Trapp M

References (5)

Title : Pressure-induced molten globule state of human acetylcholinesterase: structural and dynamical changes monitored by neutron scattering - Marion_2015_Phys.Chem.Chem.Phys_17_3157
Author(s) : Marion J , Trovaslet M , Martinez N , Masson P , Schweins R , Nachon F , Trapp M , Peters J
Ref : Phys Chem Chem Phys , 17 :3157 , 2015
Abstract : We used small-angle neutron scattering (SANS) to study the effects of high hydrostatic pressure on the structure of human acetylcholinesterase (hAChE). At atmospheric pressure, our SANS results obtained on D11 at ILL (Grenoble, France) give a radius of gyration close to that calculated for a mixture of monomers, dimers and tetramers of the enzyme, suggesting a good agreement between hAChE crystal structure and its conformation in solution. Applying high pressure to the sample we found a global compression of about 11% of the enzyme up to a pressure of 900 bar and then again an extension up to 2.1 kbar indicating unfolding of the tertiary structure due to a molten globule (MG) state. On the other hand, we studied the influence of pressure up to 6 kbar on the dynamics of this enzyme, on the backscattering spectrometer IN13 at ILL. For the first time, we used elastic incoherent neutron scattering (EINS) to probe the differences between hAChE in its folded state (N), its high-pressure induced MG state and its unfolded state (U). Especially around the MG state at 1750 bar we found a significant increase in the dynamics, indicating a partial unfolding. A four-step-model is suggested to describe the changes in the protein.
ESTHER : Marion_2015_Phys.Chem.Chem.Phys_17_3157
PubMedSearch : Marion_2015_Phys.Chem.Chem.Phys_17_3157
PubMedID: 25515378

Title : Correlation of the dynamics of native human acetylcholinesterase and its inhibited huperzine A counterpart from sub-picoseconds to nanoseconds - Trapp_2014_J.R.Soc.Interface_11_
Author(s) : Trapp M , Tehei M , Trovaslet M , Nachon F , Martinez N , Koza MM , Weik M , Masson P , Peters J
Ref : J R Soc Interface , 11 : , 2014
Abstract : It is a long debated question whether catalytic activities of enzymes, which lie on the millisecond timescale, are possibly already reflected in variations in atomic thermal fluctuations on the pico- to nanosecond timescale. To shed light on this puzzle, the enzyme human acetylcholinesterase in its wild-type form and complexed with the inhibitor huperzine A were investigated by various neutron scattering techniques and molecular dynamics simulations. Previous results on elastic neutron scattering at various timescales and simulations suggest that dynamical processes are not affected on average by the presence of the ligand within the considered time ranges between 10 ps and 1 ns. In the work presented here, the focus was laid on quasi-elastic (QENS) and inelastic neutron scattering (INS). These techniques give access to different kinds of individual diffusive motions and to the density of states of collective motions at the sub-picoseconds timescale. Hence, they permit going beyond the first approach of looking at mean square displacements. For both samples, the autocorrelation function was well described by a stretched-exponential function indicating a linkage between the timescales of fast and slow functional relaxation dynamics. The findings of the QENS and INS investigation are discussed in relation to the results of our earlier elastic incoherent neutron scattering and molecular dynamics simulations.
ESTHER : Trapp_2014_J.R.Soc.Interface_11_
PubMedSearch : Trapp_2014_J.R.Soc.Interface_11_
PubMedID: 24872501

Title : Relation between dynamics, activity and thermal stability within the cholinesterase family - Trovaslet_2013_Chem.Biol.Interact_203_14
Author(s) : Trovaslet M , Trapp M , Weik M , Nachon F , Masson P , Tehei M , Peters J
Ref : Chemico-Biological Interactions , 203 :14 , 2013
Abstract : Incoherent neutron scattering is one of the most powerful tools for studying dynamics in biological matter. Using the cold neutron backscattering spectrometer IN16 at the Institut Laue Langevin (ILL, Grenoble, France), temperature dependence of cholinesterases' dynamics (human butyrylcholinesterase from plasma: hBChE; recombinant human acetylcholinesterase: hAChE and recombinant mouse acetylcholinesterase: mAChE) was examined using elastic incoherent neutron scattering (EINS). The dynamics was characterized by the averaged atomic mean square displacement (MSD), associated with the sample flexibility at a given temperature. We found MSD values of hAChE above the dynamical transition temperature (around 200K) larger than for mAChE and hBChE, implying that hAChE is more flexible than the other ChEs. Activation energies for thermodynamical transition were extracted through the frequency window model (FWM) (Becker et al. 2004) [1] and turned out to increase from hBChE to mAChE and finally to hAChE, inversely to the MSDs relations. Between 280 and 316K, catalytic studies of these enzymes were carried out using thiocholine esters: at the same temperature, the hAChE activity was systematically higher than the mAChE or hBChE ones. Our results thus suggest a strong correlation between dynamics and activity within the ChE family. We also studied and compared the ChEs thermal inactivation kinetics. Here, no direct correlation with the dynamics was observed, thus suggesting that relations between enzyme dynamics and catalytic stability are more complex. Finally, the possible relation between flexibility and protein ability to grow in crystals is discussed.
ESTHER : Trovaslet_2013_Chem.Biol.Interact_203_14
PubMedSearch : Trovaslet_2013_Chem.Biol.Interact_203_14
PubMedID: 22940283

Title : Activity and molecular dynamics relationship within the family of human cholinesterases - Peters_2012_Phys.Chem.Chem.Phys_14_6764
Author(s) : Peters J , Trovaslet M , Trapp M , Nachon F , Hill F , Royer E , Gabel F , van Eijck L , Masson P , Tehei M
Ref : Phys Chem Chem Phys , 14 :6764 , 2012
Abstract : The temperature dependence of the dynamics of recombinant human acetylcholinesterase (hAChE) and plasma human butyrylcholinesterase (hBChE) is examined using elastic incoherent neutron scattering. These two enzymes belong to the same family and present 50% amino acid sequence identity. However, significantly higher flexibility and catalytic activity of hAChE when compared to the ones of hBChE are measured. At the same time, the average height of the potential barrier to the motions is increased in the hBChE, e.g. more thermal energy is needed to cross it in the latter case, which might be the origin of the increase in activation energy and the reduction in the catalytic rate of hBChE observed experimentally. These results suggest that the motions on the picosecond timescale may act as a lubricant for those associated with activity occurring on a slower millisecond timescale.
ESTHER : Peters_2012_Phys.Chem.Chem.Phys_14_6764
PubMedSearch : Peters_2012_Phys.Chem.Chem.Phys_14_6764
PubMedID: 22395795

Title : Energy landscapes of human acetylcholinesterase and its huperzine a-inhibited counterpart - Trapp_2012_J.Phys.Chem.B_116_14744
Author(s) : Trapp M , Trovaslet M , Nachon F , Koza MM , van Eijck L , Hill F , Weik M , Masson P , Tehei M , Peters J
Ref : J Phys Chem B , 116 :14744 , 2012
Abstract : Enzymes are animated by a hierarchy of motions occurring on time scales that span more than 15 orders of magnitude from femtoseconds (10(-15) s) to several minutes. As a consequence, an enzyme is characterized by a large number of conformations, so-called conformational substates that interconvert via molecular motions. The energy landscapes of these macromolecules are very complex, and many conformations are separated by only small energy barriers. Movements at this level are fast thermal atomic motions occurring on a time scale between 10(-7) and 10(-12) s, which are experimentally accessible by incoherent neutron scattering techniques. They correspond to local fluctuations within the molecule and are believed to act as coupling links for larger, conformational changes. Several questions related to this hierarchy of motions are a matter of very active research: which of the motions are involved in the biological functions of the macromolecule and are motions of different energy (and thus time) scale correlated? How does the distribution of motions change when an enzyme is inhibited? We report here on investigations of the enzyme human acetylcholinesterase, unliganded and in complex with the noncovalent inhibitor Huperzine A, by incoherent neutron scattering. Different time scales are explored to shed light on the interplay of enzyme activity, dynamics, and inhibition. Surprisingly the average molecular dynamics do not seem to be altered by the presence of the inhibitor used in this study within the considered time scales. The activation energy for the free and the inhibited form of the enzyme is moreover found to be almost identical despite changes of interactions inside the gorge, which leads to the active site of the enzyme.
ESTHER : Trapp_2012_J.Phys.Chem.B_116_14744
PubMedSearch : Trapp_2012_J.Phys.Chem.B_116_14744
PubMedID: 23186408