scispace - formally typeset



About: Myoglobin is a(n) research topic. Over the lifetime, 4377 publication(s) have been published within this topic receiving 151708 citation(s). The topic is also known as: uniprot:P02144 & MB.

More filters
01 Jan 1971

2,117 citations

Journal ArticleDOI
08 Mar 1958-Nature
Abstract: To understand how a protein performs its individual biological function, it is essential to know its three-dimensional structure As early as 1934, JD Bernal and Dorothy Hodgkin (then Dorothy Crowfoot) showed [Bernal, J D & Crowfoot, D Nature 133, 794–795 (1934)] that proteins, when crystallized, would diffract X-rays to produce a complex pattern of spots They knew that these patterns contained all the information needed to determine a protein–s structure but, frustratingly, that information could not be deciphered By comparing patterns from crystals containing different heavy-metal atoms, Max Perutz and colleagues devised the approach that was to solve this riddle In 1958, J C Kendrew et al applied Perutz–s technique to produce the first three-dimensional images of any protein - myoglobin, the protein used by muscles to store oxygen

1,455 citations

Journal ArticleDOI
TL;DR: The nonexponential rebinding observed at low temperatures and in solid samples implies that the innermost barrier has a spectrum of activation energies, similar to how myoglobin achieves specificity and order.
Abstract: Myoglobin rebinding of carbon monoxide and dioxygen after photodissociation has been observed in the temperature range between 40 and 350 K. A system was constructed that records the change in optical absorption at 436 nm smoothly and without break between 2 musec and 1 ksec. Four different rebinding processes have been found. Between 40 and 160 K, a single process is observed. It is not exponential in time, but approximately given by N(t) = (1 + t/to)-n, where to and n are temperature-dependent, ligand-concentration independent, parameters. At about 170 K, a second and at 200 K, a third concentration-independent process emerge. At 210 K, a concentration-dependent process sets in. If myoglobin is embedded in a solid, only the first three can be seen, and they are all nonexponential. In a liquid glycerol-water solvent, rebinding is exponential. To interpret the data, a model is proposed in which the ligand molecule, on its way from the solvent to the binding site at the ferrous heme iron, encounters four barriers in succession. The barriers are tentatively identified with known features of myoglobin. By computer-solving the differential equation for the motion of a ligand molecule over four barriers, the rates for all important steps are obtained. The temperature dependences of the rates yield enthalpy, entropy, and free-energy changes at all barriers. The free-energy barriers at 310 K indicate how myoglobin achieves specificity and order. For carbon monoxide, the heights of these barriers increase toward the inside; carbon monoxide consequently is partially rejected at each of the four barriers. Dioxygen, in contrast, sees barriers of about equal height and moves smoothly toward the binding site. The entropy increases over the first two barriers, indicating a rupturing of bonds or displacement of residues, and then smoothly decreases, reaching a minimum at the binding site. The magnitude of the decrease over the innermost barrier implies participation of heme and/or protein. The nonexponential rebinding observed at low temperatures and in solid samples implies that the innermost barrier has a spectrum of activation energies. The shape of the spectrum has been determined; its existence can be explained by assuming the presence of many conformational states for myoglobin. In a liquid at temperatures above about 230 K, relaxation among conformational states occurs and rebinding becomes exponential.

1,414 citations

Journal ArticleDOI
Abstract: 1-Anilino-8-naphthalene sulfonate binds stoichiometrically to a specific site on apomyoglobin and apohemoglobin. One mole of ANS† is bound per mole of apoprotein with a dissociation constant of the order of 10−5 M . Myoglobin and hemoglobin do not bind ANS. The addition of hemin displaces it from its complex with apomyoglobin, suggesting that ANS and heme bind at the same site. Its fluorescence changes markedly when it is bound to the apoprotein. The quantum yield is two-hundredfold higher than in water, while the emission peak is shifted from green to blue by 60 mμ. These changes are attributed to the essentially non-polar environment of the bound ANS. A similar dependence of quantum yield and emission maximum on the polarity of the environment is observed for solutions of ANS in various organic solvents. Fluorescence polarization and optical rotatory dispersion results indicate that the compactness and high helix content of myoglobin are retained in large part in the apomyoglobin-ANS complex. Highly efficient energy transfer is observed from the aromatic amino acids of the protein to the bound ANS. The use of anilinonaphthalene sulfonates as fluorescent probes of non-polar regions in proteins is discussed.

1,394 citations

Journal ArticleDOI
23 Feb 1989-Nature
TL;DR: The dynamical behaviour of myoglobin (and other globular proteins) suggests a coupling of fast local motions to slower collective motions, which is a characteristic feature of other dense glass-forming systems.
Abstract: Structural fluctuations in proteins on the picosecond timescale have been studied in considerable detail by theoretical methods such as molecular dynamics simulation1,2, but there exist very few experimental data with which to test the conclusions. We have used the technique of inelastic neutron scattering to investigate atomic motion in hydrated myoglobin over the temperature range 4–350 K and on the molecular dynamics timescale 0.1–100 ps. At temperatures below 180 K myglobin behaves as a harmonic solid, with essentially only vibrational motion. Above 180 K there is a striking dynamic transition arising from the excitation of non-vibrational motion, which we interpret as corresponding to tor-sional jumps between states of different energy, with a mean energy asymmetry of KJ mol −1. This extra mobility is reflected in a strong temperature dependence of the mean-square atomic displacements, a phenomenon previously observed specifically for the heme iron by Mossbauer spectroscopy3–5, but on a much slower timescale (10−7 s). It also correlates with a glass-like transition in the hydration shell of myoglobin6 and with the temperature-dependence of ligand-binding rates at the heme iron, as monitored by flash photolysis7. In contrast, the crystal structure of myoglobin determined down to 80 K shows no significant structural transition8–10. The dynamical behaviour we find for myoglobin (and other globular proteins) suggests a coupling of fast local motions to slower collective motions, which is a characteristic feature of other dense glass-forming systems.

973 citations

Network Information
Related Topics (5)
Amino acid

124.9K papers, 4M citations

85% related
Skeletal muscle

58.8K papers, 2.4M citations

80% related
Protein structure

42.3K papers, 3M citations

80% related
Binding site

48.1K papers, 2.5M citations

80% related

107.1K papers, 4.7M citations

80% related
No. of papers in the topic in previous years