NMR of Paramagnetic Proteins: [sup.13]C Derived Paramagnetic Relaxation Enhancements Are an Additional Source of Structural Information in Solution

• Published in: Magnetochemistry Vol. 9; no. 3
• Main Authors: Querci, Leonardo, Trindade, Inês B, Invernici, Michele, Silva, José Malanho, Cantini, Francesca, Louro, Ricardo O, Piccioli, Mario
• Format: Journal Article
• Language: English
• Published: MDPI AG 01.03.2023
• Subjects: Analysis; Identification and classification; Magnetic properties; Metalloproteins; Nuclear magnetic resonance; Spectra; Italy; Portugal
• ISSN: 2312-7481; 2312-7481
• DOI: 10.3390/magnetochemistry9030066

In paramagnetic metalloproteins, longitudinal relaxation rates of [sup.13]C′ and [sup.13]C[sup.α] nuclei can be measured using [sup.13]C detected experiments and converted into electron spin-nuclear spin distance restraints, also known as Paramagnetic Relaxation Enhancement (PRE) restraints. [sup.13]C are less sensitive to paramagnetism than [sup.1]H nuclei, therefore, [sup.13]C based PREs constitute an additional, non-redundant, structural information. We will discuss the complementarity of [sup.13]C PRE restraints with [sup.1]H 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 [sup.13]C R[sub.1] values can be measured also at very short distances from the paramagnetic center and that the obtained set of [sup.13]C based restraints can be added to [sup.1]H PREs and to other classical and paramagnetism based NMR restraints to improve quality and quantity of the NMR information.