Crude peptides are not recommended for biological assays. Crude peptides may contain large amounts of non-peptide impurities such as residual solvents, scavengers from cleavage, TFA, and other truncated peptides. TFA cannot be removed. Peptides are usually delivered as TFA salt. If residual TFA is a problem for your experiment, we recommend other salt forms such as acetate and hydrochloride. These salt forms are usually 20-30% more expensive than regular TFA salt. This is due to the peptide loss that takes place during the salt conversion and the greater amounts of raw materials required.
LifeTein® recommends the following levels of peptide purity for various projects:
>75% purity
- Peptide arrays
- Antigens for antibody production
- Competitive elution chromatography
- ELISA standards for measuring antisera titers
>80% purity
- Western blotting studies (non-quantitative)
- Enzyme-substrate studies (non-quantitative)
- Peptide blocking studies (non-quantitative)
- Affinity purification
- Phosphorylation assays
- Protein electrophoresis applications and immunocytochemistry
>95% purity
- ELISA standards and RIA protocols (quantitative)
- Receptor-ligand interaction studies (quantitative)
- In vitro bioassays and in vivo studies
- Enzyme studies and blocking assays (quantitative)
- NMR studies
- Mass spectrometry
- Other quantitative assays
>98% purity
- SAR Studies
- Clinical trials
- APIs (Active Pharmaceutical Ingredients)
- Commercial products
- X-ray crystallography studies
- Other sensitive experiments: enzyme-substrate studies, receptor-ligand interaction studies, blocking and competition assays
