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Arsenals of Pharmacotherapeutically Active Proteins and Peptides: Old Wine in a New Bottle
Published in Debarshi Kar Mahapatra, Swati Gokul Talele, Tatiana G. Volova, A. K. Haghi, Biologically Active Natural Products, 2020
Hemoglobin is a heme protein involved in the transport of oxygen. It comprises of iron ion, porphyrin ring (heme complex), and globin (protein). The hemoglobin molecule is tetramer of two α and two β subunits. The α-subunit is 141 amino acids in length while the β subunit is 146 amino acids in length. The α-subunit has Val-Leu sequence at N-terminal and β subunit has Val-His-Leu sequence at N-terminal [69]. The α-subunit possesses seven α-helices (designated as A-G) and the β subunit comprises eight α-helices (designated as A-H). The subunits are compacted to form a globe-shaped structure with space within each subunit for the heme complex. The heme complex (iron-protoporphyrin IX) consists of porphyrin ring and iron ion, Fe2+ as shown in Figure 2.28.
Cell Biology for Bioprocessing
Published in Wei-Shou Hu, Cell Culture Bioprocess Engineering, 2020
In addition to their role in energy metabolism, mitochondria also play a key role in the regulation of apoptosis. Some pro-apoptotic proteins are sequestered in the space between the outer and inner membranes of mitochondria. Cytochrome C, a hemeprotein that is an important component of the cytochrome C complex in the electron transport chain, is associated with the inner membrane of mitochondria. The release of cytochrome C and those pro-apoptotic proteins in stressed cells initiates the intrinsic pathway of apoptosis (Figure 2.22). The cytochrome C released into the cytoplasm proceeds to form a complex with APF1, pro-caspase 9, and dATP, known collectively as the apoptosome. In the apoptosome, the inactive pro-caspase 9 becomes activated and subsequently activates downstream caspases.
Structures
Published in Thomas M. Nordlund, Peter M. Hoffmann, Quantitative Understanding of Biosystems, 2019
Thomas M. Nordlund, Peter M. Hoffmann
Heme is a prosthetic group, a group at the center of activity, of proteins and enzymes (see Figure 5.8). The molecular mass of heme is between 600 and 700 Da, depending on the particular heme. Proteins with heme prosthetic groups are called hemoproteins or heme proteins. Hemoproteins have biological functions including the transport of O2, chemical catalysis, diatomic gas detection, and electron transfer. The heme iron serves as a source or sink of electrons during electron transfer or redox (oxidation–reduction) chemistry, and as a binding site for molecules such as O2 (good) and CO (not good). Hemoproteins achieve their variety of functions by modifying the environment of the heme, sometimes forming covalent bonds to groups on the edge of the heme or providing a different charge or dielectric environment. We now note a few obvious features of the heme group, leaving the details for later.
A novel amperometric biosensor for rapid detection of ethanol utilizing gold nanoparticles and enzyme coupled PVC reaction cell
Published in Environmental Technology, 2021
Vinita Hooda, Anjum Gahlaut, Vikas Hooda
Over the past few years, the use of nanoparticles in the development of next-generation sensors has been augmented credited to their exceptional electrical, optical, thermal and mechanical properties which help to ameliorate vital performance indexes – selectivity, sensitivity, repeatability and stability. c-MWCNTs display high electroactive surface owing to its excellent thermal and electrical conductivity which leads to fast exchange of electrons between the enzyme and the electrode [22]. Carbon nanotubes and gold nanoparticles have high surface to volume ratio and strong electrical properties which facilitate the capacity of enzyme loading onto electron surface and amplify the signal. Nafion has also attracted much attention in biosensor applications due to its excellent thermal stability, biocompatibility, antifouling property as well as high mechanical strength. Additionally, nafion can effectively solubilize CNTs which help in the fabrication of biosensors having both the efficient electrocatalytic property of CNTs and antifouling action of nafion films [23,24]. Chitosan (a biopolymer) has also been extensively used in biosensor fabrication owing to their hydrophilic nature, easy availability, high permeability, easy to modify, high mechanical strength, film-forming ability, low cost and non-toxicity [25]. To circumvent the use of additional redox mediators, the application of DET exhibiting hemoproteins and other enzymes which have the ability to transfer electrons directly towards the electrode opens new opportunities in the designing of biosensors and biofuel cells [26]. Hemoproteins are a huge class of proteins which have iron ions containing heme groups demonstrating unique oxidation/reduction properties suitable for DET. The majority of enzymes exhibiting DET towards the electrode have recognized intrinsic electron transfer pathways partly depending upon the action of metal-coordinated complexes including heme-c, copper and iron-sulphur. Peroxidase was the first heme-c containing enzyme which was reported to transfer electrons efficiently to carbon [27–30] and gold-based electrode [31]. Several DET-able heme-c based peroxidases including horseradish peroxidase [32–34], microperoxidase-11 (MP-11) [35] and microperoxidase-8 [28] have been applied in the field of biosensorics and bioelectronics. In healthcare sector, colossal potential of nanoparticles, DET-able enzymes and CNTs has enhanced scientific fervor towards the development of biosensors for marketable accomplishments. In the future, the utilization of biofuel cells as energy supplying source in the fabrication of biosensors will be promising [28].