Claudia A Blindauer

The University of Warwick · Department of Chemistry

The initiation, maintenance and regulation of blood coagulation is inexorably linked to the actions of Zn2+ in blood plasma. Zn2+ interacts with a variety of haemostatic proteins in the bloodstream including fibrinogen, histidine-rich glycoprotein (HRG) and high molecular weight kininogen (HMWK) to regulate haemostasis. The availability of Zn2+ to...

Marine cyanobacteria are critical players in global nutrient cycles that crucially depend on trace metals in metalloenzymes, including zinc for CO2 fixation and phosphorus acquisition. How strains proliferating in the vast oligotrophic ocean gyres thrive at ultra-low zinc concentrations is currently unknown. Using Synechococcus sp. WH8102 as a mode...

The speciation of essential metal ions in biological fluids, such as blood plasma and serum, is of fundamental importance to understand the homeostasis of these elements. The activity of metal ions such as Zn²⁺ in extracellular media is thought to affect their interaction with membrane-bound transporters, and thus is critical for their cellular upt...

The role of the extracellular medium in influencing metal uptake into cells has not been described quantitatively. In a chemically-defined model system containing albumin, zinc influx into endothelial cells correlates...

Bacterial metallothioneins are known for a limited range of phyla including cyanobacteria. We have characterised the BmtA from the marine cyanobacterium Synechococcus sp. WH8102 (SynBmtA). This strain inhabits the open ocean, one of the most nutrient-poor environments on Earth, with very low total and free Zn²⁺ concentrations. Therefore, the presen...

The study of chemical speciation and the refinement and expansion of omics-based methods are both consolidated and highly active research fields. Although well established, such fields are extremely dynamic and are driven by the emergence of new strategies and improvements in instrumentation. In the case of omics-based studies, subareas including l...

Protonation equilibria for the parent compound of three highly potent antivirals have been studied by ¹ H NMR spectroscopy.

Decompensated liver cirrhosis has a dismal prognosis, with patients surviving on average for 2–4 years after the first diagnosis of ascites. Albumin is an important tool in the therapy of cirrhotic ascites. By virtue of its oncotic properties, it reduces the risk of cardiovascular dysfunction after paracentesis. Treatment with albumin also countera...

Insulin is stored within the pancreas in an inactive Zn²⁺-bound hexameric form prior to release. Similarly, clinical insulins contain Zn²⁺ and form multimeric complexes. Upon release from the pancreas or upon injection, insulin only becomes active once Zn²⁺ disengages from the complex. In plasma and other extracellular fluids, the majority of Zn²⁺...

Thrombosis is a major comorbidity of obesity and type-2 diabetes mellitus (T2DM). Despite the development of numerous effective treatments and preventative strategies to address thrombotic disease in such individuals, the incidence of thrombotic complications remains high. This suggests that not all the pathophysiological mechanisms underlying thes...

Zn2+ is an essential regulator of coagulation and is released from activated platelets. In plasma, free Zn2+ concentration is fine-tuned through buffering by human serum albumin (HSA). Importantly, the ability of HSA to bind/buffer Zn2+ is compromised by co-transported non-esterified fatty acids (NEFAs). Given the role of Zn2+ in blood clot formati...

Serum albumin is a highly abundant plasma protein associated with the transport of metal ions, pharmaceuticals, fatty acids and a variety of small molecules in the blood. Once thought of as a molecular ‘sponge’, mounting evidence suggests that the albumin-facilitated transport of chemically diverse entities is not independent. One such example is t...

Acyclic nucleoside phosphonates are of medical relevance and deserve detailed chemical characterization. We focus here on (S)‐9‐[3‐hydroxy‐2‐(phosphonomethoxy)propyl]adenine (HPMPA) and include for comparison 9‐[2‐(phosphonomethoxy)ethyl]adenine (PMEA), as well as the nucleobase‐free (phosphonomethoxy)ethane (PME) and (R)‐hydroxy‐2‐(phosphonomethox...

Zn ²⁺ is an essential regulator of coagulation and its availability in plasma is fine-tuned through buffering by human serum albumin (HSA). Non-esterified fatty acids (NEFAs) transported by HSA reduce its ability to bind/buffer Zn ²⁺ . This is important as plasma NEFA levels are elevated in type-2 diabetes mellitus (T2DM) and other diseases with an...

Type 2 diabetes mellitus (T2DM) is associated with increased total plasma free fatty acid (FFA) concentrations and an elevated risk of cardiovascular disease. The exact mechanisms by which the plasma FFA profile of subjects with T2DM changes is unclear, but it is thought that dietary fats and changes to lipid metabolism are likely to contribute. Th...

Four highly similar genes (W08E12.2, W08E12.3, W08E12.4 and W08E12.5) which are consecutively aligned on chromosome IV of the C. elegans genome are predicted to code for small (120-141aa) yet cysteine rich (18-19 cysteines) proteins. Cloning and sequencing of the genomic regions of the isoforms confirmed the presence and order of all genes. The gen...

In mammalian blood plasma, serum albumin acts as a transport protein for free fatty acids, other lipids and hydrophobic molecules including neurodegenerative peptides, and essential metal ions such as zinc to allow their systemic distribution. Importantly, binding of these chemically extremely diverse entities is not independent, but linked alloste...

The problem of handling zinc in the cell is of great importance because zinc is an indispensable micronutrient involved in most physiological processes in all living organisms. Moreover, our understanding of mechanisms governing the discrimination between micronutrients and toxic metals on the level of individual proteins to the whole-organism leve...

All organisms must regulate the cellular uptake, efflux, and intracellular trafficking of essential elements, including d-block metal ions. In bacteria, such regulation is achieved by the action of metal-responsive transcriptional regulators. Among several families of zinc-responsive transcription factors, the 'zinc uptake regulator' Zur is the mos...

Acyclic nucleoside phosphonates (ANPs) are of medical relevance and deserve detailed chemical characterization. We focus here on 1-[2-(phosphonomethoxy)ethyl]cytosine (PMEC), (S)-1-[3-hydroxy-2-(phosphonomethoxy)propyl]cytosine (HPMPC), 9-[2-(phosphonomethoxy)ethyl]adenine (PMEA), and (S)-9-[3-hydroxy-2-(phosphonomethoxy)propyl]adenine (HPMPA) and...

Myocardial ischemia is difficult to diagnose effectively with still few well-defined biochemical markers for identification in advance, or in the absence of myocardial necrosis. “Ischemia-modified albumin” (IMA), a form of albumin displaying reduced cobalt-binding affinity, is significantly elevated in ischemic patients, and the albumin cobalt-bind...

Zinc modulates the biological function of histidine-rich glycoprotein (HRG) through binding to its His-rich region (HRR). The Zn2+-binding properties of a 35 amino-acid biologically-active peptide mimic of the HRR, HRGP330, were investigated using dissociative mass spectrometry approaches in addition to travelling-wave ion mobility mass spectrometr...

The dynamics of metal binding to and transfer from metalloproteins involved in metal homeostasis are important for understanding cellular distribution of metal ions. The dicotyledonous plant Arabidopsis thaliana has two type 4 seed-specific metallothionein homologues, MT4a and MT4b, with likely roles in zinc(II) homeostasis. These two metallothione...

Anthropogenic pollution with heavy metals is an on-going concern throughout the world, and methods to monitor release and impact of heavy metals are of high importance. With a view to probe its suitability as molecular biomarker of metal pollution, this study has determined a coding sequence for metallothionein of the African sharptooth catfish Cla...

Zambia’s Kafue River receives wastes from various sources, resulting in metal pollution. This study determined the degree of contamination of 13 metals (Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Cd, Hg and Pb) in Kafue River sediment and the associated ecological risks at six sites in three different seasons. The level of contamination for most metal...

The lectin DLasiL was isolated from seeds of the Dioclea lasiocarpa collected from the northeast coast of Brazil and characterized for the first time by mass spectrometry, DNA sequencing, ICP-MS, EPR, and fluorescence spectroscopy. The structure of DLasiL lectin obtained by homology modelling suggested strong conservation of the dinuclear Ca/Mn and...

The acyclic nucleoside phosphonate (S)-1-[3-hydroxy-2-(phosphonomethoxy)propyl]cytosine (HPMPC; Cidofovir) has been approved for clinical use in antiviral therapy. We determined the acidity constants of H2(HPMPC)±, as well as that of the nucleobase-free (hydroxy-2-(phosphonomethoxy)propane (H(HPMP)–) (I = 0.1 M, NaNO3; 25°C). Given that in vivo nuc...

Although protein structure has been studied for many decades it remains the case that we cannot state with confidence whether two samples have the same molecular structure, particularly in solution. The increasing number of biosimilar biopharmaceutical drugs that are being tested means this is not an academic exercise. In this work we consider how...

Zinc is an essential nutrient in the body; it is required for the catalytic activity of many hundreds of human enzymes and virtually all biological processes, therefore its homeostasis and trafficking is of crucial interest. Serum albumin is the major carrier of Zn²⁺ in the blood and is required for its systemic distribution. Here we present the fi...

Bacterial trimethylamine N-oxide (TMAO) demethylase, Tdm, carries out an unusual oxygen-independent demethylation reaction, resulting in the formation of dimethylamine and formaldehyde. In this study, site-directed mutagenesis, homology modelling and metal analyses by inorganic mass spectrometry have been applied to gain insight into metal stoichio...

Oxytocin, a cyclic nine amino acid neurohypophyseal hormone therapeutic, is effectively used in the control of postpartum hemorrhaging (PPH) and is on the WHO List of Essential Medicines. However, oxytocin has limited shelf life stability in aqueous solutions, particularly at temperatures in excess of 25 °C and injectable aqueous oxytocin formulati...

With the increased incidence of tuberculosis (TB) caused by Mycobacterium tuberculosis there is an urgent need for new and better anti-tubercular drugs. N-succinyl-L,L-diaminopimelic acid desuccinylase (DapE) is a key enzyme in the succinylase pathway for the biosynthesis of meso-diaminopimelic acid (meso-DAP) and L-lysine. DapE is a zinc containin...

uman serum albumin (HSA) is the major protein in blood plasma and is responsible for circulatory transport of a range of small molecules including fatty acids, metal ions and drugs. We previously identified the major plasma Zn2+ transport site on HSA and revealed that fatty-acid binding (at a distinct site called the FA2 site) and Zn2+ binding are...

Metallothioneins may protect against the chemical toxicity of uranium; thus, we have studied interactions between the cyanobacterial metallothionein SmtA and uranyl. While no uranyl complexes formed with fully or partially demetalated SmtA, its folded, fully zinc-metalated form bound uranyl even in the presence of large excesses of highly competiti...

Earthworms express, as most animals, metallothioneins (MTs)-small, cysteine-rich proteins that bind d(10) metal ions (Zn(II), Cd(II), or Cu(I)) in clusters. Three MT homologues are known for Lumbricus rubellus, the common red earthworm, one of which, wMT-2, is strongly induced by exposure of worms to cadmium. This study concerns composition, metal...

The cellular prion protein has been identified as a metalloprotein that binds copper. There have been some suggestions that prion protein also influences zinc and manganese homeostasis. In this study we used a series of cell lines to study the levels of zinc and manganese under different conditions. We overexpressed either the prion protein or know...

We read with interest the recent article by Giannone et al. where the use of ischaemia-modified albumin (IMA) as a molecular marker of bacterial infection in patients with cirrhosis was assessed [1]. IMA corresponds to a "modified" form of albumin that exhibits reduced ability to bind Co(2+) (with its presence associated with certain medical condit...

The acyclic nucleoside phosphonate (ANP2−) 9-[2-(phosphonomethoxy)ethyl]guanine (PMEG) is anticancer and antivirally active. The acidity constants of the threefold protonated H3(PMEG)+ were determined by potentiometric pH titrations (aq. sol.; 25 °C; I = 0.1 M, NaNO3). Under the same conditions and by the same method, the stability constants of the...

Between 5 and 10% of all proteins of a given organism are estimated to require zinc for function, and hence zinc is essential for almost any given metabolic process. It is therefore of great interest to understand major players and mechanisms that ensure the tight and correct control of zinc distribution and speciation in organisms and their indivi...

Alignment of human and rabbit HRG amino acid sequences. Fig. S2. Full ITC data (including raw data) for Zn2+ binding to rabbit HRG. Fig. S3. ITC data showing the interaction between HSA and Zn2+ in the presence of 0–5 mol eq. of myristate. Fig. S4. Predicted unbound Zn2+ concentrations in the presence of 0–5 mol eq. of myristate. Fig. S5. Full ITC...

Background Histidine-rich glycoprotein (HRG) regulates coagulation, through its ability to bind and neutralize heparins. HRG associates with zinc ions (Zn2+) to stimulate HRG-heparin complex formation. Under normal conditions the majority of plasma Zn2+ associates with human serum albumin (HSA). However, free fatty acids (FFA) allosterically disrup...

The determination of a 'folding core' can help to provide insight into the structure, flexibility, mobility and dynamics, and hence, ultimately, function of a protein - a central concern of structural biology. Changes in the folding core upon ligand binding are of particular interest because they may be relevant to drug-induced functional changes....

Marine cyanobacteria make a significant contribution to primary production whilst occupying some of the most nutrient poor regions of the world's oceans. The low bioavailability of trace metals can limit the growth of phytoplankton in ocean waters, but only scarce data are available on the requirements of marine microbes for zinc. Recent genome min...

Phospholipase C-η (PLCη) enzymes are a class of phosphatidylinositol 4,5-bisphosphate-hydrolyzing enzymes involved in intracellular signaling. PLCη2 can sense Ca(2+) (stimulated by ∼1 µM free Ca(2+) ) suggesting that it can amplify transient Ca(2+) signals. PLCη enzymes possess an EF-hand domain composed of two EF-loops; a canonical 12-residue loop...

In contrast to molecular chaperones that couple protein folding to ATP hydrolysis, protein disulfide-isomerase (PDI) catalyzes protein folding coupled to formation of disulfide bonds (oxidative folding). However, we do not know how PDI distinguishes folded, partly-folded and unfolded protein substrates. As a model intermediate in an oxidative foldi...

Metal ions play key roles in biology. Many are essential for catalysis, for electron transfer and for the fixation, sensing, and metabolism of gases. Others compete with those essential metal ions or have toxic or pharmacological effects. This book is structured around the periodic table and focuses on the control of metal ions in cells. It address...

Stability constants of the ternary Cu(Arm)(H;PMEC)+ and Cu(Arm)(PMEC) complexes {PMEC2– = dianion of 1-[2-(phosphonomethoxy)ethyl]cytosine, Arm = 2, 2′-bipyridine (Bpy) or 1, 10-phenanthroline (Phen)} were measured by potentiometric pH titrations (aq. sol.; 25 °C; I = 0.1 M, NaNO3) and compared with those of Cu(Arm)(H;PMEA)+ and Cu(Arm)(PMEA) {PMEA...

Background: Serum albumin is the major protein component of blood plasma and is responsible for the circulatory transport of a range of small molecules that include fatty acids, hormones, metal ions and drugs. Studies examining the ligand-binding properties of albumin make up a large proportion of the literature. However, many of these studies do...

More than 30 years have passed since the discovery of the first plant metallothionein in wheat embryos, from which the emergence of a uniquely diverse metallothionein family with a fascinating array of structural nuances and molecular properties has been witnessed. Metallothioneins are not only constitutively expressed, but the production of differ...

Intracellular carbon (C), nitrogen (N) and phosphorus (P) content of marine phytoplankton and bacterioplankton can vary according to cell requirements or physiological acclimation to growth under nutrient limited conditions. Although such variation in macronutrient content is well known for cultured organisms, there is a dearth of data from natural...

Zinc is one of the most important micronutrients for virtually all living organisms, and hence, it is important to understand the molecular mechanisms for its homeostasis. Besides proteins involved in transmembrane transport, both extra- and intracellular zinc-binding proteins play important roles in the respective metabolic networks. Important exa...

The predominant species of the cyanobacterial metalloregulatory protein SmtB as observed by ESI-MS is a dimer with all four zinc binding sites occupied.

It has long been recognized that all organisms have a requirement for a range of metal ions, serving a variety of purposes. The consequences of deficiency for each of these metal ions are grave; however, even essential metal ions are demonstrably toxic at elevated concentrations. Therefore both unicellular and multicellular organisms have developed...

The acidity constants of twofold protonated, antivirally active, acyclic nucleoside phosphonates (ANPs), H(2) (PE)(±) , where PE(2-) =9-[2-(phosphonomethoxy)ethyl]adenine (PMEA(2-) ), 2-amino-9-[2-(phosphonomethoxy)ethyl]purine (PME2AP(2-) ), 2,6-diamino-9-[2-(phosphonomethoxy)ethyl]purine (PMEDAP(2-) ), or 2-amino-6-(dimethylamino)-9-[2-(phosphono...

The biomarker "ischemia-modified albumin" (IMA), measured by the albumin-cobalt-binding assay (ACB assay), is the only FDA-approved biomarker for early diagnosis of myocardial ischemia. On the basis of the hypothesis that high levels of free fatty acids are directly responsible for reduction in cobalt binding by albumin, chemically defined model sy...

Direct polymer conjugation at peptide tyrosine residues is described. In this study Tyr residues of both leucine enkephalin and salmon calcitonin (sCT) were targeted using appropriate diazonium salt-terminated linear monomethoxy poly(ethylene glycol)s (mPEGs) and poly(mPEG) methacrylate prepared by atom transfer radical polymerization. Judicious ch...

Zinc is a recognized essential element for the majority of organisms, and is indispensable for the correct function of hundreds of enzymes and thousands of regulatory proteins. In aquatic photoautotrophs including cyanobacteria, zinc is thought to be required for carbonic anhydrase and alkaline phosphatase, although there is evidence that at least...

Sequence alignment of Fur/Zur-like proteins.

Sequence alignment of members of the COG0523 protein family from the genomes of cyanobacteria.

Phylogenetic tree for Fur/Zur-like proteins extracted from genomes of marine cyanobacteria.