Functions of protein

I AIM To learn about various functions served by proteins. 

The tremendous variability in the several levels of protein structure allows proteins to be tailored specifically to serve a wide range of functions, some of which are given in Table 20.2. 

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We will make real progress in understanding the structure, the properties, and the function of proteins, DMA, and RNA only if bioinformatics and chemoinformatics work together ... 

This difference m reactivity especially toward hydrolysis has an important result We 11 see m Chapter 27 that the structure and function of proteins are critical to life Itself The bonds mainly responsible for the structure of proteins are amide bonds which are about 100 times more stable to hydrolysis than ester bonds These amide bonds are stable enough to maintain the structural integrity of proteins m an aqueous environment but susceptible enough to hydrolysis to be broken when the occasion demands... 

Fig. 32. Maximum flux obtained with various protein solutions as a function of protein concentration according to equation 3. Feed flow rates, cm /min = A, 3000 B, 2000 C, 1000 and D, 500. The flux decreases exponentially as the protein concentration increases. The extrapolated protein concentration at no flux is the gel point for this type of solution (approx 28%). These results were obtained in a flow-through cell and demonstrate the...

To understand the biological function of proteins we would therefore like to be able to deduce or predict the three-dimensional structure from the amino acid sequence. This we cannot do. In spite of considerable efforts over the past 25 years, this folding problem is still unsolved and remains one of the most basic intellectual challenges in molecular biology. 

TABLE 4.5 Mass Recovery as a Function of Protein Sampie Load ... 

Biological Functions of Proteins and Some Representative Examples ... 

Creighton, T. E., 1984. Proteins Structure and Molecular Properties. New York W. H. Freeman and Co. An advanced textbook on die. structure and function of proteins. 

John.son, L. N., and Barford, D., 1993. The effects of pho.sphorylation on the. structure and function of proteins. Annual Review of Biophysics and Biomolecular Structure 22 199-232. A review of protein pho.sphorylation and its role in regrdation of enzymatic activity, with particular empha.sis on glycogen pho.sphoryla.se. 

Introduction of heme residues and different artificial receptors in protein molecules in chemical modification of structures and functions of proteins by the cofactor reconstruction method 99Ef0539. 

RNA-editing is a posttranscriptional mechanism mediated by RNA editases, which results in a site-selective deamination of adenosine to inosine. This alters codons and splicing in nuclear transcripts and thereby alters the structure and function of proteins. 

Amino acids, the building blocks of giant protein molecules have a carboxyl group and an amino group attached to the same carbon atom. A protein is a linear polymer of amino acids combined by pepfide linkages. Twenfy different amino acids are common in proteins. Their side chains, which have a variety of chemical properties, control the shapes and functions of proteins. Some of these side chains are hydrophobic, others are hydrophilic, and still others occur either on the surface or the interiors of proteins. 

Haurowitz F., The Chemistry and Functions of Proteins, Academic Press, 1963. 

FIG. 6 Comparison of protein electrophoretic mobility ratios as functions of protein molecular weight for SDS-templated gels of various compositions (data points) to Fergnson plots of reference normal gels. (Reprinted by permission of Wiley-VCH from Ref. 322, Copyright 1996, Wiley-VCH.)... 

Johnson LN, Barford D The effect of phosphorylation on the structure and function of proteins. Annu Rev Biophys Bio-mol Struct 1993 22 199. 

Section I deals with the structures and functions of proteins and enTymes, the workhorses of the body. Because almost all of the reactions in cells are catalyzed by enzymes, it is vital to understand the properties of enzymes before considering other topics. 

C. H. Schein, Solubility as a function of protein structure and solvent components, Biotechnology, 8, 308 (1990). 

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