scholarly journals Solution-State Proton Nuclear Magnetic Resonance (NMR) Spectroscopic Studies of the Active Site of Myoglobins in Various Ligated States: Models for Macromolecule-Substrate Binding and Advancement of Paramagnetic NMR Techniques

2000 ◽  
Author(s):  
Sidney Yee
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Active Site ◽  
Substrate Binding ◽  
Spectroscopic Studies ◽  
Proton Nuclear Magnetic Resonance ◽  
Paramagnetic Nmr ◽  
Solution State ◽  
Nmr Techniques ◽  
Nuclear Magnetic

Identification of Polychlorinated Pyrenes and Pyrene-Addition Products Using Proton Nuclear Magnetic Resonance Techniques

1987 ◽  
Vol 41 (7) ◽  
pp. 1194-1199 ◽  
Author(s):  
David L. Ashley ◽  
Elizabeth R. Barnhart ◽  
Donald G. Patterson ◽  
Robert H. Hill
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Proton Nuclear Magnetic Resonance ◽  
Relaxation Rates ◽  
Spectral Parameters ◽  
Normal Orientation ◽  
Nmr Techniques ◽  
Nuclear Magnetic

Nuclear magnetic resonance (NMR) techniques are used to determine the chlorination pattern on a number of chlorinated pyrenes and pyrene-addition products. Determining chemical shifts, couplings, and longitudinal relaxation rates makes the unequivocal assignment of these molecules possible. Chlorination under the conditions described here were found to follow the normal orientation rules for pyrene. Spectral parameters obtained from these molecules are consistent enough to allow further application to unknown compounds. This should simplify assigning NMR spectra to other chlorinated pyrene standards.

scholarly journals Towards resolving the complex paramagnetic nuclear magnetic resonance (NMR) spectrum of small laccase: assignments of resonances to residue-specific nuclei

2021 ◽  
Vol 2 (1) ◽  
pp. 15-23
Author(s):  
Rubin Dasgupta ◽  
Karthick B. S. S. Gupta ◽  
Huub J. M. de Groot ◽  
Marcellus Ubbink
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Active Site ◽  
Nmr Spectra ◽  
Chemical Exchange ◽  
Streptomyces Coelicolor ◽  
Paramagnetic Nmr ◽  
Exchange Processes ◽  
Nuclear Magnetic

Abstract. Laccases efficiently reduce dioxygen to water in an active site containing a tri-nuclear copper centre (TNC). The dynamics of the protein matrix is a determining factor in the efficiency in catalysis. To probe mobility, nuclear magnetic resonance (NMR) spectroscopy is highly suitable. However, several factors complicate the assignment of resonances to active site nuclei in laccases. The paramagnetic nature causes large shifts and line broadening. Furthermore, the presence of slow chemical exchange processes of the imidazole rings of copper ligand results in peak doubling. A third complicating factor is that the enzyme occurs in two states, the native intermediate (NI) and resting oxidized (RO) states, with different paramagnetic properties. The present study aims at resolving the complex paramagnetic NMR spectra of the TNC of Streptomyces coelicolor small laccase (SLAC). With a combination of paramagnetically tailored NMR experiments, all eight His Nδ1 and Hδ1 resonances for the NI state are identified, as well as His Hβ protons for the RO state. With the help of second-shell mutagenesis, selective resonances are tentatively assigned to the histidine ligands of the copper in the type-2 site. This study demonstrates the utility of the approaches used for the sequence-specific assignment of the paramagnetic NMR spectra of ligands in the TNC that ultimately may lead to a description of the underlying motion.

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