High Conformational Stability of Cytochrome P-450 1A2. Evidence from UV Absorption Spectra

1998 ◽  
Vol 63 (3) ◽  
pp. 441-448 ◽  
Author(s):  
Pavel Anzenbacher ◽  
Nicole Bec ◽  
Jiří Hudeček ◽  
Reinhard Lange ◽  
Eva Anzenbacherová
Keyword(s):  
Absorption Spectra ◽  
Conformational Changes ◽  
Conformational Stability ◽  
Specific Inhibitor ◽  
Maximum Amplitude ◽  
Side Chains ◽  
Spectral Maximum ◽  
Stable Conformation ◽  
Fourth Derivative ◽  
Cytochrome P 450

The fourth derivative of absorption spectra between 260 and 310 nm were used for monitoring the changes in exposure of tyrosine and tryptophan side chains in cytochrome P-450 1A2 to solvent. Titration of the enzyme with a specific inhibitor, α-naphthoflavone (2-phenylazo[h]chromen-4-one) to inhibitor concentration of 30 μM resulted in small but pronounced changes in derivative spectra (decrease in the maximum amplitude, downshift of the spectral maximum at about 293 nm) corresponding to the exposure of tryptophans towards the solvent. Further addition of the inhibitor led to a decrease of the exposure of these aromatic side-chains. Similar behaviour was also observed in this work for other cytochromes P-450 (2B4 and 11A1). The fourth derivative of absorption spectra was also used to examine the stability of the enzyme both in the presence and absence of α-naphthoflavone, with increasing pressure (up to 400 MPa) and temperature (up to 35 °C) as pertubing factors. The results show that cytochrome P-450 1A2 has a stable conformation as all the conformational changes observed were (spectrally) fully reversible.

Infrared spectra of N-acetyl-L-α-amino-acid N'-methylamides with aliphatic side chains in non-polar solvents

1981 ◽  
Vol 46 (3) ◽  
pp. 772-780 ◽  
Author(s):  
Jorga Smolíková ◽  
Jan Pospíšek ◽  
Karel Bláha
Keyword(s):  
Amino Acid ◽  
Conformational Changes ◽  
Infrared Spectra ◽  
Room Temperature ◽  
Side Chains ◽  
Polar Solvents

Infrared spectra of the L-alanine (I), L-leucine (II), L-valine (III) and L-tert-leucine (IV) N-acetyl N'-methylamides were measured. Amides I-IV are not self associated in tetrachlormethane in the concentration 2 . 10-5 mol l-1 at room temperature and in tetrachloroethylene in the concentration 1.5 . 10-4 mol l-1 at temperatures above 65° C. True conformational changes are observable only with the least flexible amide IV which exists at room temperature in a C5 conformation. This conformational type is also highly populated in the valine derivative III, but is less important in the alanine and leucine derivatives I and II in which the intramolecularly bonded C7 and the distorted hydrogen-nonbonded conformations contribute seriously.

Photoinduced conformational changes of azoaromatic polyaspartates containing octadecyl side chains

1990 ◽  
Vol 28 (5) ◽  
pp. 1161-1170 ◽  
Author(s):  
Akihiko Ueno ◽  
Kayo Adachi ◽  
Junko Nakamura ◽  
Tetsuo Osa
Keyword(s):  
Conformational Changes ◽  
Side Chains

Synthesis and optoelectronics properties of diblock copolymer of P3HT containing thiol-side chains and its hybrid nanocomposite

RSC Advances ◽  
2016 ◽  
Vol 6 (112) ◽  
pp. 110686-110694 ◽  
Author(s):  
Yisha Qiao ◽  
Yixuan Du ◽  
Yinfeng Liu ◽  
Yunbo Li
Keyword(s):  
Absorption Spectra ◽  
Diblock Copolymer ◽  
Side Chains ◽  
Hybrid Nanocomposite ◽  
Broad Absorption ◽  
Elliptical Shape ◽  
Weight Content ◽  
Hybrid Nanoparticle ◽  
Nanoparticle Film

DP-P3HT-SH in global, leaf-like and elliptical shape states exhibiting broad absorption spectra between 300 nm and 650 nm, and the conductivity values of a DP-P3HT-S-AuNPs hybrid nanoparticle film as a function of the weight content of AuNPs.

scholarly journals Real-time visualization of conformational changes within single MloK1 cyclic nucleotide-modulated channels

2016 ◽  
Vol 7 (1) ◽  
Author(s):  
Martina Rangl ◽  
Atsushi Miyagi ◽  
Julia Kowal ◽  
Henning Stahlberg ◽  
Crina M. Nimigean ◽  
...  
Keyword(s):  
Real Time ◽  
Conformational Changes ◽  
Cyclic Nucleotide ◽  
High Speed ◽  
Function Analysis ◽  
Stable Conformation ◽  
Mesorhizobium Loti ◽  
Force Microscopy ◽  
Atomic Force ◽  
Real Time Visualization

AbstractEukaryotic cyclic nucleotide-modulated (CNM) ion channels perform various physiological roles by opening in response to cyclic nucleotides binding to a specialized cyclic nucleotide-binding domain. Despite progress in structure-function analysis, the conformational rearrangements underlying the gating of these channels are still unknown. Here, we image ligand-induced conformational changes in single CNM channels from Mesorhizobium loti (MloK1) in real-time, using high-speed atomic force microscopy. In the presence of cAMP, most channels are in a stable conformation, but a few molecules dynamically switch back and forth (blink) between at least two conformations with different heights. Upon cAMP depletion, more channels start blinking, with blinking heights increasing over time, suggestive of slow, progressive loss of ligands from the tetramer. We propose that during gating, MloK1 transitions from a set of mobile conformations in the absence to a stable conformation in the presence of ligand and that these conformations are central for gating the pore.

The Mobility of Tryptophan and Dansyl Fluorophores in Labelled Poly(N-ethylacrylamide) and Poly(N-ethylmethacrylamide)

1993 ◽  
Vol 58 (10) ◽  
pp. 2383-2395 ◽  
Author(s):  
František Mikeš ◽  
Drahomír Výprachtický ◽  
Jan Pecka
Keyword(s):  
Conformational Changes ◽  
High Viscosity ◽  
Side Chains ◽  
Fluorescence Depolarization ◽  
Polymer Backbone ◽  
Short Side ◽  
Low Viscosity ◽  
Viscosity Range ◽  
Methylene Groups ◽  
Intramolecular Association

The mobility of tryptophan fluorophore in N-butyl-Nα-acetyltryptophanamide and in side chain of labelled poly(N-ethylacrylamide) and poly(N-ethylmethacrylamide) was investigated by the fluorescence depolarization method. The mobility of the fluorophore in the low-molecular-weight model is much higher than in side chains of the polymers. Different steric hindrance by the polymer backbone can explain the higher mobility of the fluorophore in poly(N-ethylacrylamide) and in poly(N-ethylmethacrylamide). The mobility of 5-dimethylamino-1-naphthalenesulfonamide (dansyl) fluorophore in side chains of labelled poly(N-ethylmethacrylamide) in the high-viscosity range increases with increasing number of methylene groups in side chains. The low-viscosity range, the rate s of conformational changes in short side chains (n = 2 - 7) are approximately constant and significantly decrease in long side chains (n = 10, 12). The drop in the rates is probably due to intramolecular association of the long hydrophobic chains in water.

Light-induced conformational changes in chiral polymers with photochromic side chains

1984 ◽  
Vol 56 (3) ◽  
pp. 329-342 ◽  
Author(s):  
F. Ciardelli ◽  
C. Carlini ◽  
R. Solaro ◽  
Angelina Altomare ◽  
O. Pieroni ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Side Chains ◽  
Chiral Polymers

Synthesis and Absorption Spectra of Poly(3-(phenylenevinyl)thiophene)s with Conjugated Side Chains

2006 ◽  
Vol 39 (2) ◽  
pp. 594-603 ◽  
Author(s):  
Jianhui Hou ◽  
Lijun Huo ◽  
Chang He ◽  
Chunhe Yang ◽  
Yongfang Li
Keyword(s):  
Absorption Spectra ◽  
Side Chains
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