Proteins, Lipids, and Nucleic Acids

Proteins, Lipids, and Nucleic Acids in Cell Structure and Functions Albert Claude... 

Methods for Determining Biomarkers of Exposure and Effect. Covalent adducts between reactive carbon tetrachloride metabolites (e.g., the trichloromethyl radical) and cellular proteins, lipids and nucleic acids are known to occur, but at present these can only be measured using radiolabeled carbon tetrachloride. Development of immunological or other methods to detect such adducts in humans exposed to carbon tetrachloride could be of value in estimating past exposures to carbon tetrachloride. 

The biomolecules that constitute matter in living organisms are often polymers with molecular masses of the order of a million or even larger. As discussed later in this chapter, these biomolecules may be divided into the categories of carbohydrates, proteins, lipids, and nucleic acids. Proteins and nucleic acids consist of macromolecules, lipids are usually relatively small molecules, and carbohydrates range from relatively small sugar molecules to high-molecular-mass macromolecules, such as those in cellulose. 

RNA secondary structure plays a role in the regulation of iron metabolism in eukaryotes. Iron is an essential nutrient, required for the synthesis of hemoglobin, cytochromes, and many other proteins. However, excess iron can be quite harmful because, untamed by a suitable protein environment, iron can initiate a range of free-radical reactions that damage proteins, lipids, and nucleic acids. Animals have evolved sophisticated systems for the accumulation of iron in times of scarcity and for the safe storage of excess iron for later use. Key proteins include transferrin, a transport protein that carries iron in the serum, transferrin receptor, a membrane protein that binds iron-loaded transferrin and initiates its entry into cells, and ferritin, an impressively efficient iron-storage protein found primarily in the liver and kidneys. Twenty-four ferritin polypeptides form a nearly spherical shell that encloses as many as 2400 iron atoms, a ratio of one iron atom per amino acid (Figure 31.37). 

The major types of molecules found in organisms are water, carbohydrates, proteins, lipids, and nucleic acids. 

Carcinogens can be divided into two general types those that act directly and those that act indirectly. Direct-acting carcinogens are those that interact with cellular constituents such as protein, lipids, and nucleic acids. There are relatively few direct-acting carcinogens (e.g., bis(chloromethyl)ether, ethylene oxide, and nitrogen mustard). 

This section covers the investigation of simple amino acids, proteins, lipids and nucleic acids. In particular, in proteins, molecular dynamics is an important link between molecular structure and function." " Among the hrst experimental approaches of... 

The viscous and gel-forming properties of mucus secretions are derived from mucin glycoprotein constituents (5%) they also contains protein, lipid and nucleic acid, much of it derived from dislodged epithelial cells and bacteria [199]. These constituents have been shown to enhance the viscous properties of mucins in vitro [200, 201], and such interactions may be significant towards determining mucus gel properties in vivo. 

Recall that oxidative stress results from reactive oxygen or nitrogen species that are not fully neutralized by anti-oxidants (see Chapter 24). The increase in reactive oxygen and nitrogen species results in protein, lipid, and nucleic acid modifications. Many neurodegenerative diseases, such as Alzheimer disease, Parkinson disease, and Lou Gehrig disease, have in common increased oxidative stress. 

Metabolism refers to the dynamic changes of the molecules within a cell, especially those small molecules used as sources of energy and as precursors for the synthesis of proteins, lipids, and nucleic acids. These reactions occur in the steady state rather than all at once. Steady state refers to dynamic equilibrium, or homeostasis, where the individual molecules change but the rate at which they are made equals the rate at which they are destroyed. Concentrations of individual molecules in metabolic reactions are therefore kept relatively... 

Carbohydrates are ubiquitous. Every organism contains some carbohydrate. Carbohydrates can range from a simple monosaccharide to a large complex polysaccharide. Polysaccharides in combination with proteins, lipids, and nucleic acids play an important role in many plant and animal metabolic systems. Carbohydrates have many roles in food systems, where they function to provide flavor, structure, and texture to food and nutritional benefits to the consumer. This chapter attempts to address the role of common plant monosaccharides, oligosaccharides, and polysaccharides as ingredients in food systems by discussing their occurrence in plants, commercial processing, functionality, food uses, and healthful properties. 

Several aspects of neutron scattering studies are particularly elegant and unique in terms of the contrast variation method to examine internal structures as well as the external morphology. Thus the protein positions within the 30S ribosomal subunit can be determined by triangulation of deuterated subunits [489,490] the shell-like spherical structures of protein, lipid and nucleic acid within viruses [546,555,566] and lipoproteins can be analysed the distinct disposition of carbohydrates within glycoproteins [197,198,214], membranes within membrane proteins [39], or proteins within protein-nucleic acid complexes [385,387,392] can be elucidated. Likewise X-ray scattering has been of value in protein-lipid systems since these two components can be readily distinguished from one another [75,76]... 

ArC = —2331.29 kJ for the reaction as written (aTable 2.5 and 2.7 calculation). Ofcour.se. enzymes must evolve that couple this exeigonic redox reaction to the production of ATP, which would then be available for caihohydiate, protein, lipid, and nucleic acid synthesis. 

On-chip cell lysis is a crucial component of integrated micro total analysis systems (pTAS). In order to perform biochemical analysis of intercellular molecules (i.e., proteins, lipids, and nucleic acids), the cells at first have to be disrupted, releasing the biomolecules from inside... 

The mapping of a single cell from a wheat cross section (aleurine cell from a row of cells between the endosperm and seed coat) was achieved as early as 1993 [263]. With the use of a synchrotron source of IR radiation, maps of an aleurine cell and a cell wall with a spatial resolution of 5-6 p,m [264, 265] and maps of a hair cross section with a spatial resolution of 3-4 p,m [266] were obtained. The distribution of certain species such as proteins, lipids, and nucleic acids inside single living cells (some of which are mitotically active) [267, 268] was investigated... 

Biofilms usually consist of water, microorganisms and extracellular polymeric substances (EPS). These EPS react with water to build-up hydrogels. The hydrogels form a slime that coats the microorganisms inside. Within that coating nutrients, metabolites, or further substances may be present. The EPS consist of polysaccharides, proteins, lipids and nucleic acids. 

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