Omnic Software Free Download Ftir 16
the ftir experiments also gave us very interesting insight into the effects of stabilizer type on aggregation. the 1.5% sucrose formulation of anti-igf1r has a significant reduction in absorbance size (i.e. aggregation) at 37c and 72c. this formulation consists of only one stabilizer, l-cysteine, and is expected to be very aggregation prone. this is likely a result of the short length of the linker between anti-igf1r and l-cysteine. the ftir data suggest that the anti-igf1r gets linked to the sucrose through the hydroxyl groups of the sugar molecules, i. the anti-igf1r is directly bound to the sucrose and not the stabilizer. therefore, an attempt at destabilizing the linker using an appropriate amount of nacl in the formulation is likely to result in a loss of binding (as a result of the sucrose jumping to the bound stabilizer/anti-igf1r but the ftir absorbance size is not significantly impacted. this is in contrast to what is seen for the anti-igf1r with the 1.5% sucrose formulation where there is a large decrease in absorbance size at 37c and 72c. such a large decrease indicates that a large amount of hydroxyl groups in the sucrose is able to support a direct interaction with the anti-igf1r (resulting in a 'two-level' interaction - as in anti-igf1r is bound via sucrose molecules).
Omnic Software Free Download Ftir 16
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methanol is often used as a solvent to prepare antibody formulations but ethanol (etoh) is used less frequently due to the inherent risk of protein precipitation. since the amide i peak in the ftir spectra primarily corresponds to the c=o stretching vibration from the peptide bond, ftir measurements were taken to compare etoh- and methanol-based formulations for both anti-igf1r and anti-tslp. after heating the formulation to 72c, the amide i spectra at 1637cm1 (etoh-based) and 1628cm1 (methanol-based) show similar levels of unfolding (fig. 5). overall these data demonstrate that the formulation of both anti-igf1r and anti-tslp with either ethanol or methanol has little to no effect on the conformational changes occurring upon heating past the tms as long as the antibody is well-dispersed in the formulation. heating the formulation to 82c, the c=o peak at 1630cm1 is slightly higher (lower amount of unfolding) in the methanol-based formulation in both anti-igf1r and anti-tslp. as this peak represents the c=o group of a protein backbone, the data for anti-igf1r and anti-tslp is consistent with a slightly greater amount of aggregation at 82c in the methanol formulation compared to etoh. regardless, the formation of aggregates upon heating (at least to 82c) in the methanol formulation is still reversible as evidenced by the re-formation of the peak at 1637cm1. if ftir were the only technique used to study protein unfolding/aggregation, then it is unlikely that any of these data would have been obtained.