Enzymes that employ transition metals as co-factors are housed in a wide variety of intracellular locations or are exported to the extracellular milieu. A key question then arises: how are specific metal co-factors transported to diverse locations and subsequently sorted into the correct metalloenzymes? The mechanisms by which these tasks are accomplished are just now being unraveled. A new fam...

The nuclease domain of ColE7 (N-ColE7) contains an H-N-H motif that folds in a beta beta alpha-metal topology. Here we report the crystal structures of a Zn2+-bound N-ColE7 (H545E mutant) in complex with a 12-bp duplex DNA and a Ni2+-bound N-ColE7 in complex with the inhibitor Im7 at a resolution of 2.5 A and 2.0 A, respectively. Metal-dependent cleavage assays showed that N-ColE7 cleaves doubl...

To systematically study the effects of the number of d electrons of the first transition metal ions (Fe, Co, Ni, Cu and Zn) on the formation and stability of metal flavonoid complexes, we took the quercetin/M2+ complex as a model system to investigate the structures and properties of these complexes. Based on considerable structural information obtained through ESI-MSn, all of the first transit...

Besides x-ray fluorescence (XRF) and transition electron microscopy (TEM), 3-dimensional focused ion beam (3D-FIB) combined with scanning electron microscopy (SEM) is an additional method to investigate the transition metal distribution in crystalline silicon material leading to additional information on the 3D shape, size and distribution of precipitates. The 3D-FIB method has been used to inv...

Transition metal oxides form crystals that have phases with exotic properties such as high temperature superconductivity, ferromagnetism, ferroelectricity, and charge and orbital ordering. Often these phases are in competition with each other leading to complicated phase diagrams, for example YBa2Cu3O7, which is a high temperature superconductor, and LaMnO3, which exhibits a “colossal magneto r...

A recombinant trypsin was designed whose catalytic activity can be regulated by varying the concentration of Cu2+ in solution. Substitution of Arg-96 with a His in rat trypsin (trypsin R96H) places a new imidazole group on the surface of the enzyme near the essential active-site His-57. The unique spatial orientation of these His side chains results in the formation of a stable, metal-binding s...

Transition metals are essential for many metabolic processes, and their homeostasis is crucial for life. Metal-ion transporters play a major role in maintaining the correct concentrations of the various metal ions in living cells. Little is known about the transport mechanism of metal ions by eukaryotic cells. Some insight has been gained from studies of the mammalian transporter DCT1 and the y...

The first component of human complement (C1) was reconstituted from equimolar concentrations of its purified subunits C1q, C1r, and C1s, in the presence of each of nine different metal ions for the purpose of studying the qualitative and quantitative nature of the metal ion requirement for C1 assembly and function. For C1 reconstituted with each metal ion, three assays characteristic of C1 were...

Transition metals such as iron, copper, zinc, or molybdenum are essential nutrients for plants. These elements are involved in almost every biological process, including photosynthesis, tolerance to biotic and abiotic stress, or symbiotic nitrogen fixation. However, plants often grow in soils with limiting metallic oligonutrient bioavailability. Consequently, to ensure the proper metal levels, ...