Characteristics of Proteins

Bell, J. E., and Bell, E. T, 1988. Proteins and Enzymes. Englewood Cliffs, NJ Prentice-Hall. This text describes die structural and functional characteristics of proteins and enzymes. 

The basic reactions of thiolsulfonates have been known for sometime (Field et al., 1961, 1964), but more recently, they have been applied to the study of protein interactions by site-directed modification of native cysteines or through modification of cysteines introduced at particular points in proteins by mutagenesis. Such studies have yielded insights into the structure and binding site characteristics of proteins (Kirley, 1989). Pascual et al. (1998) used AEAETS to probe the acetylcholine receptor from the extracellular side of the membrane in order to investigate the molecular accessibility and electrostatic potential within the open and closed channel. 

The spectral characteristics of protein conjugates made with Lissamine rhodamine B derivatives are of longer wavelength than those of tetramethylrhodamine—more toward the red region of the spectrum. In addition, modified proteins have better chemical stability and are somewhat easier to purify than those made from TRITC (discussed previously). Lissamine derivatives also make more photostable probes than the fluorescein derivatives (Section 1, this chapter). 

Cantarero, L.A., Butler, J.E., and Osborne, J.W. (1980) The adsorptive characteristics of proteins for polystyrene and their significance in solid-phase immunoassays. Anal. Biochem. 105, 375-382. 

Polymers designed with this technique have a number of important aspects in common with proteins. First of all, the transition from a liquid-like globule into a frozen state occurs as a first order phase transition. Further, the frozen state itself has an essential stability margin, which is determined by the design parameters. As in real proteins, neither a large variation of temperature or other environmental conditions, nor a mutational substitution of several monomers leads to any change in basic state conformation. In this respect the ability of sequence design to capture certain essential characteristics of proteins seems quite plausible. 

Nitrogen Solubility Index. Nitrogen solubility index (NSI) indicates the extent of denaturation of a protein and correlates well with the functional characteristics of protein ingredients. 

There are a number of methods by which you can modify the surface hydrophobic characteristics of proteins or otherwise modulate hydrophobic interactions. How they will affect a given separation is unpredictable, but they may be useful. 

Proteins have also been successfully used for chiral separations in CE. One of the characteristics of proteins is their isoprotic point, pi. The protein will mainly be charged positively if pHpI. Therefore, the pH of the BGE is a very important parameter for the optimization of the separations. As with charged-CD derivatives, it is possible to separate both charged and uncharged chiral species with... 

Pahlich, S., Bschir, K, Chiavi, C., Belyanskaya, L. and Gehring, H. (2005) Different methylation characteristics of protein arginine methyltransferase 1 and 3 toward the Ewing Sarcoma protein and a peptide. Proteins, 61, 164—175. 

The next class of cosubstrates for kinases consists of proteins. Protein kinases are very important in the regulation of cellular processes. Investigations of both these mechanisms and the roles that the protein kinases play might be aided by the use of selective inhibitors of these kinases. One indication of just how little is known about the characteristics of protein kinase-substrate interactions is the fact that many of these enzymes are named by their activators rather than by their substrates. 

Rodriguez Patino, J.M., Rodriguez Nino, M.R., Gomez, J. (1997). Interfacial and foaming characteristics of protein-lipid systems. FoodHydrocolloids, 11, 49-58. 

Many methods have been used to produce and characterize protein foams. The foaming characteristics of proteins are markedly influenced by conditions of preparation, measurement, and so forth (13-18). Because of the variety of methods employed, it is difficult to compare data from different sources. 

Jackson, R. H. and Brunner, J. R. 1960. Characteristics of protein fractions isolated from the fat/plasma interface of homogenized milk. J. Dairy Sci. 43, 912-919. 

The chemistry of the metalloenzymes must be considered as a special case of enzymic catalysis since most active sites of enzymes are stereospecific for only one molecule or class of molecules and many do not involve metal ions in catalysis. Since the metal ion is absolutely essential for catalysis in the examples chosen for this review, the mechanisms undoubtedly involve the metal ion and a particular protein microenvironment or reactive group(s) as joint participants in the catalytic event. It is our belief that studies of catalysis by metalloenzymes will have as many, if not more, features characteristic of protein catalysis in general, in a fashion similar to metal ion catalysis, and these studies will be directly applicable to heterogeneous and homogeneous catalytic chemical systems where the metal ion carries most of the catalytic function. 

Immunotechniques have recently been developed to detect food contaminants, e.g., toxins, growth hormone, antibiotics, pesticides, and herbicides. Penicillin (62) in milk, aflatoxins and mycotoxins (63, 64, 65) in milk, cheeses, yogurt, corn have been detected by immunosensors. Characteristics of protein and receptors in or on the cell surface were used in detecting pathogens such as Listeria and Salmonella by immunosensors (11, 66). The principle of immunosensors has also been applied in pesticide determinations (67, 68). 

Fujita, T., Takakura, Y., Sezaki, H. and Hashida, M. (1995) Control of disposition characteristics of proteins by direct cationization in mice. Pharm. Sci., 1, 371-375. 

With the completion of genomic DNA sequencing for various species, attention has shifted towards the structural and functional characteristics of proteins. However, rapid progress in proteomics requires the following (a) availability of many proteins, and (b) availability of sufficient amounts of proteins in naturally folded states. To meet these requirements, various existing protein production technologies have been adopted for genome-wide protein translation. 

Despite having a large number of ankyrin repeats (superseded only by the 24 repeats in ankyrin itself), a-LTX does not assume the monotonous arch-like shape so characteristic of proteins with multiple ankyrin repeats, such as the 12-repeat ankyrin fragment (Michaely et al. 2002), the human protein phosphatase HEAT (15 repeats), or the porcine ribonuclease inhibitor LRR (16 repeats) (Andrade et al. 

As already indicated, the presence of proline is apparently a common characteristic of proteins with high affinities toward tannins [68]. Proline residues, apart from being binding sites, are also useful in maintaining the peptide in extended conformation, providing more surface of the protein for binding [21]. 

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