Biomolecules hemoglobin

Application to biomolecules started as early as the mid-fifties with single-crystal EPR studies on hemoglobin (Bennett et al. 1955), but in hindsight it now appears that... 

The 5-iodoacetamido derivative of fluorescein (5-IAF) has been used to label numerous proteins and other biomolecules, including actin (Plank and Ware, 1987), myosin (Aguirre et al., 1986), troponin (Greene, 1986), hemoglobin (Hirsch et al., 1986), and sulfhydryl-containing proteins separated by SDS electrophoresis (Gorman, 1984). 

Several enzymes have been immobilized in sol-gel matrices effectively and employed in diverse applications. Urease, catalase, and adenylic acid deaminase were first encapsulated in sol-gel matrices [72], The encapsulated urease and catalase retained partial activity but adenylic acid deaminase completely lost its activity. After three decades considerable attention has been paid again towards the bioencapsulation using sol-gel glasses. Braun et al. [73] successfully encapsulated alkaline phosphatase in silica gel, which retained its activity up to 2 months (30% of initial) with improved thermal stability. Further Shtelzer et al. [58] sequestered trypsin within a binary sol-gel-derived composite using TEOS and PEG. Ellerby et al. [74] entrapped other proteins such as cytochrome c and Mb in TEOS sol-gel. Later several proteins such as Mb [8], hemoglobin (Hb) [56], cyt c [55, 75], bacteriorhodopsin (bR) [76], lactate oxidase [77], alkaline phosphatase (AP) [78], GOD [51], HRP [79], urease [80], superoxide dismutase [8], tyrosinase [81], acetylcholinesterase [82], etc. have been immobilized into different sol-gel matrices. Hitherto some reports have described the various aspects of sol-gel entrapped biomolecules such as conformation [50, 60], dynamics [12, 83], accessibility [46], reaction kinetics [50, 54], activity [7, 84], and stability [1, 80],... 

Computer-generated model of the quaternary structure of hemoglobin, a protein consisting of four interlinked polypeptide chains, each shown in a different color. Computers are important tools for the study of biomolecules, as they help scientists visualize complex three-dimensional structures. 

The role of the transition elements in living systems is equally important. Iron is present in biomolecules such as hemoglobin, which transports oxygen from our lungs to other parts of the body. Cobalt is an essential component of vitamin B12. Nickel, copper, and zinc are vital constituents of many enzymes, the large protein molecules that catalyze biochemical reactions. 

A particularly useful kind of biomarker used with increasing frequency during recent years consists of adducts of xenobiotics or their metabolites to biomolecules. A particularly straightforward example of such an adduct measured for many years as evidence of exposure is carboxyhe-moglobin, COHb, produced when inhaled carbon monoxide adds to blood hemoglobin, Hb ... 

One of the most significant common aspects of the chemistry of NO and peroxynitrite is their ability to react in a unique manner with the metal centers of numerous proteins, in particular hemoproteins [10]. We have used myoglobin (Mb) and hemoglobin (Hb) to investigate the diverse reactions that these simple inorganic biomolecules can undergo with different oxidation states of hemoproteins. Mutated forms of Mb and Hb are available [12, 13], and a large number of transition metals ions other than Fe ions have been successfully incorporated in these... 

Even though in vitro experiments necessarily remove biomolecules from the cellular environment, the structures and dynamics of individual macromolecules provide insights to their biological functions. For example, structural studies have revealed that the protein hemoglobin is made up of four interacting subunits, two a subunits and two ft subunits. Furthermore, each subunit has two distinct conformational states, called the R state and the T state, and the energy of interaction between two neighboring subunits in different states is different from that of two subunits in the same state. This phenomenon is the structural basis of the observed allosteric... 

Hemoglobin dramatically demonstrates how sensitive the function of a biomolecule is to its structure. In certain people, in the synthesis of the proteins needed for hemoglobin, an improper amino acid is inserted into the protein in two places. This may not seem very serious, since there are several hundred amino acids present. However, because the incorrectly inserted amino acid has a nonpolar substituent instead of the polar one found on the proper amino acid, the hemoglobin drastically changes its shape. The red blood cells are then sickle-shaped rather than disk-shaped, as shown in Fig. 20.37. The misshapen cells can aggregate, causing clogging of tiny capillaries. This condition, known as sickle cell anemia, is the subject of intense research. 

Hemoglobin a biomolecule composed of four myoglobinlike units (proteins plus heme) that can bind and transport four oxygen molecules in the blood. (20.8)... 

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