FTIR studies of recombinant human granulocyte-macrophage colony-stimulating factor in aqueous solutions: secondary structure, disulfide reduction and thermal behavior

FTIR Study of the Thermal Denaturation of α-Actinin in Its Lipid-Free and Dioleoylphosphatidylglycerol-Bound States and the Central and N-Terminal Domains of α-Actinin in D2O

“…In our study, the intermolecular hydrogen-bonded extended structure in proteins, which gives rise to the bands around 1686 or/and 1617 cm -1 in the FTIR spectra, was used as a sign of the protein denaturation. The feasibility of this method is based on the results of many earlier thermal denaturation studies of proteins with FTIR (26)(27)(28)34) and is reinforced by our observation that, in the spectra of the central domain of R-actinin, a band at 1615 cm -1 appeared at 60 °C (Figure 4) which is exactly the denaturation temperature of the central domain of R-actinin (39). Thus, we concluded that the denaturation of R-actinin in D 2 O and R-actinin in the presence of DOPG vesicles took place at 45 °C (Figure 1) and 60 °C (Figure 2), respectively.…”

“…H-D exchange has long been recognized as a powerful method for the study of protein conformational dynamics. The rate and extent of H-D exchange in proteins may be obtained with FTIR by measuring the decrease in intensity of the amide II band of the protein (28,33,49,51). Much information on the structure, dynamics, and water accessibility of proteins in the native state and in association with lipid membranes came from the measurements of the H-D exchange kinetics with FTIR (35,49,(51)(52)(53)(54).…”

“…But there is an onset of an intermolecular hydrogen-bonded extended structure at 45 °C since a band at 1686 cm -1 was apparent at this temperature. This band is the result of the protein denaturation (26)(27)(28). A sudden increase in the intensity at 1641 cm -1 occurs at 50 °C, which can be interpreted in terms of an increase of the random coil structure.…”

“…The denaturation of DOPG-bound R-actinin occurs at 60 °C. This is characterized as the appearance of the bands at 1618 and 1682 cm -1 which indicates the formation of intermolecular hydrogen-bonded extended structure (26)(27)(28)34). Upon heating from 50 to 55 °C, there is a shift of the peak from 1649 cm -1 to around 1645 cm -1 .…”

Characteristics of hydrogen bond formation between sugar and polymer in freeze‐dried mixtures under different rehumidification conditions and its impact on the glass transition temperature

“…Hence, the vibration state of the IR absorption band due to CO stretching was analyzed, to estimate the degree of formation of trehalose–PVP hydrogen bonds as follows: The band due to CO at around 1700–1600 cm −1 in the spectra was deconvolved using the OMNIC version 4.1a software (Nicolet). The factor, K , which is related to the extent of resolution of the overlapping component bands, and the halfwidth of the unresolved bands were set 2.0 and 30 cm −1 , respectively, which were optimal to maintain a flat baseline on both sides of the CO band and to show as many band components as likely 13. The overlapping bands in the deconvolved band were resolved using the PeakFit software program (SeaSolve Software, Inc., Framingham, MA).…”