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FAQ

What does it mean "TFA and salt free" ?

There are 2 issues:
- Excess TFA present from HPLC purification solvent with acetonitrile (AcCN) and both are (normally) removed by a thorough freeze/dry - lyophilisation step. At least we do it. And tfa is still present and content will be less then 10-15% for regular/average (not too charged, not too aromatic, not too many polar aa)

-TFA present as as counter anion: it is present by electrostatic-ion-ion and short distance ion to molecule interactions. There, total (guaranteed <1%) removal = exchange to acetate or Cl- is an additional step and requires extra charge.

All the % above depends upon the sequence. For example : peptide (arg)8 acetat salt is very difficult to make, because so much tfa is “sticking” to the peptide and has to be removed by several ion exchange steps.

eMail: Laurent_Fourmi@genosphere-biotech.de

.. some more questions & answers

How long will it take to get my peptide? Dispatch time will vary with length, scale, purity, and modifications ordered. Our average turn around time for 15-20 aa peptides, 25 mg with purities>95% is approximately 2-3 weeks.

Can I have special vialing for my peptides? Yes, we may vial your peptides under any particular conditions. Please contact us with your requirements and we will quote a very competitive price.

Can you synthesize cyclic peptides? Yes, we routinely synthesize peptides with cys-cys disulfide bridge cycles or head to tail lactam cycles.

Can you synthesize peptides in 96-wells format for screening purposes? We routinely prepare custom peptide libraries in 96-wells micro plate formats, fully MS characterized. Please contact us with your project details and we will quote a very competitive price.

There are some fluorescent peptide substrates, which I can find in catalogues, for a very cheap price, what is wrong with them ?
Yes, many fluorescent peptide substrates are mass-produced. However many peptides loose activity fast through degradation. The kinetics of oxidation and hydrolysis reactions varies from one sequence to another. Fresh synthesis is always better for these “biological active substrate" molecules.


What analytical data will you supply with my peptides? Every peptide undergoes stringent quality control procedures including analytical HPLC and mass spectrometry which accompanied all peptides.

How should I store my peptide? While lyophilized at 4°C is acceptable for short term storage, we recommend as optimum long term storage: Lyophilized at -20°C.

Schutzgruppen in der Peptidsynthese

  • Orthogonale Schutzgruppen

    Orthogonale Schutzgruppen Kombination bei der Merrifield *) Peptidsynthese an der festen Phase (z.B. Wang-Harz, Rink-Linker, SPSS).
    Die Fmoc Schutzgruppe (Fluorenylmethoxycarbonyl) für Aminogruppen kann unter schwach basischen Bedingungen wieder entfernt werden, ist jedoch unter sauren Bedingungen stabil. Daher kann sie gut in Verbindung mit der Boc-Schutzgruppe (tert-Butyloxycarbonyl) und der gebräuchlichen Schutzgruppe für Carbonsäuren, dem tert-Butylester, eingesetzt werden. Fmoc ist komplementär dazu, weil die Boc- und auch die tert-Butylester-Gruppe sauer mit Trifluoressigsäure (TFA) entfernt wird. Man spricht auch von einer orthogonalen Schutzgruppen Kombination. Beim Entschützen von Fmoc wird initial das saure Wasserstoff-Atom mit Hilfe einer Base, meist einem sekundären Amin,wie z.B. Piperidin in DMF, entfernt.

    *) Bruce Merrifield und Arnold Marglin haben diese Methode 1966 erstmals bei der Synthese von Insulin eingesetzt.

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