Magnesium ions structure stabilizers

The use of alkali and alkaline earth group metal ions, especially those of sodium, potassium, magnesium, and calcium, for maintenance of electrolyte balance and for signaling and promotion of enzyme activity and protein function are not discussed in this text. Many of these ions, used for signaling purposes in the exciting area of neuroscience, are of great interest. In ribozymes, RNAs with catalytic activity, solvated magnesium ions stabilize complex secondary and tertiary molecular structure. Telomeres, sequences of DNA at the ends of chromosomes that are implicated in cell death or immortalization, require potassium ions for structural stabilization. 

R. H., Draper, D. E. The RNA-binding domain of ribosomal protein Lll recognizes an rRNA tertiary structure stabilized by both fhiostrepton and magnesium ion. Nucleic Adds Res 2000, 28, 1778—... 

Much structural biology analysis has been performed on protein kinase A (PKA), and its catalytic residues are conserved across the family (6, 7). In PKA, lysine 72 and glutamate 91 orient the y-phosphate toward the protein substrate (Fig. 2b). Aspartate 166 acts as a catalytic base to accept the proton from the hydroxyl nucleophile, and Lys 168 acts as an electrostatic catalyst to stabilize the y-phosphate during the reaction. Asparagine 171 positions a magnesium ion that coordinates the a/fi phosphates (Fig. 2b). 

Figure 2 Snapshots of the overall structure and catalytic machinery of protein kinase A. (a) The overall fold of the catalytic domain is formed by two subdomains, a beta sheet N-terminus (gray) and a C-terminal helical domain (green). ATP binds a cleft between the two lobes, and the phosphoacceptor substrate binds the C-terminal lobe, (b) N-terminal residues Lys 72 and Glu 91 orient the phosphates toward the phosphoacceptor peptide (pink/yellow) in concert with one of two magnesium ions, (c) C-terminal residue Lys 168 acts as an electrostatic catalyst to stabilize the y-phosphate during the reaction while asparagine 171 and aspartate 184 position the phosphates within the active site.

Single-stranded nucleic acids can adopt structures more complex than simple stem-loops through the interaction of more widely separated bases. Often, three or more bases may interact to stabilize these structures. In such cases, hydrogen-bond donors and acceptors that ordinarily participate in Watson-Crick base pairs may participate in hydrogen bonds of nonstandard pairings. Metal ions such as magnesium ion (Mg2+) often assist in the stabilization of these more elaborate structures. 

We found these conditions by introducing surface-active materials to a solution of a specially prepared catalytic complex containing molybdenum and stabilized by magnesium ions [22]. The structure of the complex which was isolated from the solution in its oxidized form is presented on Figure 5 [23]. When it is reduced to the Mo state the complex becomes an active catalyst of dinitrogen reduction to hydrazine and ammonia by sodium amalgam. Phospholipid (phosphatidylcholine)... 

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