Showing papers in "Advances in Protein Chemistry in 1953"

Rotational Brownian motion and polarization of the fluorescence of solutions.

Abstract: Publisher Summary The chapter discusses the rotational Brownian motion and polarization of the fluorescence of solutions. It is possible to learn something of the size and shape of protein molecules by studying their Brownian motion. Such motion involves the translation of the molecules but also their rotational movements. The Brownian motion is not observed from a study of the physical properties of the solution. When the dissolved molecules are fluorescent, a study of the polarization of the emitted radiation gives important information about rotational motion. At any instant, all possible directions are equally represented, and the molecules are thus randomly disposed. In fact, unity at the initial instant is where there is perfect orientation and reaches zero value when the orientation is random.

Peptide Bond Formation

Abstract: Publisher Summary This chapter discusses peptide bond formation. Peptide bonds may be broken and reconstituted by simple hydrolysis and its reversal by transferring reactions in which one of the participants need not be a peptide. Studies on the enzymatic synthesis of small peptides and quasi-peptides discovered examples on how free energy ultimately derived from respiration is used for peptide synthesis. A new field of investigation opened up by the finding that free amino acids are incorporated into protein by peptide linkages in the interior of the molecule. This reaction occurs in all living forms, and seen against the background of the apparent stability of protein in the cell, is remarkably rapid. The chapter discusses the bearing of these new data and new discoveries on the problem of the enzymatic synthesis of protein.

Assimilation of amino acids by Gram-positive bacteria and some actions of antibiotics thereon.

Abstract: Publisher Summary This chapter discusses the assimilation of amino acids by gram-positive bacteria. The growth of the bacterial cell involves, and is the result of, synthesis of all its components. Many bacteria can synthesize protein from ammonia and a carbon source, such as glucose. “Biochemical mutants” of molds and bacteria have indicated the probable biosynthetic pathways and individual steps in pathways that have been studied with cell-free extracts of microorganisms. Species of bacteria that are unable to synthesize amino acids, assimilates the preformed substances, to form suitable material for the study. Experimental correlations among the various processes are observed, and certain stages in the processes are found to be sensitive to antibiotics and growth inhibitors.

Naturally occurring peptides.

Abstract: Publisher Summary This chapter discusses naturally occurring peptides, which allows several generalizations concerning their importance as distinct chemical entities. Certain physiologically active naturally occurring peptides seem to be linked to the much larger protein molecules with respect to their structure and physiological activity. The distinction is based largely on the fact that naturally occurring peptides are composed of amino acids with uncommon configurations and structures, and of linkages other than the classical peptide bond. The uncommon structures exist only rarely in proteins and this would be exactly why one can use them to differentiate the naturally occurring peptides from protein fragments. One group, containing heteromeric peptides, is characterized on the basis of a common structure and an identical amino acid composition, differing from one another by the nature of the heteromeric group. Such is the case of the penicillins. Another group also has a given identical structure, but each member of the group has a different amino acid composition. All the members of such families possess the same number of amino acids, however, are of a different nature. All the members of another group possess the same heteromeric groupings and uncommon amino acids, but they differ by the number and nature of other amino acids. The characteristic biological actions of the naturally occurring peptides are because of their uncommon structures and compositions. The biological activity is related to the structure. The existence of naturally occurring peptides show that nature utilizes amino acids to build proteins and peptides.

Bacteriophages: Nature and Reproduction

Abstract: Publisher Summary This chapter discusses both subjects to build a unified concept of the nature and action of bacteriophages in relation to other viruses. The relatively simple nucleoproteins, such as the plant viruses can have virus characteristics, and the study of all viruses is bound together by a methodological unity, a similarity in biological activity, and a focus on nucleoprotein synthesis. The chemical and physical character of phage and to some extent the multiplication of phage is studied largely by the ordinary methods of protein chemistry in combination with the observation of biological phenomena. The fundamental problem of protein chemistry is the elucidation of structure in relation to biological function and mode of protein synthesis. This endeavor bacteriophage serves as a model system for the study as peptide synthesis.

Peanut Protein Isolation, Composition, and Properties

Abstract: Publisher Summary This chapter discusses the peanut protein isolation, composition, and properties. Worldwide production of peanuts exceeds 10,000,000 tons annually, with about 10% of the crop being grown in the United States. The protein content of the nuts is about 25%, which makes the peanut a significant source of vegetable protein for foods, feeds, and industrial products. Peanut protein consists of two principal fractions, arachin and conarachin. Arachin is a dissociation system, and its apparent physical chemical properties are dependent on the state of equilibrium existing between the associated and dissociated species. The chemical treatments is devised for stabilizing derived products, very little information is available on the chemical reactions of the proteins. The nutritional value of peanut protein compares favorably with other vegetable proteins; however, when compared with animal proteins, peanut protein is found to be deficient in lysine and methionine. Fibers, glues, sizings, and other industrial products have been made experimentally from peanut protein.