This product is the substituted counterpart of the BAX BH3 peptide (LT1045). Comparing the two supplied sequences, the leucine of the parent is replaced by alanine at the seventh position, and the stated molecular weights differ by approximately 43, consistent with that single substitution. Everything else in the sequence is unchanged. The residue involved is one of the conserved hydrophobic positions of the BH3 motif. Those residues insert into the hydrophobic groove of anti-apoptotic BCL-2 family proteins and supply much of the binding energy of the interaction, so replacing one with the much smaller alanine side chain is the standard way to construct a binding-deficient version of a BH3 peptide. Work on sequence and helicity requirements for BAX BH3 peptide activity examined substituted variants in exactly this manner, using them to establish which positions are required. The intended use is as a paired negative control rather than as an active reagent. Running it alongside LT1045 at matched concentration distinguishes an effect that genuinely depends on BH3-groove engagement from one caused by peptide concentration, charge, hydrophobicity or membrane perturbation, which is a real concern with amphipathic helical peptides at higher concentrations. Confirm the expected loss of binding in your own assay before relying on it as a control, since the degree of attenuation depends on the binding partner and format. | 