Big LEN, human peptide

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

Batch to batch variation of the purity

Big LEN is a peptide derived from the C-terminal region of the proprotein convertase subtilisin/kexin type 1 inhibitor, commonly known as proSAAS or PCSK1N. This peptide corresponds to the sequence LETPAPQVPARRLLPP, though the N-terminal leucine is frequently absent in mass spectrometry analyses of cerebrospinal fluid, resulting in the commonly detected fragment ETPAPQVPARRLLPP. ProSAAS is a neuronally and endocrinely expressed protein that functions as a chaperone, inhibiting the aggregation of amyloidogenic peptides.

In the context of Alzheimer's disease, cerebrospinal fluid levels of proSAAS and its derived Big LEN peptide are consistently decreased. This reduction is observed across multiple independent proteomic studies and is supported by statistical significance. The consistent downregulation of this specific peptide fragment suggests it may reflect altered neuronal processing or retention of the parent protein within pathological brain aggregates, rather than being an artifact of sample preparation.

• Pedrero-Prieto CM, García-Carpintero S, Frontiñán-Rubio J, Llanos-González E, Aguilera García C, Alcaín FJ, Lindberg I, Durán-Prado M, Peinado JR, Rabanal-Ruiz Y. A comprehensive systematic review of CSF proteins and peptides that define Alzheimer's disease. Clin Proteomics. 2020 Jun 5;17:21. doi: 10.1186/s12014-020-09276-9. PMID: 32518535; PMCID: PMC7273668.
• Muqaku B, Oeckl P. Peptidomic Approaches and Observations in Neurodegenerative Diseases. Int J Mol Sci. 2022 Jun 30;23(13):7332. doi: 10.3390/ijms23137332. PMID: 35806335; PMCID: PMC9266836.

Trifluoroacetic acid (TFA) is a common counterion from the purification process using High-Performance Liquid Chromatography (HPLC). The presence of TFA can affect the peptide's net weight, appearance, and solubility.

Impact on Net Weight: The TFA salt contributes to the total mass of the product. In most cases, the peptide content constitutes >80% of the total weight, with TFA accounting for the remainder.

Solubility: TFA salts generally enhance the solubility of peptides in aqueous solutions.

In Biological Assays: For most standard in vitro assays, the residual TFA levels do not cause interference. However, for highly sensitive cellular or biochemical studies, please be aware of its presence.