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Purity, Quality and Design

Page Contents
Help with choosing a custom peptide
Delivering quality
 
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Mimotopes’ peptides are made using the latest technology and advanced solid phase techniques. Standard peptide lengths range from 2 to 35 residues, in quantities from 1mg to greater than 100mg. We will purify the peptides to your requirements, or you may choose from the standard range; unpurified, 70%, 80%, 90% and 95%.

 

Help with choosing a custom peptide

Users of custom peptides often know exactly which peptide they need in order to carry out their experiments, but may not know what quantity of the peptide or purity level they should order. Unpurified peptides can be very pure or very impure, depending on the individual peptide sequence. In most cases, it is therefore best to order peptides at a defined purity level rather than unpurified. Naturally, purification adds a lot to the cost of the peptide. Commercial peptide synthesis and purification can be carried out economically at scales as small as 1mg as the target quantity of peptide, however this is sufficient peptide for many small scale or one-off experiments. Conversely, the cost does not increase in direct proportion to the amount, so larger scales of manufacture are better "value for money".

Typical amount/purity combinations would be:

  • To test the bioactivity of a peptide to establish if further work is worthwhile: 1mg at a purity of >70%;
  • To raise an antipeptide serum: 5mg at a purity of >70%;
  • To test bioactivity in an animal or to perform NMR analysis: 10mg at a purity of >95%.
Peptide purity definition

Purity is conventionally established using the criterion "% of total area under the curve" for the main peptide peak in an analytical chromatogram. It is vital that a second technique, such as mass spectrometry, be used to verify that the main peak being quantitated is indeed the correct peptide.

Quality assurance is just as important, if not more important, for a custom-manufactured item than for an off-the shelf item. When you order a peptide it is vital that you receive a peptide with the correct sequence. A cheap peptide with the wrong sequence is no bargain. Part of the quality assurance of our custom peptide products arises from the use of computer-guided synthesis systems so that once a sequence is entered into our production database, the "human error" factor which can result in an incorrect sequence is overcome. You can even supply the sequence to us electronically by email, or using direct entry in this website, or using software you can download from this website, so that again no interpretation (i.e. retyping of sequences) is required to place the correct sequence(s) into our production database. Where we have any doubt at all as to the intended sequence, we will always confirm the sequence with you in writing before commencing work on your peptide.

If you need more information before you can make decisions about the format, quantity or purity of peptide you need, you can read the Peptide Technical section, go to the Delivering Quality section, or contact us with a specific inquiry.

 

Manufacturing custom peptides on robotic synthesiser
Biotinylated PepSets - Addition of a biotin group to a peptide is a convenient way to detect or immobilize the peptides in libraries

Delivering Quality

Here, we assume that you know the peptide sequence, quantity and purity specifications you require. If not, please go to Help with Choosing a Custom Peptide or download the Custom Peptides Brochure. Below, we introduce our approach to quality, supply and warranty issues.

The quality assurance of our custom peptide products starts with the use of an integrated computer-guided synthesis and manufacturing system, so that once a sequence is entered into our production database, the "human error" factor which could otherwise result in an incorrect sequence is eliminated. To help ensure that we make your peptide exactly as requested, you can supply the sequence electronically in single letter code using your usual email provider, or using direct entry in this website, or using software you can download from this website, so that we can import the sequence(s) into our production database without. retyping. Where we have any doubt at all as to the intended sequence, we will always confirm the sequence with you in writing before commencing work on your peptide.

Quality is also assured because our custom peptides, of all requested purity levels, are analyzed by electrospray mass spectrometry. Backing up tightly controlled manufacturing practices, this is our safeguard to ensure the correct peptides are shipped.

Manufacturing custom peptides on robotic synthesiser
Peptide derivitized with FMOC (fluorenylmethoxy-carbonyl) protecting group

We use the Fmoc solid phase synthesis strategy to make peptides ranging from very small scale (1mg) to medium (gram) scale. Purified peptides are passed down a preparative HPLC column and fractions are analyzed for purity and identity before pooling the best fractions to make the final product. For all the defined purity levels (i.e. >70% or higher), purity is quantitated by RP-HPLC (included in the quoted price). Other methods of analysis are available, such as amino acid analysis or sequencing (at additional cost).

If you order a peptide at >70% purity, the peptide may simply meet the minimum agreed purity level; however, if the peptide proves to be highly amenable to synthesis and purification, it is possible you will receive peptide with a purity of >95% or even higher. In such cases you will still only be billed for the originally quoted price.

We offer a range of peptide modifications such as unnatural amino acids, biotinylation, phosphorylation, cyclization, fluorescent labeling, and conjugation of peptide to proteins or affinity media (gels).

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