Mössbauer spectroscopy on nonequilibrium states of myoglobin: a study of r-t relaxation

Prusakov, V. E.; Steyer, Jean‐Philippe; Parak, F.

doi:10.1016/s0006-3495(95)80435-2

Cited by 39 publications

(54 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Spectroscopic investigations have shown that Xe1 is the primary sink of CO at temperatures above the characteristic temperature where protein dynamics becomes important (29). Taking into account low-and high-temperature dynamics studies on Mb (3,5,52) and relating them to our time-resolved results at room temperature, we propose that two fundamental processes are responsible for CO migration in Mb. (i) Protein dynamics enables structural f luctuations and transiently opens and closes channels for the CO to migrate to positions where it is trapped effectively.…”

Section: Events Faster Than Our Experimental Time Resolution: Subnanomentioning

confidence: 66%

Ligand migration pathway and protein dynamics in myoglobin: A time-resolved crystallographic study on L29W MbCO

Schmidt

Nienhaus

Pahl

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

156

182

View full text Add to dashboard Cite

By using time-resolved x-ray crystallography at room temperature, structural relaxations and ligand migration were examined in myoglobin (Mb) mutant L29W from nanoseconds to seconds after photodissociation of carbon monoxide (CO) from the heme iron by nanosecond laser pulses. The data were analyzed in terms of transient kinetics by fitting trial functions to integrated difference electron density values obtained from select structural moieties, thus allowing a quantitative description of the processes involved. The observed relaxations are linked to other investigations on protein dynamics. At the earliest times, the heme has already completely relaxed into its domed deoxy structure, and there is no photodissociated CO visible at the primary docking site. Initial relaxations of larger globin moieties are completed within several hundred nanoseconds. They influence the concomitant migration of photodissociated CO to the Xe1 site, where it appears at Ϸ300 ns and leaves again at Ϸ1.5 ms. The extremely long residence time in Xe1 as compared with wild-type MbCO implies that, in the latter protein, the CO exits the protein from Xe1 predominantly via the distal pocket. A well-defined deligated state is populated between Ϸ2 s and Ϸ1 ms; its structure is very similar to the equilibrium deoxy structure. Between 1.5 and 20 ms, no CO is visible in the protein interior; it is either distributed among many sites within the protein or has escaped to the solvent. Finally, recombination at the heme iron occurs after >20 ms.kinetics ͉ Laue crystallography ͉ protein relaxation P roteins are not rigid molecules but fluctuating entities. They can adopt a large number of different conformations that can be depicted as local minima on a rugged energy surface (1). The dynamics of proteins shows strong analogies to the dynamics of viscous liquids. Motions occur on time scales from Ϸ10 Ϫ14 s to several thousands of seconds. Time and temperature are important determinants of protein motions on the energy landscape. At ambient temperature, a protein might be able to explore the entire landscape within a certain time interval, whereas it will become increasingly confined in a small region of its conformational space as the temperature is decreased (2, 3). Above a characteristic temperature T c (Ϸ180 K), quasidiffusive motions become important (4, 5). A significant fraction of conformational transitions occurs between 100 ps and a few nanoseconds in the case of myoglobin (Mb). Below T c , these fluctuations become more and more arrested. Proteins where larger motions are required for their function will cease to work.One method of studying protein dynamics is to generate a nonequilibrium state, for example, by changing the sample pressure, temperature, the concentrations of reaction components in fast mixing experiments, or by photodissociating ligands from proteins using short laser pulses. In a crystalline sample, the subsequent relaxation can be followed on the atomic scale by time-resolved x-ray crystallography (6-10) and interpreted kin...

show abstract

Section: Events Faster Than Our Experimental Time Resolution: Subnanomentioning

confidence: 66%

Ligand migration pathway and protein dynamics in myoglobin: A time-resolved crystallographic study on L29W MbCO

Schmidt

Nienhaus

Pahl

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

156

182

View full text Add to dashboard Cite

show abstract

“…DFT calculations have shown that the Fe-O distance will increase by 0.1 Å when the Fe IV -OH goes from being a donor to becoming an acceptor of a hydrogen bond to the distal His (48 Resting State -In the 1970s Gasyna (130) showed that ferric Mb can be one-electron reduced by radiolysis of 60 Co at 77 K. This is the same effect that we observed for our ferric Mb crystals and that Engler et al (131) observed after x-ray exposure. A reduction at low temperature 77-110 K probably reduces the Fe III to Fe II , but at this temperature the water that ligates to the iron will not be able to move away to generate the normal ferrous deoxy state (132,133). The intermediate state is most probably a low spin (S ϭ 0) ferrous Fe II -H 2 O or Fe II -OH state.…”

Section: Discussionmentioning

confidence: 99%

“…A very recent and thorough survey on cryoradiolytic reduction of crystalline heme proteins has demonstrated a very fast reduction of ferric Mb (134), which confirms our observations. In frozen solutions the low spin ferrous intermediates relax to the normal high spin ferrous deoxy Mb during heating (132,133). When we carried out a short annealing of this state in crystals it was the high spin ferric Mb state that was regenerated and not the ferrous deoxy state.…”

Section: Discussionmentioning

confidence: 99%

Crystallographic and Spectroscopic Studies of Peroxide-derived Myoglobin Compound II and Occurrence of Protonated FeIV–O

Hersleth

Uchida

Røhr

et al. 2007

Journal of Biological Chemistry

View full text Add to dashboard Cite

“…7. The experiments have been analyzed by a simple model where a distributed energy barrier had to be surmounted for structural relaxation [41].…”

Section: The Functional Relevance Of Slow Quasidiffusive Motionsmentioning

confidence: 99%

A Physical Picture of Protein Dynamics and Conformational Changes

et al. 2007

View full text Add to dashboard Cite

A physical model is reviewed which explains different aspects of protein dynamics consistently. At low temperatures, the molecules are frozen in conformational substates. Their average energy is 3/2RT. Solid-state vibrations occur on a time scale of femtoseconds to nanoseconds. Above a characteristic temperature, often called the dynamical transition temperature, slow modes of motions can be observed occurring on a time scale between about 140 and 1 ns. These motions are overdamped, quasidiffusive, and involve collective motions of segments of the size of an α-helix. Molecules performing these types of motion are in the "flexible state". This state is reached by thermal activation. It is shown that these motions are essential for conformational relaxation. Based on this picture, a new approach is proposed to understand conformational changes. It connects structural fluctuations and conformational transitions.

show abstract

Mössbauer spectroscopy on nonequilibrium states of myoglobin: a study of r-t relaxation

Cited by 39 publications

References 17 publications

Ligand migration pathway and protein dynamics in myoglobin: A time-resolved crystallographic study on L29W MbCO

Ligand migration pathway and protein dynamics in myoglobin: A time-resolved crystallographic study on L29W MbCO

Crystallographic and Spectroscopic Studies of Peroxide-derived Myoglobin Compound II and Occurrence of Protonated FeIV–O

A Physical Picture of Protein Dynamics and Conformational Changes

Contact Info

Product

Resources

About