Biochemistry of Copper Site Assembly in Heme-Copper Oxidases: A Theme with Variations

Exploring antioxidant strategies in the pathogenesis of ALS

The central nervous system is essential for maintaining homeostasis and controlling the body's physiological functions. However, its biochemical characteristics make it highly vulnerable to oxidative damage, which is a common factor in neurodegenerative diseases like amyotrophic lateral sclerosis (ALS). ALS is a leading cause of motor neuron disease, characterized by a rapidly progressing and incurable condition. ALS often results in death from respiratory failure within 3-5 years from the onset of the first symptoms, underscoring the urgent need to address this medical challenge. The aim of this study is to present available data supporting the role of oxidative stress in the mechanisms underlying ALS and to discuss potential antioxidant therapies currently in development. These therapies aim to improve the quality of life and life expectancy for patients affected by this devastating disease.

Serum copper concentration reflect inflammatory activation in the complex coronary artery disease - A pilot study

INTRODUCTION

Coronary artery disease possess inflammatory background related to enzymatic processes with trace elements involvements as co-factors. The aim of the study was to compare serum, urine and salivary copper, magnesium, calcium and zinc levels with inflammatory indices obtained from the whole blood count in patients with complex coronary artery disease.

MATERIAL AND METHOD

Fifty-two (42(81 %) males, 10 (19 %) females) consecutive patients (mean (SD) age 68 (9) years with symptomatic complex coronary artery disease were enrolled into prospective single center study in 2021. Serum, saliva and urine samples were collected at the day of admission for trace elements concentration (copper, zinc, magnesium, calcium) and compared with inflammatory indexes obtained from preoperative and perioperative period.

RESULTS

Multivariable regression analysis revealed relation between the copper serum concentration and neutrophil to lymphocyte ratio (NLR) and systemic inflammatory index (SII).

CONCLUSION

Serum copper concentration interplay with preoperative inflammatory activation in complex coronary disease measured by NLR and SII. The copper serum concentration possesses the strongest relation to preoperative inflammatory activation in patients reffered for off-pump coronary artery bypass grafting.

Diversity of Cytochrome c Oxidase Assembly Proteins in Bacteria

Cytochrome c oxidase in animals, plants and many aerobic bacteria functions as the terminal enzyme of the respiratory chain where it reduces molecular oxygen to form water in a reaction coupled to energy conservation. The three-subunit core of the enzyme is conserved, whereas several proteins identified to function in the biosynthesis of the common family A1 cytochrome c oxidase show diversity in bacteria. Using the model organisms Bacillus subtilis, Corynebacterium glutamicum, Paracoccus denitrificans, and Rhodobacter sphaeroides, the present review focuses on proteins for assembly of the heme a, heme a₃, Cu_B, and Cu_A metal centers. The known biosynthesis proteins are, in most cases, discovered through the analysis of mutants. All proteins directly involved in cytochrome c oxidase assembly have likely not been identified in any organism. Limitations in the use of mutants to identify and functionally analyze biosynthesis proteins are discussed in the review. Comparative biochemistry helps to determine the role of assembly factors. This information can, for example, explain the cause of some human mitochondrion-based diseases and be used to find targets for new antimicrobial drugs. It also provides information regarding the evolution of aerobic bacteria.

Experimental and Theoretical DFT Study of Cu(I)/N,N-Disubstituted-N'-acylthioureato Anticancer Complexes: Actin Cytoskeleton and Induction of Death by Apoptosis in Triple-Negative Breast Tumor Cells

Six complexes with the general formula [Cu(acylthioureato)(PPh3)2] were synthesized and characterized using spectroscopic techniques (IR, UV/visible, and 1D and 2D NMR), mass spectrometry, elemental analysis, and X-ray diffraction. Interpretation of the in vitro cytotoxicity data of Cu(I) complexes took into account their stability in cell culture medium. DFT calculations showed that NMR properties, such as the shielding of carbon atoms, are affected by relativistic effects, supported by the ZORA Hamiltonian in the theoretical calculations. Additionally, the calculation of the energies of the frontier molecular orbitals predicted that the structural changes of the acylthiourea ligands did not cause marked changes in the reactivity descriptors. All complexes were cytotoxic to the evaluated tumor cell lines [MDA-MB-231 (triple-negative breast cancer, TNBC), MCF-7 (breast cancer), and A549 (lung cancer)]. In the MDA-MB-231 cell line, complex 1 significantly altered the cytoskeleton of the cells, reducing the density and promoting the condensation of F-actin filaments. In addition, the compound caused an increase in the percentage of cells in the fragmented DNA region (sub-G0) and induced cell death via the apoptotic pathway starting at the IC50 concentration. Taken together, the results show that complex 1 has cytotoxic and apoptotic effects on TNBC cells, which is a cell line originating from an aggressive, difficult-to-treat breast cancer.

Using a chemical genetic screen to enhance our understanding of the antimicrobial properties of copper

The competitive toxic and stress inducing nature of copper necessitates systems that sequester and export this metal from the cytoplasm of bacterial cells. Several predicted mechanisms of toxicity include the production of reactive oxygen species, thiol depletion, DNA and iron-sulfur cluster disruption. Accompanying these mechanisms include pathways of homeostasis such as chelation, oxidation, and transport. Still, the mechanisms of copper resistance and sensitivity are not fully understood. Furthermore, studies fail to recognize that the response to copper is likely a result of numerous mechanisms, as in the case for homeostasis, in which proteins and enzymes work as a collective to maintain appropriate copper concentrations. In this study we used the Keio collection, an array of 3985 Escherichia coli mutants, each with a deleted non-essential gene, to gain a better understanding of prolonged copper exposure. In short, we recovered two copper homeostatic gene and genes involved in transporting and assembling to be involved in mediating prolonged copper stress under the conditions assessed. The gene coding for the protein TolC was uncovered as a sensitive hit and we demonstrated that tolC, an outer membrane efflux channel, is key in mitigating copper sensitivity. Additionally, the activity of tRNA processing was enriched and the deletion of several proteins involved in import generated copper tolerance. Lastly, key genes belonging to central carbon metabolism and nicotinamide adenine dinucleotide biosynthesis were uncovered as tolerant hits. Overall, this study shows that copper sensitivity and tolerance are a result of numerous mechanisms acting in combination within the cell.

Effect of Cadmium and Copper Exposure on Growth, Physio-Chemicals and Medicinal Properties of Cajanus cajan L. (Pigeon Pea)

Soil contamination with heavy metals is an emerging concern in the modern era, affecting all forms of life. Pigeon pea is a multi-use shrub with medicinal and nutritional values. On the basis of a randomized complete design, we investigated in the current project the combined cadmium (Cd) and copper (Cu) effect on plant growth and physio-chemical/medicinal properties of pigeon pea. Three-week-old seedlings were grown in combined Cd and Cu amended soil with increasing metal concentrations (control, 20 + 30 mg/kg, 40 + 60 mg/kg, and 60 + 90 mg/kg) for three months. At high-dose metal cumulative stress (60 + 90 mg/kg), plant shoot and root growth in terms of plant height as well as fresh and dry weight were significantly inhibited in association with decreased photosynthetic attributes (chlorophyll a and b contents, net photosynthesis, transpiration rate, stomatal conductance, intercellular CO₂ concentrations) and diminished nutrient contents. Cd and Cu at high amounts inflicted oxidative stresses as assessed in elevated lipid peroxidation (MDA), hydrogen peroxide (H₂O₂), and electrolyte leakage contents. Antioxidant enzyme activities, namely, those of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and glutathione peroxidase (GPX), were enhanced, along with proline content with increasing metal quantity. Phenolics and flavonoids exhibited a diverse response regarding metal concentration, and their biosynthesis was significantly suppressed at high Cd and Cu cumulative stress. The reduction in secondary metabolites may account for declined medicinal properties of pigeon pea as appraised in reduced antibacterial, 2, 2-diphenyl-1-picrylhydrazyl (DPPH), and ferric-reducing antioxidant potential (FRAP) activities. Our results clearly demonstrate that the exposure of pigeon pea to Cd- and Cu-contaminated soil might affect consumers due to the presence of metals and the negligible efficacy of the herbal products.

Rutin ameliorates copper sulfate-induced brain damage via antioxidative and anti-inflammatory activities in rats

Excessive exposure to Copper (Cu) may result in Cu toxicity and adversely affect health outcomes. We investigated the protective role of rutin on Cu-induced brain damage. Experimental rats were treated as follows: group I: control; group II: Cu-sulfate: 200 mg/kg; group III: Cu-sulfate, and rutin 100 mg/kg; and group IV: rutin 100 mg/kg, for 7 weeks. Cu only treatment significantly decreased body weight gain, while rutin cotreatment reversed this decrease. Cu treatment increased malondialdehyde, nitric oxide level, and myeloperoxidase activity and decreased superoxide dismutase and catalase activities in rat brain. Immunohistochemistry showed that COX-2, iNOS, and Bcl-2 proteins were strongly expressed, while Bax was mildly expressed in the brain of Cu-treated rats. Furthermore, brain histology revealed degenerated neurons, and perforated laminae of cerebral cortex in the Cu-only treated rats. Interestingly, coadministration of Cu and rutin reduced the observed histological alteration, improved inflammatory and antioxidant biomarkers, thereby protecting against Cu-induced brain damage via antioxidative and anti-inflammatory mechanisms.

Iron and Chelation in Biochemistry and Medicine: New Approaches to Controlling Iron Metabolism and Treating Related Diseases

Iron is essential for all living organisms. Many iron-containing proteins and metabolic pathways play a key role in almost all cellular and physiological functions. The diversity of the activity and function of iron and its associated pathologies is based on bond formation with adjacent ligands and the overall structure of the iron complex in proteins or with other biomolecules. The control of the metabolic pathways of iron absorption, utilization, recycling and excretion by iron-containing proteins ensures normal biologic and physiological activity. Abnormalities in iron-containing proteins, iron metabolic pathways and also other associated processes can lead to an array of diseases. These include iron deficiency, which affects more than a quarter of the world's population; hemoglobinopathies, which are the most common of the genetic disorders and idiopathic hemochromatosis. Iron is the most common catalyst of free radical production and oxidative stress which are implicated in tissue damage in most pathologic conditions, cancer initiation and progression, neurodegeneration and many other diseases. The interaction of iron and iron-containing proteins with dietary and xenobiotic molecules, including drugs, may affect iron metabolic and disease processes. Deferiprone, deferoxamine, deferasirox and other chelating drugs can offer therapeutic solutions for most diseases associated with iron metabolism including iron overload and deficiency, neurodegeneration and cancer, the detoxification of xenobiotic metals and most diseases associated with free radical pathology.

Biochemical pathway for the biosynthesis of the CuA center in bacterial cytochrome c oxidase

The di-copper center Cu_A is an essential metal cofactor in cytochrome oxidase (Cox) of mitochondria and many prokaryotes, mediating one-electron transfer from cytochrome c to the site for oxygen reduction. Cu_A is located in subunit II (CoxB) of Cox and protrudes into the periplasm of Gram-negative bacteria or the mitochondrial intermembrane space. How the two copper ions are brought together to build CoxB·Cu_A is the subject of this review. It had been known that the reductase TlpA and the metallochaperones ScoI and PcuC are required for Cu_A formation in bacteria, but the mechanism of copper transfer has emerged only recently for the Bradyrhizobium diazoefficiens system. It consists of the following steps: (a) TlpA keeps the active site cysteine pair of CoxB in its dithiol state as a prerequisite for metal insertion; (b) ScoI·Cu²⁺ rapidly forms a transient complex with apo-CoxB; (c) PcuC, loaded with Cu¹⁺ and Cu²⁺ , dissociates this complex to CoxB·Cu²⁺ , and a second PcuC·Cu¹⁺ ·Cu²⁺ transfers Cu¹⁺ to CoxB·Cu²⁺ , yielding mature CoxB·Cu_A . Variants of this pathway might exist in other bacteria or mitochondria.