Proteins tobacco mosaic virus

Antiparallel tt-helix proteins are structures heavily dominated by a-helices. The simplest way to pack helices is in an antiparallel manner, and most of the proteins in this class consist of bundles of antiparallel helices. Many of these exhibit a slight (15°) left-handed twist of the helix bundle. Figure 6.29 shows a representative sample of antiparallel a-helix proteins. Many of these are regular, uniform structures, but in a few cases (uteroglobin, for example) one of the helices is tilted away from the bundle. Tobacco mosaic virus protein has small, highly... 

Many protein molecules are composed of more than one subunit, where each subunit is a separate polypeptide chain and can form a stable folded structure by itself. The amino acid sequences can either be identical for each subunit (as in tobacco mosaic virus protein), or similar (as in the a and )3 chains of hemoglobin), or completely different (as in aspartate transcarbamylase). The assembly of many identical subunits provides a very efficient way of constructing... 

Thiosulfate sulfurtransferase, see Rhodanese Tobacco mosaic virus protein (Bloomer et al., 1978)... 

Tobacco mosaic virus protein has a small, highly twisted antiparallel j8 sheet at the base of the helix bundle, with two more helices underneath the sheet (see Fig. 72). Cytochrome bs looks remarkably similar (see Fig. 105), but the helices are much shorter. That structure could have been classified as an up-and-down helix bundle, but we have placed it in the small metal-rich proteins because its helix bundle is very small and distorted and the heme interactions appear more important than the direct helix contacts. 

Fig. 105. Examples of small disulfide-rich or metal-rich proteins (shown on the right side) compared with their more regular counterparts in other structural categories (shown at the left), (a) Tobacco mosaic virus protein, an up-and-down helix bundle (b) cytochrome bs, a distorted up-and-down helix bundle (c) trypsin domain 1, a Greek key antiparallel /3 barrel (d) high-potential iron protein, a distorted Greek key /3 barrel (e) glutathione reductase domain 3, an open-face sandwich fi sheet (f) ferredoxin, a distorted open-face sandwich f) sheet.

Redox Fe-S proteins High-potential iron protein Ferredoxin Viral coat proteins f Tomato bushy stunt virus protein I Southern bean mosaic virus protein Tobacco mosaic virus protein... 

Niu, C. I., and H. Fraenkel-Conrat C-terminal amino acid sequence of tobacco mosaic virus protein. Biochim. Biophys. Acta 16, 597-598 (1955). 

A particularly striking feature of the simplified formula of the tobacco mosaic virus (Fig. 14) is the stereotype repetition of several simple structures (combinations UI, LS, AF) which in fact represent the cornerstones of the entire molecule. A phenomenon deserving special interest (apart from a number of symmetrical sequences occurring along the whole chain) is the symmetrical arrangement of the dipeptides of the hydroxyamino acid residues at both terminals of the polypeptide chain. This relative concentration of the serine residues at the ends of the tobacco mosaic virus protein chain has been pointed out by Anderer et al. (1960) as a possible example of nonrandomness. 

Urea affects the gel as well as the state of aggregation of solutes. Stepa-now et al. (1961) have shown that formation of peptide-peptide complexes may be avoided in phenolate or alkaline urea solutions. Two peptides derived from tobacco mosaic virus protein could be separated with Sephadex only in the presence of 8 M urea. Urea need only be included in the sample solution, not in the eluting solvent (0.01 M sodium hydroxide). Upon filtration on a Sephadex G-50 column, urea and the two peptides moved as well-separated zones. The authors did not comment on the choice of G-.50. It was probably found to be superior to G-25 since urea seems to close the pores and meshes of a Sephadex gel. The reduction in effective pore and mesh size is perhaps caused by urea being bound to the carbohydrate network since the swelling is in fact increased in strong urea solutions. 

Fig. 18. Primary sequence of protein from tobacco mosaic virus protein (Anderer et al, 1960a). The multiplicity of enzymatic cleavages is indicated by C (ehymotryp-sin), P (pepsin), and T (trypsin). Cleavage by NBS is observed next to Try (17), Try (52), and to a lesser extent next to Try (152). From Ramaehandran and Witkop (1959).

The detection of optically active absorption bands is usually prevented by technical barriers, for they generally lie in the far ultraviolet region of the spectrum. Yet, largely as a result of instrumental improvements, the first measurements of Cotton effects associated with helical polypeptides have very recently been achieved. Simmons and Blout (1960) first measured a minimum in the rotatory dispersion of tobacco mosaic virus protein at 232... 

Tobacco Mosaic Virus Protein Aggregation and the Virus Assembly P. Jonathan, G. Butler, and Anthony C. H. Durham... 

Immunochemistry of the Tobacco Mosaic Virus Protein E. Benjamin ... 

Just as also in the world of the micro-units phases are known which in their degree of order occupy a place in between the crystalline and the liquid, so one also finds them with some corpuscular proteins with very extended molecules. Under various conditions tobacco mosaic virus protein can be precipitated from its solution in the form of fibrous aggregates which were first looked upon as crystals but on closer investigation proved. to be paracrystals. 

Fig. 15. Differential pulse voltammograms of tobacco mosaic virus protein at the paraffin wax-impregnated spectroscopic graphite electrode in 0.02 M sodium carbonate, pH 10.5. (A) Native protein (B) the protein denatured by 8 M urea. The protein was at the concentration of 0.1 mg/ml.

Lauffer, M. A., Optical properties of solutions of tobacco mosaic virus protein /. Phys. Chem. V42,935-944 (1938). 

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