Metal-cation regulation of enzyme dynamics is a key factor influencing the activity of S-adenosyl-L-homocysteine hydrolase from Pseudomonas aeruginosa.

S-adenosyl-L-homocysteine hydrolase from Pseudomonas aeruginosa (PaSAHase) coordinates one K ion and one Zn ion in the substrate binding area. The cations affect the enzymatic activity and substrate binding but the molecular mechanisms of their action are unknown. Enzymatic and isothermal titration calorimetry studies demonstrated that the K ions stimulate the highest activity and strongest ligand binding in comparison to other alkali cations, while the Zn ions inhibit the enzyme activity.

S-adenosyl-L-homocysteine hydrolase from a hyperthermophile (Thermotoga maritima) is expressed in Escherichia coli in inactive form - Biochemical and structural studies.

Thermotoga maritima is a hyperthermophilic bacterium but its genome encodes a number of archaeal proteins including S-adenosyl-L-homocysteine hydrolase (SAHase), which regulates cellular methylation reactions. The question of proper folding and activity of proteins of extremophilic origin is an intriguing problem. When expressed in E.

Tetra-ethyl-ammonium toluene-4-sulfon-ate.

There are two tetra-ethyl-ammonium cations and two toluene-4-sulfate anions in the asymmetric unit of the title salt, C8H20N(+)·C7H7O3S(-). One of the anions is disordered over two positions, with refined occupancies of 0.447 (3) and 0.

Tris(1,10-phenanthroline-κ(2) N,N')ruthenium(II) bis-(perchlorate).

The asymmetric unit of the title compound, [Ru(C12H8N2)3](ClO4)2, contains one octahedrally coordinated Ru(II) cation of the ruthenium-phenanthroline complex and three differently occupied perchlorate anions: two, denoted A and B, are located on the twofold axis while another, denoted C, is positioned in the proximity of the twofold screw axis. Perchlorate anions B and C are severely disordered. The occupancies of the two major conformers of anion B refined to 0.