Structure of tetragonal crystals of human erythrocyte catalase

Phototherapy for age-related brain diseases: Challenges, successes and future

Brain diseases present a significant obstacle to both global health and economic progress, owing to their elusive pathogenesis and the limited effectiveness of pharmaceutical interventions. Phototherapy has emerged as a promising non-invasive therapeutic modality for addressing age-related brain disorders, including stroke, Alzheimer's disease (AD), and Parkinson's disease (PD), among others. This review examines the recent progressions in phototherapeutic interventions. Firstly, the article elucidates the various wavelengths of visible light that possess the capability to penetrate the skin and skull, as well as the pathways of light stimulation, encompassing the eyes, skin, veins, and skull. Secondly, it deliberates on the molecular mechanisms of visible light on photosensitive proteins, within the context of brain disorders and other molecular pathways of light modulation. Lastly, the practical application of phototherapy in diverse clinical neurological disorders is indicated. Additionally, this review presents novel approaches that combine phototherapy and pharmacological interventions. Moreover, it outlines the limitations of phototherapeutics and proposes innovative strategies to improve the treatment of cerebral disorders.

On the Anti-Cancer Effect of Cold Atmospheric Plasma and the Possible Role of Catalase-Dependent Apoptotic Pathways

Cold atmospheric plasma (CAP) is a promising new agent for (selective) cancer treatment, but the underlying cause of the anti-cancer effect of CAP is not well understood yet. Among different theories and observations, one theory in particular has been postulated in great detail and consists of a very complex network of reactions that are claimed to account for the anti-cancer effect of CAP. Here, the key concept is a reactivation of two specific apoptotic cell signaling pathways through catalase inactivation caused by CAP. Thus, it is postulated that the anti-cancer effect of CAP is due to its ability to inactivate catalase, either directly or indirectly. A theoretical investigation of the proposed theory, especially the role of catalase inactivation, can contribute to the understanding of the underlying cause of the anti-cancer effect of CAP. In the present study, we develop a mathematical model to analyze the proposed catalase-dependent anti-cancer effect of CAP. Our results show that a catalase-dependent reactivation of the two apoptotic pathways of interest is unlikely to contribute to the observed anti-cancer effect of CAP. Thus, we believe that other theories of the underlying cause should be considered and evaluated to gain knowledge about the principles of CAP-induced cancer cell death.

Salivary Redox Biomarkers in the Course of Caries and Periodontal Disease

Caries are a pathological process of extracorporeal nature, characterized by demineralization of inorganic substances as well as proteolysis triggered by acids produced by bacteria present in dental plaque, as a result of metabolism of sugars of both external and internal origin. Periodontal disease, on the other hand, is a multifactorial degenerative disease associated with inflammation, involving a group of tissues that surround the dental cervix and root of the tooth. It is believed that one of the mechanisms in the etiopathogenesis of caries and periodontitis are disorders of local and/or general oxidative stress (OS) parameters. Numerous clinical studies have confirmed the relationship between oxidative stress markers and oral diseases. In most analyzed studies, technical and biological variability was so high that none of the markers so far has proven suitable for routine clinical use. The aim of systematic reviews of the literature is to present the existing studies on OS parameters, mainly concerning the activity of antioxidant enzymes in saliva of patients with caries and periodontitis.

Role of Catalase in Oxidative Stress- and Age-Associated Degenerative Diseases

Reactive species produced in the cell during normal cellular metabolism can chemically react with cellular biomolecules such as nucleic acids, proteins, and lipids, thereby causing their oxidative modifications leading to alterations in their compositions and potential damage to their cellular activities. Fortunately, cells have evolved several antioxidant defense mechanisms (as metabolites, vitamins, and enzymes) to neutralize or mitigate the harmful effect of reactive species and/or their byproducts. Any perturbation in the balance in the level of antioxidants and the reactive species results in a physiological condition called “oxidative stress.” A catalase is one of the crucial antioxidant enzymes that mitigates oxidative stress to a considerable extent by destroying cellular hydrogen peroxide to produce water and oxygen. Deficiency or malfunction of catalase is postulated to be related to the pathogenesis of many age-associated degenerative diseases like diabetes mellitus, hypertension, anemia, vitiligo, Alzheimer's disease, Parkinson's disease, bipolar disorder, cancer, and schizophrenia. Therefore, efforts are being undertaken in many laboratories to explore its use as a potential drug for the treatment of such diseases. This paper describes the direct and indirect involvement of deficiency and/or modification of catalase in the pathogenesis of some important diseases such as diabetes mellitus, Alzheimer's disease, Parkinson's disease, vitiligo, and acatalasemia. Details on the efforts exploring the potential treatment of these diseases using a catalase as a protein therapeutic agent have also been described.

Trivalent Phosphorus and Phosphines as Components of Biochemistry in Anoxic Environments

Phosphorus is an essential element for all life on Earth, yet trivalent phosphorus (e.g., in phosphines) appears to be almost completely absent from biology. Instead phosphorus is utilized by life almost exclusively as phosphate, apart from a small contingent of other pentavalent phosphorus compounds containing structurally similar chemical groups. In this work, we address four previously stated arguments as to why life does not explore trivalent phosphorus: (1) precedent (lack of confirmed instances of trivalent phosphorus in biochemicals suggests that life does not have the means to exploit this chemistry), (2) thermodynamic limitations (synthesizing trivalent phosphorus compounds is too energetically costly), (3) stability (phosphines are too reactive and readily oxidize in an oxygen (O₂)-rich atmosphere), and (4) toxicity (the trivalent phosphorus compounds are broadly toxic). We argue that the first two of these arguments are invalid, and the third and fourth arguments only apply to the O₂-rich environment of modern Earth. Specifically, both the reactivity and toxicity of phosphines are specific to aerobic life and strictly dependent on O₂-rich environment. We postulate that anaerobic life persisting in anoxic (O₂-free) environments may exploit trivalent phosphorus chemistry much more extensively. We review the production of trivalent phosphorus compounds by anaerobic organisms, including phosphine gas and an alkyl phosphine, phospholane. We suggest that the failure to find more such compounds in modern terrestrial life may be a result of the strong bias of the search for natural products toward aerobic organisms. We postulate that a more thorough identification of metabolites of the anaerobic biosphere could reveal many more trivalent phosphorus compounds. We conclude with a discussion of the implications of our work for the origin and early evolution of life, and suggest that trivalent phosphorus compounds could be valuable markers for both extraterrestrial life and the Shadow Biosphere on Earth.

Expression and Enzyme Activity of Catalase in Chilo suppressalis (Lepidoptera: Crambidae) Is Responsive to Environmental Stresses

Catalase (CAT) is an important antioxidant enzyme that protects organisms against oxidative stresses by eliminating hydrogen peroxide. In this study, we cloned and characterized a full-length cDNA of CAT from Chilo suppressalis (CsCAT) and examined the influence of environmental stresses on CsCAT expression and enzyme activity. The cDNA contains a 1659-bp open reading frame encoding a polypeptide of 553 amino acids most closely related (90.14%) to Papilio polytes catalases. The CsCAT was expressed in all developmental stages with the highest expression in the fat body, and the CsCAT enzyme activity closely mirrored its observed mRNA expression patterns. The CsCAT mRNA was up-regulated when the larvae were exposed to high temperature (≥30 °C), insecticides (abamectin and chlorantraniliprole), chemicals (H2O2, CHP, CdCl2, and CuSO4), and a dead-end trap plant (vetiver grass), and the CsCAT enzyme activity again mirrored the observed CsCAT expression patterns. These results suggest that up-regulation of CsCAT may enhance the defense response of C. suppressalis by weakening the effects of environmental stresses, and provide insight into the role of CsCAT during development of C. suppressalis.

Targeting cellular antioxidant enzymes for treating atherosclerotic vascular disease

Atherosclerotic vascular dysfunction is a chronic inflammatory process that spreads from the fatty streak and foam cells through lesion progression. Therefore, its early diagnosis and prevention is unfeasible. Reactive oxygen species (ROS) play important roles in the pathogenesis of atherosclerotic vascular disease. Intracellular redox status is tightly regulated by oxidant and antioxidant systems. Imbalance in these systems causes oxidative or reductive stress which triggers cellular damage or aberrant signaling, and leads to dysregulation. Paradoxically, large clinical trials have shown that non-specific ROS scavenging by antioxidant vitamins is ineffective or sometimes harmful. ROS production can be locally regulated by cellular antioxidant enzymes, such as superoxide dismutases, catalase, glutathione peroxidases and peroxiredoxins. Therapeutic approach targeting these antioxidant enzymes might prove beneficial for prevention of ROS-related atherosclerotic vascular disease. Conversely, the development of specific antioxidant enzyme-mimetics could contribute to the clinical effectiveness.

Molecular characterization of a catalase from Hydra vulgaris

Catalase, an antioxidant and hydroperoxidase enzyme protects the cellular environment from harmful effects of hydrogen peroxide by facilitating its degradation to oxygen and water. Molecular information on a cnidarian catalase and/or peroxidase is, however, limited. In this work an apparent full length cDNA sequence coding for a catalase (HvCatalase) was isolated from Hydra vulgaris using 3'- and 5'- (RLM) RACE approaches. The 1859 bp HvCatalase cDNA included an open reading frame of 1518 bp encoding a putative protein of 505 amino acids with a predicted molecular mass of 57.44 kDa. The deduced amino acid sequence of HvCatalase contained several highly conserved motifs including the heme-ligand signature sequence RLFSYGDTH and the active site signature FXRERIPERVVHAKGXGA. A comparative analysis showed the presence of conserved catalytic amino acids [His(71), Asn(145), and Tyr(354)] in HvCatalase as well. Homology modeling indicated the presence of the conserved features of mammalian catalase fold. Hydrae exposed to thermal, starvation, metal and oxidative stress responded by regulating its catalase mRNA transcription. These results indicated that the HvCatalase gene is involved in the cellular stress response and (anti)oxidative processes triggered by stressor and contaminant exposure.

Human catalase: looking for complete identity

Catalases are well studied enzymes that play critical roles in protecting cells against the toxic effects of hydrogen peroxide. The ubiquity of the enzyme and the availability of substrates made heme catalases the focus of many biochemical and molecular biology studies over 100 years. In human, this has been implicated in various physiological and pathological conditions. Advancement in proteomics revealed many of novel and previously unknown features of this mysterious enzyme, but some functional aspects are yet to be explained. Along with discussion on future research area, this mini-review compile the information available on the structure, function and mechanism of action of human catalase.

Maternally transmitted milk containing recombinant human catalase provides protection against oxidation for mouse offspring during lactation

Catalase plays an important role in protecting organisms against oxidative damage caused by reactive oxygen species (ROS) by degrading surplus hydrogen peroxide. Addition of exogenous catalase can alleviate injuries caused by ROS. Thus, production of human catalase through genetic engineering will meet the increasing therapeutic demand for this enzyme. In this study, we successfully expressed the recombinant gene in mouse mammary gland, and biologically active human catalase was secreted into the milk of the transgenic mice. The peroxisomal targeting sequence (PTS) within the catalase gene had no significant negative effect on the secretion of the recombinant protein. Intake of the transgenic milk by the pups was found to decrease lipid peroxidation, increase the total superoxide dismutase (T-SOD) activity in the brain, and enhance the total antioxidative capacity (T-AOC) of brain, liver, and serum. To our knowledge, this is the first example of efficient production of biologically active human catalase in the milk of transgenic animals. Our study suggests that scaled-up production in transgenic farm animals would yield sufficient human catalase for biomedical research and clinical therapies.

Unusual Cys-Tyr covalent bond in a large catalase

Catalase-1, one of four catalase activities of Neurospora crassa, is associated with non-growing cells and accumulates in asexual spores. It is a large, tetrameric, highly efficient, and durable enzyme that is active even at molar concentrations of hydrogen peroxide. Catalase-1 is oxidized at the heme by singlet oxygen without significant effects on enzyme activity. Here we present the crystal structure of catalase-1 at 1.75A resolution. Compared to structures of other catalases of the large class, the main differences were found at the carboxy-terminal domain. The heme group is rotated 180 degrees around the alpha-gamma-meso carbon axis with respect to clade 3 small catalases. There is no co-ordination bond of the ferric ion at the heme distal side in catalase-1. The catalase-1 structure exhibited partial oxidation of heme b to heme d. Singlet oxygen, produced catalytically or by photosensitization, may hydroxylate C5 and C6 of pyrrole ring III with a subsequent formation of a gamma-spirolactone in C6. The modification site in catalases depends on the way dioxygen exits the protein: mainly through the central channel or the main channel in large and small catalases, respectively. The catalase-1 structure revealed an unusual covalent bond between a cysteine sulphur atom and the essential tyrosine residue of the proximal side of the active site. A peptide with the predicted theoretical mass of the two bound tryptic peptides was detected by mass spectrometry. A mechanism for the Cys-Tyr covalent bond formation is proposed. The tyrosine bound to the cysteine residue would be less prone to donate electrons to compound I to form compound II, explaining catalase-1 resistance to substrate inhibition and inactivation. An apparent constriction of the main channel at Ser198 lead us to propose a gate that opens the narrow part of the channel when there is sufficient hydrogen peroxide in the small cavity before the gate. This mechanism would explain the increase in catalytic velocity as the hydrogen peroxide concentration rises.

Identification of amyloid-beta binding sites using an antisense peptide approach

The amyloid-beta (A beta) peptide is a cytotoxic peptide implicated in the pathology of Alzheimer's disease (AD). Catalase and the endoplasmic reticulum A beta binding dehydrogenase (ERAB) are both inhibited by characterized fragments of the A beta peptide. In order to target such proteins it is essential to determine which components of these enzymes interact with A beta. This study reports the use of antisense peptide methodology to identify specific A beta-binding domains. Synthetic peptides corresponding to the regions of catalase and ERAB identified showed specific binding to A beta and also prevented A beta cytotoxicity. Antisense peptide methodology has identified A beta recognition sequences and may also be applied to the identification of novel A beta protein interactions to identify targets for use in the treatment of AD.