NMR of Paramagnetic Proteins ; 13C Derived Paramagnetic Relaxation Enhancements Are an Additional Source of Structural Information in Solution

Funding Information: This project was supported from the PRIN2020-FAITH (Post-doctoral Fellowship to JMS). This work was funded by National funds through FCT-Fundaҫão para a Ciência e a Tecnologia, I. P. (FCT), project MOSTMICRO-ITQB with refs UIDB/04612/2020 and UIDP/04612/2020, and LS4FUTURE Associated Laboratory (LA/P/0087/2020). This work benefited from access to CERM/CIRMMP, the Instruct-ERIC Italy centre and from COST Action CA21115, supported by COST (European Cooperation in Science and Technology). Publisher Copyright: © 2023 by the authors. ; In paramagnetic metalloproteins, longitudinal relaxation rates of 13C′ and 13Cα nuclei can be measured using 13C detected experiments and converted into electron spin-nuclear spin distance restraints, also known as Paramagnetic Relaxation Enhancement (PRE) restraints. 13C are less sensitive to paramagnetism than 1H nuclei, therefore, 13C based PREs constitute an additional, non-redundant, structural information. We will discuss the complementarity of 13C PRE restraints with 1H PRE restraints in the case of the High Potential Iron Sulfur Protein (HiPIP) PioC, for which the NMR structure of PioC has been already solved by a combination of classical and paramagnetism-based restraints. We will show here that 13C R1 values can be measured also at very short distances from the paramagnetic center and that the obtained set of 13C based restraints can be added to 1H PREs and to other classical and paramagnetism based NMR restraints to improve quality and quantity of the NMR information. ; publishersversion ; published