Proteins and Their Constituents

Second-Order Rate Constants for the Reaction of Peroxynitrite with Various Proteins and Their Constituents... 

The liver is made up mostly of similar cells and, compared to many organs in the body, it is relatively homogeneous. Consequently, if damaged it will still function, even if only half of it is normal, but if a greater proportion of the liver is damaged or suffers dysfunction other parts of the body will suffer. One of the important functions of the liver is to remove ammonia which is toxic and results from the breakdown of proteins and their constituent amino acids. In liver failure this function is reduced, with the result that ammonia accumulates in the body and seriously affects the brain, causing convulsions and coma. 

Colour Reactions of Proteins - The colour reactions of proteins are of importance in the qualitative detection and quantitative estimation of proteins and their constituent amino acids. Biuret test is extensively used as a test to detect proteins in biological materials. 

Normal coordinate analysis has been used for many years in the interpretation of vibrational spectra for small molecules.88 It provided the motivation for the application of the harmonic approximation to proteins and their constituent elements (e.g., an a-helix).35 133-136 In this alternative to conventional dynamical methods, it is assumed that the displacement of an atom from its equilibrium position is small and that the potential energy (as obtained from Eq. 6) in the vicinity of the equilibrium position can be approximated as a sum of terms that are quadratic in the atomic displacements i.e., making use of Cartesian coordinates, which are simplest to employ for large molecules, we have... 

Chemical and biological methods can be used to estimate this parameter. Only the latter methods have a large range of applications and are able to generate data for all sources of proteins and their constituent amino acids. 

The structure of proteins (and their constituents) and the problem of semiconductivity in biopolymers... 

Three distinct types of study have been carried out in connection with the electronic structure of proteins and their constituents. In the first place, quantum-mechanical calculations have been performed on the electronic distribution in all the twenty a-amino acids which enter into the constitution of proteins " . These calculations have been carried out for the neutral, cationic, anionic and dipolar forms of the amino acids and they represent the... 

Lovkova (1964) administered uniformly labeled nicotine to N. tabacum and after 4 days recovered only 3.5% of the administered radioactivity in nicotine. About the same percentage of total radioactivity was recovered in the free amino acid fraction, which seems to have been convincingly purified from any contamination by nicotine. No separation of this amino acid mixture was undertaken, and no data were presented on the fate of the remaining majority (about 90%) of the administered radioactivity. Ill in, from the same laboratory (Ill in, 1965, 1966), reviewed his concept that the appearance of nicotine, especially in germinating seeds, and its disappearance during the maturation process have some relation to the metabolism of proteins and their constituents and that nicotine is not just a metabolic waste product. To support these hypotheses, he administered uniformly labeled [ C] nicotine to maturing fruits of Nicotiana plants. After 14 days, a radioactive protein fraction was isolated, but, because of the minute amount of nicotine in seeds and a high protein concentration, the total specific radioactivity of the isolated protein remained very low. Such incorporation of radioactivity into proteins was prevented by chloramphenicol. In later papers, more detailed experiments were described... 

There are several thermodynamic properties that are very useful for investigating solute-water interactions in aqueous solution. The partial molar compressibility of the solute is one such property. This quantity is particularly sensitive to the nature and extent of the intermolecular interactions between the solute and the solvent [74M, 94C1] and, as such, can be used to characterize the hydration of solutes in aqueous solution. The importance of compressibility measurements as a means to characterize the hydration of proteins and their constituent groups has been recognized and as a consequence of this, new results on biological compounds have been reported in recent years. In addition to this emphasis on hydration, compressibility measurements of proteins in aqueous solution are also of some importance in the study of the dynamics of globular proteins since the volume fluctuation of a protein is related to its isothermal coefficient of compressibility [76C],... 

In some cases, the forms in which the organic materials are present are not easily separated or identified. Some chemical pretreatment is necessary before the analytical procedures can be used. These pretreatments may include the preparation of volatile derivatives for use in gas chromatography, or the splitting of a large and otherwise intractable molecule, as in the hydrolysis of proteins to their constituent amino acids. 

The reader is referred to other reviews for detailed discussions of the electronic states and luminescence of nucleic acids and their constituents/0 fluorescence correlation spectroscopy/2) spectroscopy of dye/DNA complexes/0 and ethidium fluorescence assays/4,0 A brief review of early work on DNA dynamics as well as a review of tRNA kinetics and dynamics have also appeared. The diverse and voluminous literature on the use of fluorescence techniques to assay the binding of proteins and antitumor drugs to nucleic acids and on the use of fluorescent DNA/dye complexes in cytometry and cytochemistry lies entirely outside the scope of this chapter. 

Transporters, particularly those carrying nonlipophilic species across biomembranes or model membranes, can be regarded as vectorial catalysts (and are also called carriers, translocators, permeases, pumps, and ports [e.g., symports and antiports]). Many specialized approaches and techniques have been developed to characterize such systems. This is reflected by the fact that there are currently twenty-three volumes in the Methods in Enzymology series (vols. 21,22,52-56,81,88,96-98,125-127,156-157, 171-174, and 191-192) devoted to biomembranes and their constituent proteins. Chapters in each of these volumes will be of interest to those investigating transport kinetics. Other volumes are devoted to ion channels (207), membrane fusion techniques (220 and 221), lipids (14, 35, 71, and 72), plant cell membranes (148), and a volume on the reconstitution of intracellular transport (219). See Ion Pumps... 

Human perception of flavor occurs from the combined sensory responses elicited by the proteins, lipids, carbohydrates, and Maillard reaction products in the food. Proteins Chapters 6, 10, 11, 12) and their constituents and sugars Chapter 12) are the primary effects of taste, whereas the lipids Chapters 5, 9) and Maillard products Chapter 4) effect primarily the sense of smell (olfaction). Therefore, when studying a particular food or when designing a new food, it is important to understand the structure-activity relationship of all the variables in the food. To this end, several powerful multivariate statistical techniques have been developed such as factor analysis Chapter 6) and partial least squares regression analysis Chapter 7), to relate a set of independent or "causative" variables to a set of dependent or "effect" variables. Statistical results obtained via these methods are valuable, since they will permit the food... 

Drugs may be solid at room temperature (eg, aspirin, atropine), liquid (eg, nicotine, ethanol), or gaseous (eg, nitrous oxide). These factors often determine the best route of administration. The most common routes of administration are described in Chapter 3. The various classes of organic compounds—carbohydrates, proteins, lipids, and their constituents—are all represented in pharmacology. 

The study of proteins is one of the major branches of biochemistry, and there is no clear division between the organic chemistry of proteins and their biochemistry. In this chapter, we begin the study of proteins by learning about their constituents, the amino acids. We also discuss how amino acid monomers are linked into the protein polymer, and how the properties of a protein depend on those of its constituent amino acids. These concepts are needed for the further study of protein structure and function in a biochemistry course. 

Hydrolyzates of feathers and their constituent parts have also been analyzed, but there are fewer comparative data for this material. Skin keratin, horny materials, and the hard keratins of birds and reptiles have received little exact analytical investigation, although several studies of skin proteins have been reported. Difficulties in isolating the various skin structures and in defining the material studied have not encouraged precise analysis. 

During the past decade a great deal of information has been obtained on the structure of archaeal ribosomes and their constituent rRNA and r-protein components. Although these molecules share many properties with their counterparts in ribosomes from other organisms, they also show unique features which have proven to be of great value in the elucidation of the evolution of archaea in relation to bacteria and eucarya. 

Defatted tree nut meals and hulls are traditionally used as animal feeds due to their low cost and the high nutritional value of their proteins and other constituents (69). Tree nut byproducts have many food (70) and biochemical applications (71). Tree... 

This approximation implies that the nonidealities between the protein and the constituents of the mixed solvent are much stronger than those between the constituents of the mixed solvent. In other words, in this case, the main contribution to the nonideality of the very dilute mixture protein + mixed solvent stems from the nonideality of the protein with the mixed solvent and not from the nonideality of the mixed solvent itself. This means that the activity coefficients and their derivatives with respect to the concentrations in the pairs protein—water and protein— cosolvent are much larger than for the pair water—cosolvent. 

The literature on applications of NMR to problems in molecular biology now encompasses several thousand entries, and space limitations preclude a complete exposition of the subject in this article. Amino acids, peptides, proteins, nucleic acids and their constituents, polysaccharides, phospholipids, membranes, and a large range of biologically active compounds have been extensively studied by NMR. The reader interested in doing research in this field will find it necessary to consult a more extensive treatise (see, e.g.. Refs. 60, 61). Our aim here is to give only a brief introduction to the types of problems that have been studied and an outline of the methods and strategies developed for this purpose. 

I have spent at least 8 years, and millions of dollars of research funds, working on ways to deliver insulin, growth hormone, and other peptide drugs into the body without using a syringe. Any pharmaceutical company that could accomplish this feat would capture a multibillion-dollar market. There is a clear financial incentive to produce a peptide pill. However, the conclusions from this research, which are published throughout the world, remain to this day that peptides are destroyed when they enter the hostile environment of the human digestive tract. They just become another protein meal. Their constituent amino acids are absorbed for a nutritional benefit just like any other food source. 

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