Time-resolved hole-burning study on myoglobin: fluctuation of restricted water within distal pocket. 2001

Y Shibata, and H Ishikawa, and S Takahashi, and I Morishima
Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Corporation, Hyogo 661-0974, Japan. yshibata@ile.osaka-u.ac.jp

We have studied the equilibrium fluctuation dynamics of Zn-substituted myoglobin and its His64-->Leu (H64L) mutant in the pH range from 5 to 9 by using time-resolved transient-hole-burning (TRTHB) spectroscopy. In the H64L mutant, we have observed a largely reduced width of the absorption spectrum and only a slight temporal shift of the hole-burning spectrum. These observations both reflect the suppressed conformational fluctuation in the mutant. On the other hand, the pH-dependent change in the absorption spectrum could not be solely explained by the change in the protonation state of His64 induced by the pH change. These results suggest that although the fluctuation dynamics observed by the TRTHB experiment of the native sample mainly reflects the conformational motion around His64, the interconversion process of His64 between its protonated and unprotonated states has a minor contribution. Instead, we have proposed a tentative interpretation that the motion of the water molecule around His64 is the main source of the observed dynamics in the TRTHB technique.

UI MeSH Term Description Entries
D007834 Lasers An optical source that emits photons in a coherent beam. Light Amplification by Stimulated Emission of Radiation (LASER) is brought about using devices that transform light of varying frequencies into a single intense, nearly nondivergent beam of monochromatic radiation. Lasers operate in the infrared, visible, ultraviolet, or X-ray regions of the spectrum. Masers,Continuous Wave Lasers,Pulsed Lasers,Q-Switched Lasers,Continuous Wave Laser,Laser,Laser, Continuous Wave,Laser, Pulsed,Laser, Q-Switched,Lasers, Continuous Wave,Lasers, Pulsed,Lasers, Q-Switched,Maser,Pulsed Laser,Q Switched Lasers,Q-Switched Laser
D009211 Myoglobin A conjugated protein which is the oxygen-transporting pigment of muscle. It is made up of one globin polypeptide chain and one heme group.
D011522 Protons Stable elementary particles having the smallest known positive charge, found in the nuclei of all elements. The proton mass is less than that of a neutron. A proton is the nucleus of the light hydrogen atom, i.e., the hydrogen ion. Hydrogen Ions,Hydrogen Ion,Ion, Hydrogen,Ions, Hydrogen,Proton
D006736 Horses Large, hoofed mammals of the family EQUIDAE. Horses are active day and night with most of the day spent seeking and consuming food. Feeding peaks occur in the early morning and late afternoon, and there are several daily periods of rest. Equus caballus,Equus przewalskii,Horse, Domestic,Domestic Horse,Domestic Horses,Horse,Horses, Domestic
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D006863 Hydrogen-Ion Concentration The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D001703 Biophysics The study of PHYSICAL PHENOMENA and PHYSICAL PROCESSES as applied to living things. Mechanobiology
D013053 Spectrophotometry The art or process of comparing photometrically the relative intensities of the light in different parts of the spectrum.
D013816 Thermodynamics A rigorously mathematical analysis of energy relationships (heat, work, temperature, and equilibrium). It describes systems whose states are determined by thermal parameters, such as temperature, in addition to mechanical and electromagnetic parameters. (From Hawley's Condensed Chemical Dictionary, 12th ed) Thermodynamic

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