Protein properties and functionality

H. Beinert, Iron-Sulfur Proteins Properties and Functions, in Cellular Implications of Redox Signalling , eds. C. Gitler and A. Danon, Imperial College Press, London, 2003, p. 47. 

Cytochromes c (Cyt c) can be defined as electron- transfer proteins having one or several haem c groups, bound to the protein by one or, more commonly two, thioether bonds. Cyt c possesses a wide range of properties and function in a large number of different redox processes. 

Alpha helices are sufficiently versatile to produce many very different classes of structures. In membrane-bound proteins, the regions inside the membranes are frequently a helices whose surfaces are covered by hydrophobic side chains suitable for the hydrophobic environment inside the membranes. Membrane-bound proteins are described in Chapter 12. Alpha helices are also frequently used to produce structural and motile proteins with various different properties and functions. These can be typical fibrous proteins such as keratin, which is present in skin, hair, and feathers, or parts of the cellular machinery such as fibrinogen or the muscle proteins myosin and dystrophin. These a-helical proteins will be discussed in Chapter 14. 

Cormier, M. J., and Charbonneau, H. (1977). Isolation, properties and function of a calcium-triggered luciferin binding protein. In Wasserman, R. H., et al. (eds.), Calcium Binding Proteins and Calcium Function, pp. 481-489. Elsevier North-Holland. 

Coe, N.R. and Bernlohr, D.A. (1998) Physiological properties and functions of intracellular fatty acid-binding proteins. Biochimica et Biophysica Acta 1391, 287-306. 

Filbin, M. T., D Urso, D., Zhang, K., Wong, M., Doyle, J. P. and Colman, D. R. Protein zero of peripheral nerve myelin adhesion properties and functional models. Adv. Mol. Cell. Biol. 16 159-192,1996. 

Ras and its relatives are subjects of intensive investigations by biological, biochemical, biophysical, and medical studies. Within just one decade more than 17,000 articles (Medline, 1966-2000) deal with function and properties of this protein. Structural and functional data, based on Ras as a prototype, have provided insight into the basic principles of GTP-binding proteins, their activation, de-activation, and signal transmission. 

Membrane proteins (which make up approximately one-third of the total number of known proteins) are responsible for many of the important properties and functions of biological systems. They transport ions and molecules across the membrane they act as receptors and they have roles in the assembly, fusion, and structure of cells and viruses. Presently, investigating membrane proteins is one of the most difficult challenges in the area of structural biology and biophysical chemistry. Our knowledge of membrane proteins is limited, primarily because it is very difficult to crystallize these protein systems due to the extreme hydrophobic interactions between the proteins and the membrane. New methods are needed and current techniques need to be extended to study the structural properties of membrane proteins. 

Formation of a broad range of materials with a wide variety of general or specific properties and function (such as proteins and enzymes) through a controlled sequence assembly from a fixed number of feedstock molecules (proteins about 20 different amino acids, five bases for nucleic acids, and two sugar units)... 

Protein structure and function are the topics of this and the next three chapters. We begin with a description of the fundamental chemical properties of amino acids, peptides, and proteins. 

Our understanding of protein structure and function has been derived from the study of many individual proteins. To study a protein in detail, the researcher must be able to separate it from other proteins and must have the techniques to determine its properties. The necessary methods come from protein chemistry, a discipline as old as biochemistry itself and one that retains a central position in biochemical research. 

Kinsella, J. E. 1984. Milk proteins Physicochemical and functional properties. CRC Crit. Rev. Food Sci. Nutr. 21, 197-262. 

It is often best to begin with purified proteins when studying the relationships between protein structure and function at the molecular level. The presence of multiple proteins often complicates data interpretation, as it is not clear if effects are due to protein interactions, variations in the ratio of proteins, or to other factors. In these studies it is advisable to select tests based on a fundamental physical or chemical property, since results are less likely to vary with the test conditions or instrumentation used. Unfortunately, it becomes less likely that the property under study will relate directly to function in a food system when such simplified (often dilute) systems are used. Something as seemingly insignificant as protein concentration in the model system can have a large influence on the results obtained. Also, the relative importance or contribution of a functional property to a complex food system can be misinterpreted in a purified model system. 

Mangino, M.E. 1989. Molecular properties and functionality of proteins in food emulsions. In Food Proteins (J.E. Kinsella and W.G. Soucie, eds.) pp. 157-177. American Oil Chemists Society, Champaign, 111. 

S Damodaran. Functional properties. In S Nakai, ed. Food Proteins Properties and Characterization. London VCH, 1996, pp 167-224. 

RB Gupta, IL Batey, F MacRitchie. Relationship between protein composition and functional properties of wheat flours. Cereal Chem 69 125-131, 1992. 

A powerful aspect of protein crystallography is that once the native structure is known, various cofactors or enzyme substrate analogs can be bound to the molecule in the crystal. By simply measuring the diffraction intensities, we can compute a new map that allows direct and explicit examination of the structural interactions between the native protein and its substrate or cofactor molecules. Detailed analysis of these interactions has provided much of the foundation for our current understanding of many protein catalytic and functional properties. 

Part 2, Protein Structure and Function, contains four chapters that relate to the structures and functions of proteins. In chapter 3, The Building Blocks of Proteins Amino Acids, Peptides, and Polypeptides, we discuss basic structural and chemical properties of amino acids, peptides and polypeptides. In chapter 4, The Three-Dimensional Structures of Proteins, we describe how and why polypeptide chains fold into long fibrous molecules in some cases, or into compact globular molecules in other cases. In chapter... 

Inventiveness has to be shown by the applicant or the patentee, if a lack of inventiveness is claimed by the patent examiner during the prosecution or the public in an opposition procedure. An indication of inventiveness is, for example, an unexpected result proven by comparative examples or improved properties of anew substance. Thus, if it can be shown that a new peptide or protein shows improved properties over the wild-type protein, inventiveness can usually be acknowledged. When aiming to achieve patent protection for evolutionarily designed molecules with predefined properties and functions, an inventor should keep this in mind. 

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