Peptide Handling Guideline

Reconstitution Guideline

Proper peptide handling and solubilization is the starting point of a successful bioassay project, and we believe this handling guideline will help you dissolve your peptides properly. On CoA along with each peptide delivery, you may also see reconstitution conditions which we have used in the peptide purification process – this is for your reference only, you may dissolve your peptide in a different solvent according to your assay needs.

– Use only a small aliquot of peptide to test the dissolution method. Once satisfied, apply to the larger aliquot as needed.

– In principle, solvent used should be the solvent that will facilitate or be compatible with your experiment. However, we shall also keep in mind that there might be a challenge sometimes to find an “ideal” solvent which will solubilize peptides, maintain their integrity and be compatible with biological assays.

-For initial solvent used should be the most appropriate one. For example, for a very hydrophobic peptide, it is better to dissolve it in a small volume of organic solvent (such as DMSO or acetonitrile) before applying the aqueous solution. In other words, adding organic solvent to a suspension of hydrophobic peptide in aqueous solution is not likely to help much in dissolving.

– Peptide solution might be unstable at temperatures even lower than -20°C. As such, a Peptides Forum once prepared should be used as soon as possible.

What solvent(s) I can use to dissolve my peptides?

If it is a short peptide which is 5aa or less, try sterile distilled water first and it is likely to dissolve.

For other peptides, the overall charge of the peptide will help determine which initial solvent to use. Assign a value of -1 to acidic residues which include Asp(D), Glu(E), and the C-terminal free acid(-COOH). Assign a value of +1 to basic residues which include Arg (R), Lys (K), His (H), and the N-terminal free amine(-NH2). Calculate the overall charge of the entire peptide.

1. If the overall charge of the peptide is positive (a basic peptide), try to dissolve the peptide in sterile distilled water first. If water fails, add ~20% acetic acid solution. If the peptide still does not dissolve, add drops of TFA (< 50ul), or use 0.1%TFA/H2O to solubilize the peptide. Then dilute the peptide solution to the desired concentration.

2. If the overall charge of the peptide is negative (an acidic peptide), try to dissolve the peptide in sterile distilled water first. If the peptide persists as visible particles, sonication can be tried. If water fails, add NH4OH (<50ul) or 0.1%NH4OH drop-wise. Then dilute the peptide solution to the desired concentration. If the peptide contains Cys, do NOT use basic solutions (NH4OH), but use DMF instead.

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