soluble but turns the conjugate into a polymer-sized species, so it behaves differently from a small peptide in membrane filtration and chromatographic steps. Work under sterile conditions, minimise stopper-open time, label the vial with the reconstitution date and refrigerate immediately.

See our full peptide reconstitution guide and reconstitution calculator for step-by-step protocol.

Storage Instructions

Store lyophilised vials at -20°C, protected from light and moisture, for long-term stability of up to 24 months. Once reconstituted with bacteriostatic water, hold the solution at 2-8°C (standard refrigerator) and use within approximately 4 weeks. For longer storage, prepare single-use aliquots at -20°C and thaw each aliquot only once; repeated freeze-thaw cycles are the fastest route to aggregation, and PEG conjugates are not exempt from this. Keep vials tightly sealed with minimal headspace, protect from light, and never store the solution in contact with oxidising agents or organic solvents. Handle under sterile laboratory conditions throughout, and keep the batch number and certificate of analysis on file for experimental records. For in-vitro laboratory research use only.

Frequently Asked Questions

Research References

• Different roles of the IGF-I Ec peptide (MGF) and mature IGF-I in myoblast proliferation and differentiation (Yang and Goldspink, FEBS Lett, 2002)
• Expression and splicing of the insulin-like growth factor gene in rodent muscle is associated with muscle satellite (stem) cell activation following local tissue damage (Hill and Goldspink, J Physiol, 2003)
• Mechano Growth Factor E peptide (MGF-E), derived from an isoform of IGF-1, activates human muscle progenitor cells and induces an increase in their fusion potential at different ages (Kandalla et al., Mech Ageing Dev, 2011)
• Mechano-growth factor peptide, the COOH terminus of unprocessed insulin-like growth factor 1, has no apparent effect on myoblasts or primary muscle stem cells (Fornaro et al., Am J Physiol Endocrinol Metab, 2014)

Related Research Compounds

• → MGF 2mg
• → IGF-1 LR3
• → TB-500
• → Bacteriostatic Water 10ml