ALFA-tag peptide

ALFA-tag peptide

• COA/MS/HPLC Report
• Handling and Storage of Synthetic Peptides
• Material Safety Data Sheets (MSDS)

Batch to batch variation of the purity

H-SRLEEELRRRLTE-OH

H-Ser-Arg-Leu-Glu-Glu-Glu-Leu-Arg-Arg-Arg-Leu-Thr-Glu-OH

13

99.19%

C₆₉H₁₂₃N₂₅O₂₄

1686.86

Synthetic

Powder

The sequence of the minimal ALFA-tag (SRLEEELRRRLTE) is inspired by an artificial peptide (SRLEEELRRRL) reported to form a stable α-helix in solution24. It was selected based on the following criteria: (i) It features a high alpha-helical content, (ii) The sequence is absent in common eukaryotic model systems, (iii) It is hydrophilic and neutral at physiological pH while retaining moderate hydrophobic surfaces and (iv) It does not contain any primary amines that are modified by aldehyde-containing fixatives. The additional Thr-Glu (TE) dipeptide was added to the original peptide to neutralize its positive net charge and thus fully comply with the selection criteria defined above. To minimize any potential influence of neighboring secondary structures, the minimal ALFA-tag sequence was in addition framed by prolines.

Normally, this peptide will be delivered in lyophilized form and should be stored in a freezer at or below -20 °C. For more details, please refer to the manual: Handling and Storage of Synthetic Peptides

• Götzke, H., Kilisch, M., Martínez-Carranza, M. et al. The ALFA-tag is a highly versatile tool for nanobody-based bioscience applications. Nat Commun 10, 4403 (2019).

Trifluoroacetic acid (TFA) has a significant impact on peptides due to its role in the peptide synthesis process.

TFA is essential for the protonation of peptides that lack basic amino acids such as Arginine (Arg), Histidine (His), and Lysine (Lys), or ones that have blocked N-termini. As a result, peptides often contain TFA salts in the final product.

TFA residues, when present in custom peptides, can cause unpredictable fluctuations in experimental data. At a nanomolar (nM) level, TFA can influence cell experiments, hindering cell growth at low concentrations (as low as 10 nM) and promoting it at higher doses (0.5–7.0 mM). It can also serve as an allosteric regulator on the GlyR of glycine receptors, thereby increasing receptor activity at lower glycine concentrations.

In an in vivo setting, TFA can trifluoroacetylate amino groups in proteins and phospholipids, inducing potentially unwanted antibody responses. Moreover, TFA can impact structure studies as it affects spectrum absorption.