Search results for "ZINC"

COBALT SUBSTITUTED PROTEINS

1995

Cobalt(II) has been extensively used as a spectroscopic probe in many proteins, mainly replacing zinc, but also substituting iron, manganese and copper ions. The relatively short electronic relaxation times of high spin cobalt(II) makes this ion suitable as a paramagnetic probe for Nuclear Magnetic Resonance spectroscopy. A survey of the NMR studies performed in cobalt substituted proteins is shown. In the zinc enzymes Carboxypeptidase A, Carbonic Anhydrase and Superoxide Dismutase the implications of these studies on their catalytic mechanisms are commented. Finally, a further insight in the research of the blue copper protein Azurin by applying NMR to its cobalt derivative is also reporte…

Singlet and triplet energy transfers in tetra-(meso-truxene)zinc(II)- and tetra-(meso-tritruxene)zinc(II) porphyrin and porphyrin-free base dendrimer…

2011

The synthesis, optical properties, and energy transfer features of four dendrimers composed of meso-tetrasubstituted zinc(II) porphyrin (ZnP) or a free base (P) central core, where the substituents are four truxene (Tru) or four tritruxene dendrons (TriTru), TruP, TriTruP, TruZnP, and TriTruZnP, are reported. Selective excitation of the truxene donors results in a photoinduced singlet energy transfer from the truxenes to the porphyrin acceptor. The rates for singlet energy transfer (k(ET)), evaluated from the change in the fluorescence lifetime of the donors (Tru and TriTru) in the presence and absence of the acceptor (P or ZnP) for TruP, TruZnP, TriTruP, and TriTruZnP, are 5.9, 1.2, 0.87, …

Biosorption of lead(II), zinc(II) and nickel(II) from industrial wastewater by Stenotrophomonas maltophilia and Bacillus subtilis

2015

Abstract The biosorption of Pb(II), Zn(II) and Ni(II) from industrial wastewater using Stenotrophomonas maltophilia and Bacillus subtilis was investigated under various experimental conditions regarding pH, metal concentration and contact time. The optimum pH values for the biosorption of the three metals were in the range 5.0-6.0, while the optimal contact time for the two bacterial species was 30 min. Experimental data was analyzed using Langmuir and Freundlich isotherms; the former had a better fit for the biosorption of Pb(II), Zn(II) and Ni(II). The maximum adsorption uptakes (qmax) of the three metals calculated from the Langmuir biosorption equation for S. maltophilia were 133.3, 47.…

New Porphycene Ligands: Octaethyl- and Etioporphycene(OEPc and EtioPc)—Tetra- and Pentacoordinated Zinc Complexes of OEPc

1993

Iron and zinc bioavailability in Caco-2 cells: Influence of caseinophosphopeptides

2013

Abstract A study has been made of the influence of two pools of caseinophosphopeptides (CPPs) obtained from α s - and β-casein (CN) fractions, and of three specific CPPs (β-CN(1–25)4P, α s1 -CN(64–74)4P and α s2 -CN(1–19)4P), on iron bioavailability (ferritin synthesis) and zinc bioavailability (retention, transport and uptake of zinc) in Caco-2 cells. α-CPP and β-CPP pools did not improve ferritin synthesis, but the three specific CPPs showed an increase in ferritin synthesis in Caco-2 cells versus iron sulphate, β-CN(1–25)4P being the most effective. In relation to zinc bioavailability, α-CPPs, β-CPPs, α s1 -CN(64–74)4P and β-CN(1–25)4P increased zinc uptake. However, this increase was of…

Seasonal Variation in Nutrient Status of Foxglove Leaves

2006

The seasonal variation of mineral elements and the relationships among them were studied in natural populations of foxglove (Digitalis obscura). Young and mature leaves were collected in 10 different populations and on four sample dates (May, July, October, and February). Leaf mineral elements [nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu)] were determined. The highest concentrations of N, P, and K in young leaf were recorded in May, followed by a decrease in the other months, while in contrast Ca and Fe showed the lowest concentration in May. Mature leaves showed differential seasonal behavior. Besides seaso…

Movement of Metals to New Growing Tissue in the MossHylocomium splendens(Hedw.) BSG

1997

To obtainHylocomium splendens(Hedw.) BSG. that varied in metal (K, Mg, Ca and Zn) content, moss samples were collected from six sites around a zinc contaminated area of Latvia; metal contents were artificially lowered by branch excision. The first fully expanded annual segment (mature segments), together with the unexpanded segment (juvenile segment) were grown in the laboratory with watering from below. The contents of K, Mg, Ca and Zn in new growth were correlated with initial contents in the juvenile+mature segments. However, the concentrations of these metals in the new growth were generally not correlated with those in the pre-experimental segments. The excision of branches from the ma…

Metal specificity of the Ni(II) and Zn(II) binding sites of the N-terminal and G-domain of E. coli HypB

2021

HypB is one of the chaperones required for proper nickel insertion into [NiFe]-hydrogenase. Escherichia coli HypB has two potential Ni(II) and Zn(II) binding sites—the N-terminal one and the so-called GTPase one. The metal-loaded HypB–SlyD metallochaperone complex activates nickel release from the N-terminal HypB site. In this work, we focus on the metal selectivity of the two HypB metal binding sites and show that (i) the N-terminal region binds Zn(II) and Ni(II) ions with higher affinity than the G-domain and (ii) the lower affinity G domain binds Zn(II) more effectively than Ni(II). In addition, the high affinity N-terminal domain, both in water and membrane mimicking SDS solution, has a…

CCDC 829874: Experimental Crystal Structure Determination

2012

Related Article: R.Inglis, E.Houton, Junjie Liu, A.Prescimone, J.Cano, S.Piligkos, S.Hill, L.F.Jones, E.K.Brechin|2011|Dalton Trans.|40|9999|doi:10.1039/c1dt11118c

CCDC 736124: Experimental Crystal Structure Determination

2010

Related Article: R.Ballesteros-Garrido, B.Abarca, R.Ballesteros, C.R.de Arellano, F.R.Leroux, F.Colobert, E.Garcia-Espana|2009|New J.Chem.|33|2102|doi:10.1039/b906992e