The activity of ribonuclease increases with increasing concentration of added divalent metal ions until the attainment of an optimal metal concentration, beyond which the addition of further metal ions inhibits the reaction. When either the optimal metal concentration or the enzymatic activity at that concentration is plotted versus the atomic number of the transition metals, the resulting curv...

The viability of living systems depends inextricably on enzymes that catalyze phosphoryl transfer reactions. For many enzymes in this class, including several ribozymes, divalent metal ions serve as obligate cofactors. Understanding how metal ions mediate catalysis requires elucidation of metal ion interactions with both the enzyme and the substrate(s). In the Tetrahymena group I intron, previo...

Many enzymes use metal ions within their active sites to achieve enormous rate acceleration. Understanding how metal ions mediate catalysis requires elucidation of metal ion interactions with both the enzyme and the substrate(s). The three-dimensional arrangement determined by X-ray crystallography provides a powerful starting point for identifying ground state interactions, but only functional...

Proteins obtained from agricultural sources were blended with divalent metal ions to see if binding reactions occurred between protein chains. Feather keratin, egg albumin, and wheat gluten showed elastic modulus increases of 2–3 times with addition of divalent transition metal ions Cu2þ and Zn2þ. Increasing concentrations of ions resulted in increased stiffness. Birefringence experiments perfo...

Design of a paramagnetic metal binding motif in a protein is a valuable way for understanding the function, dynamics and interactions of a protein by paramagnetic NMR spectroscopy. Several strategies have been proposed to site-specifically tag proteins with paramagnetic lanthanide ions. Here we report a simple approach of engineering a transition metal binding motif via site-specific labelling ...

Mercury ion (Hg2+) is recognized as one of the most toxic metal ions for the environment and for human health. Techniques utilized in the detection of Hg2+ are an important factor. Herein, a simple thymine was successfully employed as the surface enhanced Raman spectroscopy sensor for Hg2+ ion detection. The limit of detection (LOD) of the developed sensor is better than 0.1 nM (0.02 ppb). This...

Transition metal ions have their own significances and utility. Externally applied pesticides may alter the bioavailability of these metal ions to plants through the coordinating ability of these pesticides with metal ions. In current study a series of metal complexes containing atrazine (Atr) group(s) attached to metal(II) (M) frame, with the formula; [M(Atr)n.xH2O.yCl] (where M = Mn, Fe, Co, ...

Imidase catalyzes the hydrolysis of a variety of imides. The removal of metal from imidase eliminates its activity but does not affect its tetrameric and secondary structure. The reactivation of the apoenzyme with transition metal ions Co(2+), Zn(2+), Mn(2+), and Cd(2+) shows that imidase activity is linearly dependent on the amount of metal ions added. Ni(2+) and Cu(2+) are also inserted, one ...

Porphyrins are a group of tetrapyrrole pigments. Physical and chemical properties of porphyrins are often related to their compositions and structures. We conducted 1H solution NMR and UV-visible spectral analysis to characterize the structural feature of a water-soluble, synthetic porphyrin i.e. tetrakis (p-sulfonatophenyl) porphyrin, TPPS4, and its interaction with different metal ions in aqu...

The hairpin ribozyme comprises two formally unpaired loops carried on two arms of a four-way helical RNA junction. Addition of divalent metal ions brings about a conformational transition into an antiparallel structure in which there is an intimate association between the loops to generate the active form of the ribozyme. In this study, we have used fluorescence resonance energy transfer to ana...