Basis of Derivative Spectrophotometry

Saakov, V. S.; Drapkin, Valery Z.; Кривченко, А. И.; Розенгарт, Е. В.; Bogachev, Yuri V.; Knyazev, Mikhail N.

doi:10.1007/978-3-7091-1007-2_2

Cited by 4 publications

(2 citation statements)

References 126 publications

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“…The number of components and their frequency positions were determined by the negative minima in the second derivatives of the ATR spectra. This method allows us to enhance the separation of overlapping bands (27). All original protein spectra were baseline-corrected between 2800 and 1500 cm À1 for further analysis.…”

Section: Curve Fitting Of the Amide I Regionmentioning

confidence: 99%

Insights into the Aggregation Mechanism of PolyQ Proteins with Different Glutamine Repeat Lengths

Yushchenko

Deuerling

Hauser

2018

Biophysical Journal

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Polyglutamine (polyQ) diseases, including Huntington's disease, result from the aggregation of an abnormally expanded polyQ repeat in the affected protein. The length of the polyQ repeat is essential for the disease's onset; however, the molecular mechanism of polyQ aggregation is still poorly understood. Controlled conditions and initiation of the aggregation process are prerequisites for the detection of transient intermediate states. We present an attenuated total reflection Fourier-transform infrared spectroscopic approach combined with protein immobilization to study polyQ aggregation dependent on the polyQ length. PolyQ proteins were engineered mimicking the mammalian N-terminus fragment of the Huntingtin protein and containing a polyQ sequence with the number of glutamines below (Q11), close to (Q38), and above (Q56) the disease threshold. A monolayer of the polyQ construct was chemically immobilized on the internal reflection element of the attenuated total reflection cell, and the aggregation was initiated via enzymatic cleavage. Structural changes of the polyQ sequence were monitored by time-resolved infrared difference spectroscopy. We observed faster aggregation kinetics for the longer sequences, and furthermore, we could distinguish β-structured intermediates for the different constructs, allowing us to propose aggregation mechanisms dependent on the repeat length. Q11 forms a β-structured aggregate by intermolecular interaction of stretched monomers, whereas Q38 and Q56 undergo conformational changes to various β-structured intermediates, including intramolecular β-sheets.

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Section: Curve Fitting Of the Amide I Regionmentioning

confidence: 99%

Insights into the Aggregation Mechanism of PolyQ Proteins with Different Glutamine Repeat Lengths

Yushchenko

Deuerling

Hauser

2018

Biophysical Journal

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“…The experimentally obtained optical spectra are presented in Figures 2 and 3. Further, the optical spectra of the inducers were measured in a hexane solution at a concentration of 3  10 −5 M, which was suitable for performing the CD measurements [36]. The spectrophotometer was set to a 'low' sensitivity mode with low scanning speed and five time scans for integrated measurement by a J-720 CD spectrophotometer from JASCO.…”

Section: Methodsmentioning

confidence: 99%

Estimation of the helical twisting power of chiral inducers by time-dependent density functional theory (TD-DFT) for electrochemical polymerization in cholesteric liquid crystals

Shen

Goto

2018

Molecular Crystals and Liquid Crystals

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： Five chiral compounds were designed and synthesized using the Mitsunobu reaction to act as chiral inducers (i.e., chiral dopants) for the transformation of a nematic liquid crystal (LC) (4-n-octoxy-4ʹ-cyanobiphenyl) into a cholesteric LC. These chiral inducers contain two types of chiral alkyl chains with different kinds of achiral mesogenic cores (biphenylcarboxylate, biphenoxy, and cyanobiphenoxy. We observed that the achiral mesogenic cores affected the helical twisting power in terms of both induction strength and helicity (left-/right-hand introduction). All the ester type inducers exhibited a positive Cotton effect and right-hand helical twisting power (HTP). However, ethers exhibited a negative Cotton effect and left-hand HTP. The microscopic HTPs (β M) of these inducers demonstrate a linear relation with their optical activities (ellipticity near the absorption maximum). Further, the time-dependent density functional theory (TD-DFT) calculation using the B3LYP/6-311++G (d, p) method has been used to predict the circular dichroism spectra of these inducers. The predicted optical activity was observed to be in accordance with that observed in the experimental result. This study proposes a method for predicting the HTP of chiral inducers that can be applied to achieve polymerization in the reaction fields of cholesteric LCs.

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