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Components of Nutrition
Published in Christopher Cumo, Ancestral Diets and Nutrition, 2020
Proteins perform crucial functions. For example, insulin, mentioned earlier and having fifty-one amino acids, is the hormone that tells cells to admit glucose.69 In this way, insulin regulates the amounts of glucose inside and outside cells. Insulin also regulates glucose by telling the liver to store excess for release when the sugar becomes scarce in blood. Heme proteins, defined by the presence of iron (Fe), shuttle molecules and electrons throughout the body. Hemoglobin, a component of red blood cells, brings oxygen to cells and removes carbon dioxide for transport to the lungs. Carbon dioxide is a greenhouse gas, though human respiration emits little compared to factories and automobiles. The protein keratin helps form hair and skin. Proteins known as enzymes catalyze the body’s reactions. For example, enzymes pepsin and trypsin aid protein digestion by catalyzing cleavage of amino acid peptide bonds, mentioned earlier. Integral to the immune system, proteins that combat pathogens are known as antibodies. Attention has focused on the protein interferon, which targets viruses.
Liver Diseases
Published in George Feuer, Felix A. de la Iglesia, Molecular Biochemistry of Human Disease, 2020
George Feuer, Felix A. de la Iglesia
The pathway of heme formation has been demonstrated a long time ago.414,510,511 All nitrogen atoms and eight carbon atoms of the heme molecule are derived from glycine, the remaining carbon atoms derive from succinate via the Krebs’ cycle. In the first step, glycine and succinate are combined, and two of the resulting δ-aminolevulinic acid molecules are condensed to give monopyrrole porphobilinogen. The next step is an enzymatic polymerization of four porphobilinogen units leading to the formation of uroporphyrinogen. Subsequently, decarboxylation yields coproporphyrinogen; a side chain modification transforms this compound to protoporphyrinogen IX and finally, the incorporation of ferrous ion gives rise to heme and the addition of a globin leads to hemoglobin459 (Figure 8). The heme molecule is the prostetic group of a variety of hemoproteins such as hemoglobin, myoglobin, cytochromes, catalase, peroxidase, and others.
Heme Oxygenase-1 in Kidney Health and Disease
Published in Shamim I. Ahmad, Handbook of Mitochondrial Dysfunction, 2019
Pu Duann, Elias A. Lianos, Pei-Hui Lin
Heme is an iron-containing porphyrin complex and constitutes the prosthetic group of several hemoproteins with important biological functions. Heme is synthesized in the mitochondria with protoporphyrins supplied from its precursor succinyl-CoA from mitochondria TCA (Kreb) cycle, which then subsequently exported out via the mitochondrial transporter ATP-binding cassette (ABC) B10 after biosynthesis (7). Hemes are most commonly recognized as components of hemoglobin from red blood cells (erythrocytes). Some other examples of hemoproteins include myoglobin (enriched in muscle), catalases, heme peroxidase, cytochromes, and endothelial nitric oxide synthase (eNOS) (8). The redox-active nature of iron makes heme critically involved in modulation of oxidating-reducing activities of hemoproteins which engaged in oxygen transport (hemoglobin) and storage (myoglobin), mitochondrial electron transfer and energy transformation (cytochromes), hydrogen peroxide activation (heme peroxidase) or inactivation (catalases) and nitro oxide synthesis (eNOS) (9). In physiology, significant level of heme could arise from the destruction of aged red blood cells. Because heme also catalyzes the formation of toxic reactive oxygen species (ROS) and free hydroxyl radicals to induce pro-oxidant and cytotoxic effects, level of “free-heme” must be tightly regulated. Disturbed heme metabolism causes mitochondrial decay, oxidative stress, and iron accumulation has been linked to age-related diseases (10).
A novel treatment strategy to prevent Parkinson’s disease: focus on iron regulatory protein 1 (IRP1)
Published in International Journal of Neuroscience, 2023
Thomas M. Berry, Ahmed A. Moustafa
Rotenone inhibits complex I of the electron transport chain by dysregulating iron-sulfur clusters of complex I [84]. Rotenone increases IRP1 and decreases activity of ACO1 [85]. Silencing of IRP1 protects cells from death induced by complex I inhibition [78]. Upon gaining an iron-sulfur cluster due to increases in iron IRP1 becomes aconitase 1 [86]. The goal of supplemental iron would be constant absorption of iron, constant systematic levels of iron and tight iron utilization. Hemoglobin levels could be misleading as to the status of iron-sulfur proteins. Heme is not an iron-sulfur protein. Heme proteins could be normal is PD while iron-sulfur proteins could be dysregulated. In Friedreich’s ataxia iron-sulfur cluster formation is dysregulated, however, hemoglobin levels are normal [87].
Stabilization of Nrf2 leading to HO-1 activation protects against zinc oxide nanoparticles-induced endothelial cell death
Published in Nanotoxicology, 2021
Longbin Zhang, Liyong Zou, Xuejun Jiang, Shuqun Cheng, Jun Zhang, Xia Qin, Zhexue Qin, Chengzhi Chen, Zhen Zou
HO-1 has received considerable attention as a master protective sentinel, that plays a prominent role in different organs and tissues, as well as different pathological scenarios (Otterbein, Foresti, and Motterlini 2016; Satta et al. 2017). As the rate-limiting step in the catabolism of heme into bioactive signaling molecules, the main function of HO-1 is to degrade heme to generate carbon monoxide (CO) and biliverdin and with the simultaneous releasing of iron. These products induce signaling and cytoprotective activities that mitigate apoptosis and inflammation, regulate vasomotor tone, and exhibit antioxidant and immunomodulatory functions. In addition to generation of HO-1-derived products, the role of this enzyme is to counteract oxidative tissue injury triggered by free heme. Large amounts of heme can be released from specific hemoproteins upon oxidative stress, contributing to the amplification of cell and tissue injury (Gozzelino, Jeney, and Soares 2010). Although HO-1 is a crucial arbiter of oxidative stress and inflammatory responses, the precise mechanism of HO-1 in endothelial cell death induced by ZnONPs needs further investigation. Another interesting role of HO-1 may be related to the release of free iron ions upon its profound upregulation, which might trigger nonapoptotic, iron-dependent cell death, called ferroptosis (Dixon et al. 2012; Yang et al. 2014). Our group recently reported that ZnONPs could induce ferroptosis in endothelial cell death (Qin et al. 2021), however whether HO-1 is involved in this process needs further investigation.
In vitro study on the effect of ophiopogonin D on the activity of cytochrome P450 enzymes
Published in Xenobiotica, 2021
Xiaofei Ji, Baodong Ding, Xiaoyou Wu, Fengyi Liu, Fengqi Yang
With the development of Chinese traditional medicine, traditional herbs have been widely used throughout the world. As herb medicine is a mixture containing two or more kinds of herbs in one prescription, the herb-herb interaction and herb-drug interaction have drawn special attention in the past decades. For example, puerarin is widely used in the treatment of cardiovascular diseases and diabetes, and it could inhibit the activity of CYP3A4. There are several cases reporting that puerarin affected the pharmacokinetics of triptolide, edaravone, and astragaloside IV, which resulted from the inhibitory effect of puerarin on the activity of CYP3A4 (Gao et al.2010, Wang et al.2019, Zhang et al.2020). Cytochrome P450 enzymes (CYP450s) are a family of heme proteins that play an important role in the phase-I metabolism of most clinical drugs in the liver and intestine (Zanger and Schwab 2013). The activity of CYP450s directly affects the biotransformation and metabolism of various drugs. Therefore, it is urgent to investigate the effects of herbs on the activity of CYP450s, which can guide the clinical application of herbs in a better way.