Peptide Common Sense
Peptide generally needs to be stored from light, especially, at -20 degrees below for the long-term preservation, for the short term
storage, it can be saved at 4 ℃. The room temperature is available for short transportation .The Peptide is stable at -20 ℃, especially
when stored in adesiccator after freezedried. Before being exposed to the air, the lyophilized polypeptide may be kept at room temperature, which will reduce the humidity. When it is unable to be freezed drying, small sample volume storage is the best way.As
for those peptide that contains Cys, Met or Trp, the dissolved oxygen buffer is necessary, for such peptide is easy to oxidate with air.
Before the closure of bottles, we need some nitrogen or argon gas, because they will reduce oxidation. While, the peptide which contains Gln or Asn is relatively getting degradable easily, and they have shorter storage period compared with the simple peptide without those
problems.
Peptide dissolved
Dissolving peptide is very complex, it's hard to find out a suitable solvent. Usually, it needs to take a small test to determine a suitable
solvent, do not completely dissolve the peptide before determining the suitable solvent. The following methods will help you choose the
right solvent:
(1) determine the specific electric charge of the polypeptide, set acidic amino acids Asp (D), Glu (E) -1 and C-terminal COOH; basic
amino acids Lys (K), Arg (R), His (H) and the N-terminal NH2 is +1,and 0 electric charge of other amino acids, then calculate a number
of charges.
(2) if the net electric charge number> 0, the polypeptide is alkaline, can be dissolved in water, if insoluble or can not dissolved
completely,need to add acetic acid (over 10%); if the peptide still can not be dissolved, then need to add a small amount of TFA (25ul),
additionally,should add 500ul diluted water.
(3) if the net electric charge number <0, the polypeptide is acidic, should dissolved in water; if not soluble or not soluble completely,
should add aqueous ammonia (25ul), then add 500ul water dilution.
(4) if the net electric charge number = 0, the polypeptide is neutral, generally need to use an organic solvent such as acetonitrile ,
methanol,or isopropyl alcohol, DMSO, etc. It was also suggested that need to dissolve hydrophobic polypeptides with urea.
Peptide Synthesis Services:
1) Ordinary linear peptide: Chain length over 100 amino acid residues, milligram to gram scale.
2) Simple modified peptides: free N-terminal acetylation, and terminal amidation
3) Complex modified peptide: lipopeptide, phosphopeptide (Ser, Thr, Tyr), cyclic peptide (lactam ring,
disulfide ring), a fluorescent labeled peptide (FAM, FITC), biotin-labeled peptides, peptide compound
(MAP ), etc.
4) Protein Crosslinking: KLH, BSA, OVA.
5) We could supply peptide containing special amino acid: Contains D-amino acids and a variety
of amino acid derivatives.
6) Purity range: Crude peptide, Desalination,> 70%,> 80%,> 85%,> 90%,> 95%,> 98%,> 99%.
If any needs or questions regarding the peptide, please feel free to contact us via:
outside@dgpeptides.com,we will get back to you as soon as we receive your inquiry.
|