scholarly journals The Divalent Metal Ion in the Active Site of Uteroferrin Modulates Substrate Binding and Catalysis

2010 ◽  
Vol 132 (20) ◽  
pp. 7049-7054 ◽  
Author(s):  
Nataša Mitić ◽  
Kieran S. Hadler ◽  
Lawrence R. Gahan ◽  
Alvan C. Hengge ◽  
Gerhard Schenk
Keyword(s):  
Active Site ◽  
Metal Ion ◽  
Substrate Binding ◽  
Divalent Metal ◽  
Divalent Metal Ion

scholarly journals Structural characterization of tartrate dehydrogenase: a versatile enzyme catalyzing multiple reactions

2010 ◽  
Vol 66 (6) ◽  
pp. 673-684 ◽  
Author(s):  
Radhika Malik ◽  
Ronald E. Viola
Keyword(s):  
Active Site ◽  
Metal Ion ◽  
Substrate Binding ◽  
Hydride Transfer ◽  
Divalent Metal ◽  
Ammonium Ion ◽  
Hydroxyl Group ◽  
Metal Ion Binding ◽  
Cofactor Binding ◽  
Divalent Metal Ion

The first structure of an NAD-dependent tartrate dehydrogenase (TDH) has been solved to 2 Å resolution by single anomalous diffraction (SAD) phasing as a complex with the intermediate analog oxalate, Mg2+and NADH. This TDH structure fromPseudomonas putidahas a similar overall fold and domain organization to other structurally characterized members of the hydroxy-acid dehydrogenase family. However, there are considerable differences between TDH and these functionally related enzymes in the regions connecting the core secondary structure and in the relative positioning of important loops and helices. The active site in these complexes is highly ordered, allowing the identification of the substrate-binding and cofactor-binding groups and the ligands to the metal ions. Residues from the adjacent subunit are involved in both the substrate and divalent metal ion binding sites, establishing a dimer as the functional unit and providing structural support for an alternating-site reaction mechanism. The divalent metal ion plays a prominent role in substrate binding and orientation, together with several active-site arginines. Functional groups from both subunits form the cofactor-binding site and the ammonium ion aids in the orientation of the nicotinamide ring of the cofactor. A lysyl amino group (Lys192) is the base responsible for the water-mediated proton abstraction from the C2 hydroxyl group of the substrate that begins the catalytic reaction, followed by hydride transfer to NAD. A tyrosyl hydroxyl group (Tyr141) functions as a general acid to protonate the enolate intermediate. Each substrate undergoes the initial hydride transfer, but differences in substrate orientation are proposed to account for the different reactions catalyzed by TDH.

Mutational Analysis of Divalent Metal Ion Binding in the Active Site of Class II α-Mannosidase from Sulfolobus solfataricus

Biochemistry ◽  
2015 ◽  
Vol 54 (11) ◽  
pp. 2032-2039 ◽  
Author(s):  
Dennis K. Hansen ◽  
Helen Webb ◽  
Jonas Willum Nielsen ◽  
Pernille Harris ◽  
Jakob R. Winther ◽  
...  
Keyword(s):  
Active Site ◽  
Metal Ion ◽  
Mutational Analysis ◽  
Sulfolobus Solfataricus ◽  
Class Ii ◽  
Divalent Metal ◽  
Ion Binding ◽  
Metal Ion Binding ◽  
Divalent Metal Ion

Structural and thermodynamic insights into a novel Mg2+–citrate-binding protein from the ABC transporter superfamily

2021 ◽  
Vol 77 (12) ◽  
Author(s):  
Suraj Kumar Mandal ◽  
Shankar Prasad Kanaujia
Keyword(s):  
Metal Ions ◽  
Abc Transporter ◽  
Metal Ion ◽  
Binding Protein ◽  
Substrate Binding ◽  
Divalent Metal ◽  
Uptake System ◽  
Divalent Metal Ions ◽  
Gram Negative ◽  
Divalent Metal Ion

More than one third of proteins require metal ions to accomplish their functions, making them obligatory for the growth and survival of microorganisms in varying environmental niches. In prokaryotes, besides their involvement in various cellular and physiological processes, metal ions stimulate the uptake of citrate molecules. Citrate is a source of carbon and energy and is reported to be transported by secondary transporters. In Gram-positive bacteria, citrate molecules are transported in complex with divalent metal ions, whereas in Gram-negative bacteria they are translocated by Na+/citrate symporters. In this study, the presence of a novel divalent-metal-ion-complexed citrate-uptake system that belongs to the primary active ABC transporter superfamily is reported. For uptake, the metal-ion-complexed citrate molecules are sequestered by substrate-binding proteins (SBPs) and transferred to transmembrane domains for their transport. This study reports crystal structures of an Mg2+–citrate-binding protein (MctA) from the Gram-negative thermophilic bacterium Thermus thermophilus HB8 in both apo and holo forms in the resolution range 1.63–2.50 Å. Despite binding various divalent metal ions, MctA possesses the coordination geometry to bind its physiological metal ion, Mg2+. The results also suggest an extended subclassification of cluster D SBPs, which are known to bind and transport divalent-metal-ion-complexed citrate molecules. Comparative assessment of the open and closed conformations of the wild-type and mutant MctA proteins suggests a gating mechanism of ligand entry following an `asymmetric domain movement' of the N-terminal domain for substrate binding.

New divalent metal ion complexes with 1,8-diaminonapthalene -2-thione: Synthesis, Spectroscopic, anti-bacterial and anticancer activity studies

2021 ◽  
pp. 131291
Author(s):  
Ahmed S. Faihan ◽  
Mohammad R. Hatshan ◽  
Ali S. Alqahtani ◽  
Fahd A. Nasr ◽  
Subhi A. Al-Jibori ◽  
...  
Keyword(s):  
Anticancer Activity ◽  
Metal Ion ◽  
Divalent Metal ◽  
Metal Ion Complexes ◽  
Divalent Metal Ion

Divalent metal ion-sensitive holographic sensors

2005 ◽  
Vol 528 (2) ◽  
pp. 219-228 ◽  
Author(s):  
Blanca Madrigal González ◽  
Graham Christie ◽  
Colin A.B. Davidson ◽  
Jeff Blyth ◽  
Christopher R. Lowe
Keyword(s):  
Metal Ion ◽  
Divalent Metal ◽  
Divalent Metal Ion
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