S-Nitrosated hemoglobin is remarkably stable and can be cycled between deoxy, oxygenated, or oxid... more S-Nitrosated hemoglobin is remarkably stable and can be cycled between deoxy, oxygenated, or oxidized forms without significant loss of NO. Here we show that S-nitrosation of adult human hemoglobin (Hb A(0)) or sickle cell Hb (Hb S) results in an increased ease of anaerobic heme oxidation, while anions cause redox shifts in the opposite direction. The negatively charged groups of the cytoplasmic domain of Band 3 protein also produce an allosteric effect on S-nitrosated Hb. Formation and deoxygenation of a SNO-Hb/Band 3 protein assembly does not in itself cause NO release, even in the presence of glutathione; however, this assembly may play a role in the migration of NO from the red blood cells to other targets and may be linked to Heinz body formation. Studies of the anaerobic oxidation of Hb S revealed an altered redox potential relative to Hb A(0) that favors met-Hb formation and may therefore underlie the increased rate of autoxidation of Hb S under aerobic conditions, the increa...
Proceedings of the National Academy of Sciences, 2003
Although the presence of an exogenous anion is a requirement for tight Fe 3+ binding by the bacte... more Although the presence of an exogenous anion is a requirement for tight Fe 3+ binding by the bacterial ( Neisseria ) transferrin n Fbp, the identity of the exogenous anion is not specific in vitro. n Fbp was reconstituted as a stable iron containing protein by using a number of different exogenous anions [arsenate, citrate, nitrilotriacetate, pyrophosphate, and oxalate (symbolized by X)] in addition to phosphate, predominantly present in the recombinant form of the protein. Spectroscopic characterization of the Fe 3+ /anion interaction in the reconstituted protein was accomplished by UV-visible and EPR spectroscopies. The affinity of the protein for Fe 3+ is anion dependent, as evidenced by the effective Fe 3+ binding constants ( K ′ eff ) observed, which range from 1 × 10 17 M −1 to 4 × 10 18 M −1 at pH 6.5 and 20°C. The redox potentials for Fe 3+ n FbpX/Fe 2+ n FbpX reduction are also found to depend on the identity of the synergistic anion required for Fe 3+ sequestration. Facile ...
While there has been extensive interest in the use of boron isotope ratios as a surrogate of pH i... more While there has been extensive interest in the use of boron isotope ratios as a surrogate of pH in paleoclimate studies in the context of climate change-related questions, the high (0.4 mM) concentration and the depth-independent (conservative or non-nutrient-like) concentration profile of this element have led to boron being neglected as a potentially biologically relevant element in the modern ocean. Here we report that boron affects the expression of a number of protein and genes in the "algal-associated" Gram-negative marine bacterium Marinobacter algicola DG893. Most intriguingly, a number of these proteins and genes are related to iron uptake. In a recent separate publication we have shown that boron regulates one such iron transport related protein, i.e. the periplasmic iron binding protein FbpA via a direct interaction of the metalloid with this protein. Here we show that a number of other iron uptake related genes are also affected by boron but in the opposite way i.e. they are up-regulated. We propose that the differential effect of boron on FbpA expression relative to other iron transport related genes is a result of an interaction between boron and the global iron regulatory protein Fur.
S-Nitrosated hemoglobin is remarkably stable and can be cycled between deoxy, oxygenated, or oxid... more S-Nitrosated hemoglobin is remarkably stable and can be cycled between deoxy, oxygenated, or oxidized forms without significant loss of NO. Here we show that S-nitrosation of adult human hemoglobin (Hb A(0)) or sickle cell Hb (Hb S) results in an increased ease of anaerobic heme oxidation, while anions cause redox shifts in the opposite direction. The negatively charged groups of the cytoplasmic domain of Band 3 protein also produce an allosteric effect on S-nitrosated Hb. Formation and deoxygenation of a SNO-Hb/Band 3 protein assembly does not in itself cause NO release, even in the presence of glutathione; however, this assembly may play a role in the migration of NO from the red blood cells to other targets and may be linked to Heinz body formation. Studies of the anaerobic oxidation of Hb S revealed an altered redox potential relative to Hb A(0) that favors met-Hb formation and may therefore underlie the increased rate of autoxidation of Hb S under aerobic conditions, the increa...
Proceedings of the National Academy of Sciences, 2003
Although the presence of an exogenous anion is a requirement for tight Fe 3+ binding by the bacte... more Although the presence of an exogenous anion is a requirement for tight Fe 3+ binding by the bacterial ( Neisseria ) transferrin n Fbp, the identity of the exogenous anion is not specific in vitro. n Fbp was reconstituted as a stable iron containing protein by using a number of different exogenous anions [arsenate, citrate, nitrilotriacetate, pyrophosphate, and oxalate (symbolized by X)] in addition to phosphate, predominantly present in the recombinant form of the protein. Spectroscopic characterization of the Fe 3+ /anion interaction in the reconstituted protein was accomplished by UV-visible and EPR spectroscopies. The affinity of the protein for Fe 3+ is anion dependent, as evidenced by the effective Fe 3+ binding constants ( K ′ eff ) observed, which range from 1 × 10 17 M −1 to 4 × 10 18 M −1 at pH 6.5 and 20°C. The redox potentials for Fe 3+ n FbpX/Fe 2+ n FbpX reduction are also found to depend on the identity of the synergistic anion required for Fe 3+ sequestration. Facile ...
While there has been extensive interest in the use of boron isotope ratios as a surrogate of pH i... more While there has been extensive interest in the use of boron isotope ratios as a surrogate of pH in paleoclimate studies in the context of climate change-related questions, the high (0.4 mM) concentration and the depth-independent (conservative or non-nutrient-like) concentration profile of this element have led to boron being neglected as a potentially biologically relevant element in the modern ocean. Here we report that boron affects the expression of a number of protein and genes in the "algal-associated" Gram-negative marine bacterium Marinobacter algicola DG893. Most intriguingly, a number of these proteins and genes are related to iron uptake. In a recent separate publication we have shown that boron regulates one such iron transport related protein, i.e. the periplasmic iron binding protein FbpA via a direct interaction of the metalloid with this protein. Here we show that a number of other iron uptake related genes are also affected by boron but in the opposite way i.e. they are up-regulated. We propose that the differential effect of boron on FbpA expression relative to other iron transport related genes is a result of an interaction between boron and the global iron regulatory protein Fur.
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Papers by Alvin Crumbliss