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Reconstitution Guideline

Appropriate peptide handling and solubilization is definitely the starting point of a thriving bioassay project, and we think this handling guideline can help you dissolve your peptides properly. On CoA together with each and every peptide delivery, you could also see reconstitution circumstances which we've applied inside the peptide purification course of action - this really is for your reference only, you might dissolve your peptide in a distinctive solvent according to your assay demands.

- Use only a modest aliquot of peptide to test the dissolution technique. When happy, apply for the bigger aliquot as needed.

- In principle, solvent made use of really should be the solvent which will facilitate or be compatible along with your experiment. However, we shall also bear in mind that there could be a challenge from time to time to locate an "ideal" solvent which will solubilize peptides, sustain their integrity and be compatible with biological assays.

-For initial solvent utilized needs to be probably the most suitable one. For instance, to get a pretty hydrophobic peptide, it's much better to dissolve it in a smaller volume of organic solvent (for instance DMSO or acetonitrile) just before applying the aqueous option. In other words, adding organic solvent to a suspension of hydrophobic peptide in aqueous option will not be probably to assist a great deal in dissolving.

- Peptide remedy may be unstable at temperatures even reduce than -20°C. As such, a peptide resolution after prepared need to be applied as soon as you possibly can.

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

If it can be a short peptide which can be 5aa or much less, attempt sterile distilled water first and it is actually likely to dissolve.

For other peptides, the overall charge in the peptide will aid ascertain which initial solvent to utilize. Assign a worth of -1 to acidic residues which involve Asp(D), Glu(E), plus the C-terminal free of charge acid(-COOH). Assign a value of +1 to basic residues which incorporate Arg (R), Lys (K), His (H), plus the N-terminal free amine(-NH2). Calculate the general charge in the entire peptide.

1. In the event the overall charge on the peptide is optimistic (a basic peptide), attempt to dissolve the peptide in sterile distilled water 1st. If water fails, add ~20% acetic acid remedy. In the event the peptide nonetheless will 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.

3. Peptide whose overall charge is zero (the peptide is considered neutral). It usually dissolves in organic solvents, such as acetonitrile, methanol, or isopropanol. If this does not dissolve completely:

a) For peptides that tend to aggregate (due to the hydrophobic interaction), the addition of denaturants, such as 8M urea or 6M guanidine-HCl, may also be required.

b) For very hydrophobic peptides (containing more than 75% hydrophobic residues), add DMSO drop-wise (use DMF instead for Cys containing peptides), and then dilute the solution with water to the desired concentration.

Storage Guideline

Most lyophilized peptides shall be stable at room temperature for at least a few weeks. For long term storage, it is strongly recommended that you store peptide in powder form at -20°C or lower, away from strong light, and under dry condition. Repeated freeze-thaw cycles should be avoided.

The shelf life of peptide solutions is limited, especially for peptides containing cysteine(C), methionine(M), tryptophan(W), asparginine(N), glutamine(Q), or N-terminal glutamic acid(E). For example, a Cys-containing peptide is easily oxidised, especially in basic conditions; some residues are easy to racemise, such as Proline. Avoid DMSO if the peptide contains Met, Cys or Trp, due to sulfoxide or disulfide formation. Peptide stability becomes worse when in a solution, especially at the higher pH (pH>8). We therefore suggest maintaining options in the array of pH 4-6. It truly is advised that peptides containing methionine, cysteine, or tryptophan residues be stored in oxygen-free atmosphere to prevent oxidation. The presence of dithiothreitol (DTT) is often beneficial in stopping oxidation.

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