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LifeTein peptide FLAG(GS)HA: DYKDDDDK-GGGGS-YPYDVPDYA-NH2 helped discover insulin-like peptide6, Dilp6, in regulating growth in fruit flies Drosophila | LifeTein Peptide Blog

In humans, liver-derived insulin-like growth factor (IGF1) drives postnatal growth. Early childhood infection of E. coli, Campylobacter spp., even asymptomatic, reduces IGF1 level and restricts early-childhood growth. Does the pathogen-induced Toll-like innate

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In humans, liver-derived insulin-like growth factor (IGF1) drives postnatal growth. Early childhood infection of E. coli, Campylobacter spp., even asymptomatic, reduces IGF1 level and restricts early-childhood growth. Does the pathogen-induced Toll-like innate immune signaling contribute to growth restriction? To answer the question, the researchers examined a corresponding pathway in fruit flies.

LifeTein’s Peptide: FLAG(GS)HA

In fruit flies, Dilps (Drosophila insulin-like peptides) drive their growth, for example, the growth rate of imaginal discs which give rise to adult structures such as wings. Dilps share homology with insulin and IGF1, and they bind to the insulin receptor. Dilp6 is produced by fat body, an organ for nutrient storage and immune functions.

The researchers found Dilp6 is a selective target of Toll signaling in the fat body, an innate immune response from bacterial infections. They also found that Toll signaling reduces Dilp6 transcripts, and dramatically suppresses circulatory Dilp6 levels, and restricts whole-body growth. Restoring Dilp6, on the other hand, rescues growth and viability in fruit flies even with active Toll signaling.

LifeTein’s peptide FLAG(GS)HA was used as a standard in ELISA to quantify Dilp6 in fruit fly hemolymph samples. Here, Dilp6 was tagged with FLAG and HA because of FLAG- and HA-tagged Dilp6HF allele from CRISPR/CAS9. In this ELISA assay, the plate wells were coated with anti-FLAG antibody, then FLAG(GS)HA or fruit fly hemolymph sample were added to the wells. FLAG(GS)HA and FLAG- and HA-tagged Dilp6 were quantified by anti-HA-Peroxidase 3F10 antibody and subsequent chromogenic reaction. For more details of the method, see the section “Hemolymph Dilp6 measurements by ELISA” in the link.

https://www.sciencedirect.com/science/article/pii/S2211124719309052

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Can I purchase custom FAM-labeled peptides for my research?

Yes. Specialized providers such as LifeTein offer custom synthesis of FAM-labeled peptides with high purity (>98%) and rigorous analytical validation. Their services include choices between 5-FAM and 6-FAM, optional spacers (Ahx, β-Ala), and a variety of conjugation positions (N-terminus, lysine side chain, cysteine-specific labeling).

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In Vivo Imaging and Biodistribution Studies

Cy7’s deep-tissue imaging capabilities have made it indispensable for tracking biodistribution, tumor targeting, and pharmacokinetics in living animals. Fluorescently labelled peptides and proteins administered to murine models can be non-invasively monitored over time, providing real-time insights into accumulation patterns at target sites. For example, Cy7-conjugated LPETGG peptides have been employed to visualize immune cell interactions in preclinical cancer models, leveraging the dye’s NIR emission to penetrate through tissues and reveal dynamic cellular processes.

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How to solubilize my synthetic peptides? #

Please refer to this FAQ for details: Handling and Storage of Synthetic Peptides. If the peptides are still cloudy, or turbid, you may have reached the limit of solubility. When the peptides are insoluble in the buffer, please try to sonicate, centrifuge, and lyophilize the peptide. Make sure to break the lyophilized lumps into a fine powder. Then try a small volume of a good agent 8M Urea, NMP, DMF, or DMSO to dissolve the peptide. Then dilute with water or your desired buffer. For peptides with Arg or LYs, you should try to lower the pH to 6 because the protonated amino acids will help solubility. Sonication and the following solvents may help with difficult peptides: 1) Begin with 100 % acetonitrile then dilute with water until 50% 2) Begin with 100% DMSO then dilute with water until 30 % 3) Dissolve it with 8M Urea 4) Dissolve it with 6 or 8 M Guanidine hydrochloride 5) 6M GuHCL, 0.05% TFA, pH2, 6) 100% TFA 7) 40% AcOH, 30%ACN, 30% water

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Enhancement of Metabolic Stability

The steric shield provided by the methyl group physically blocks access to proteolytic enzymes. By strategically methylating bonds identified as labile sites, one can dramatically increase the peptide’s longevity in biological systems, a crucial factor for any application requiring prolonged activity.

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