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@INPROCEEDINGS{Schrader:1053145,
author = {Schrader, Tobias Erich and Ostermann},
title = {{WHAT} {NEUTRONS} {CAN} {DO} {FOR} {YOU}:{THE} {SINGLE}
{CRYSTAL} {NEUTRON} {DIFFRACTOMETER} {BIODIFF} {AT} {THE}
{HEINZ} {MAIER}-{LEIBNITZ} {ZENTRUM}},
reportid = {FZJ-2026-01477},
year = {2025},
abstract = {Neutrons are scattered from the nuclei and x-rays are
scattered from the electrons of the atoms in a protein
crystal. This renders these two scattering probes as being
complementary to each other. The neutrons can see the
hydrogen atom positions in a protein crystal. This allows to
determine protonation states of crucial amino acid residues
in the active centre of an enzyme or one can detect water
clusters and proton paths to the active centre by locating
water molecules and their exact orientation and hydrogen
bonding. In this contribution neutron protein
crystallography is introduced using the example of alcohol
dehydrogenase from the organism Lactobacillus brevis
(LbADH), an enzyme which catalyzes the reduction of
prochiral ketones to the corresponding secondary alcohols
[1]. The data set for this project was taken with the
instrument BIODIFF. The neutron single crystal
diffractometer BIODIFF at the research reactor Heinz
Maier-Leibnitz (FRM II) is especially designed to collect
data from crystals with large unit cells. The main field of
application is the structural analysis of proteins,
especially the determination of hydrogen atom positions.
BIODIFF is a joint project of the Jülich Centre for Neutron
Science (JCNS) and the FRM II. BIODIFF is designed as a
monochromatic instrument with a narrow wavelength spread of
less than 3 $\%.$ To cover a large solid angle the main
detector of BIODIFF consists of a neutron imaging plate in a
cylindrical geometry with online read-out capability. The
resulting data led to a better understanding of the role of
the Magnesium ion in substrate binding and it showed a new
hydrogen bonding network close to the active centre of the
enzyme. It also showed nicely the complementary nature of
x-ray and neutron protein crystallography. The metal ion in
Figure 1 has not been detected by neutron scattering but it
was easily seen by x-ray scattering. The reason for this
lies in a cancellation effect between the negative
scattering length of Manganese ions and the average positive
scattering lengths of Magnesium ions which just cancel to
zero in this position. The Magnesium ions were present in
the crystallization condition, but the Manganese Ions must
stem from the expression of the protein in the E.coli
expression system.},
month = {Oct},
date = {2025-10-20},
organization = {Enzyme Engineering Conference,
Helsingor (Denmark), 20 Oct 2025 - 24
Oct 2025},
subtyp = {After Call},
cin = {JCNS-FRM-II / MLZ / JCNS-4},
cid = {I:(DE-Juel1)JCNS-FRM-II-20110218 / I:(DE-588b)4597118-3 /
I:(DE-Juel1)JCNS-4-20201012},
pnm = {6G4 - Jülich Centre for Neutron Research (JCNS) (FZJ)
(POF4-6G4) / 632 - Materials – Quantum, Complex and
Functional Materials (POF4-632)},
pid = {G:(DE-HGF)POF4-6G4 / G:(DE-HGF)POF4-632},
experiment = {EXP:(DE-MLZ)BIODIFF-20140101},
typ = {PUB:(DE-HGF)24},
url = {https://juser.fz-juelich.de/record/1053145},
}