Yannick Guinet

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Pressure denaturation of lysozyme dissolved in H(2)O and D(2)O was analyzed using Raman investigations in a wide frequency range. The simultaneous analysis of regions corresponding to the molecular fingerprint of the protein (500-1800 cm(-1)), and the low- (50-450 cm(-1)) and high- (2600-3800 cm(-1)) frequency spectra, allow us to probe protein denaturation(More)
Thermal denaturation of bovine serum albumin (BSA) is analyzed from differential scanning calorimetry (DSC) and Raman spectroscopy investigations. DSC curves exhibit a marked dependence on protein concentration. BSA thermal denaturation becomes broader and bimodal, and the temperature of denaturation increases with increasing protein concentration. Raman(More)
We show in this paper the contribution of the whole Raman spectrum including the phonon spectrum, to detect, identify and characterize polymorphic forms of molecular compounds, and study their stability and transformation. Obtaining these kinds of information is important in the area of pharmaceutical compounds. Two different polymorphic systems are(More)
Raman investigations are carried out both in crystalline forms of caffeine and during the isothermal transformation of the orientationally disordered form I into the stable form II at 363 K. The time dependence of the Raman spectrum exhibits no significant change in the intramolecular regime (above 100 cm(-1)), resembling the spectrum of the liquid state.(More)
The influence of three well-known disaccharides, namely, trehalose, maltose, and sucrose, on some structural and dynamical properties of lysozyme has been investigated by means of molecular dynamics computer simulations in the 37-60 wt % concentration range. The effects of sugars on the protein conformation are found to be relatively weak, in agreement with(More)
Low-frequency Raman investigations were carried out upon pressurizing and grinding both crystalline forms of anhydrous caffeine at room temperature. These investigations have led to the detection of metastable states under stress. Upon moderated hydrostatic compression, only form I transform into a metastable state characterized by a Raman band-shape(More)
The phase transition of a model API, caffeine Form I, was studied during tableting process monitored with an instrumented press. The formulation used had a plastic flow behavior according to the Heckel model in the compression pressure range of 70-170 MPa. The quantitative methods of analysis used were Differential Scanning Calorimetry (DSC) and low(More)
This paper gives a detailed analysis of the low-frequency Raman spectrum (LFRS) in the 5-250cm(-1) region, corresponding to collective vibrations, in the crystalline forms and in the amorphous state of indomethacin (IMC). This study points out the high sensitivity of the LFRS to detect, identify and evaluate the first traces of crystallization in comparison(More)
Raman investigations were performed in situ during freeze-drying of two model proteins, lysozyme and chymotrypsinogen. The structures of proteins dissolved in 0-30 wt % solutions of trehalose in D2 O were monitored with the fingerprint (800-1800 cm(-1) ) spectrum, simultaneously with freezing, ice sublimation, and water desorption analyzed in the O-D(More)
Raman investigations were carried out in situ in real time during the lyophilization of three proteins (β-lactoglobulin, bovine serum albumin, and chymotrypsinogen) characterized by different structural properties. Structural changes in the proteins were only and systematically detected after the primary drying step of the lyophilization, through a(More)