Virus amino acid composition

If the virus is treated with proteolytic enzymes the fuzzy layer formed by the viral spikes is removed (Osterrieth, 1965 Compans, 1971 Gahm-berg et al, 1972 Sefton and Gaffney, 1974 Utermann and Simons, 1974). Remnants of both El and E2 are left in the bilayer. These have a hydrophobic amino acid composition, and are soluble in lipid solvents such as chloroform-methanol. The amphiphilic nature of the spike protein is also evident from its capacity to bind Triton X-100 (0.6 g/g protein) which binds to the hydrophobic part to form a water-soluble protein-detergent complex (Simons et al., 1973a). The ability of amphiphilic proteins to bind Triton can be used to separate them from hydrophilic proteins using an extraction procedure recendy described... 

The abnormal deposits found in the brains of CJD victims consist of an abnormal isoform of PrP. Prion protein is normally found in cells. Detailed structural studies show that normal cellular PrP (PrP ) is a soluble protein whose conformation is rich in a-helices with very little P-sheet. The PrP protein extracted from the brains of CJD victims (i.e., PrP ) is identical in primary amino acid sequence to the normal PrP (PrP ). However, PrP has a much greater content of P-sheet conformation with little a-helical structure. Thus PrP is neurotoxic because of its three-dimensional structure. When the prion protein is predominantly in an a-helical conformation it is nontoxic when the prion protein is predominantly in a P-sheet conformation, it kills neurons. The prion protein is thus made neurotoxic not by its amino acid composition but by its conformation. This concept is both fascinating and terrifying. Prion diseases are transmissible thus prions are infectious agents. However, prions are not like bacteria or viruses, or other infectious microbes—they are simply protein molecules. Prions are not microbes with cell membranes and nucleic acids they are not living things. Indeed, prions are not even infectious molecules, they are infectious molecular shapes. 

In no case is the amino acid composition of a sialidase yet known, and complete insight into the amino acids involved in enzyme catalysis is unavailable. There is one report demonstrating a possible involvement of tryptophan residues in enzyme catalysis.331 Establishing of the complete, amino acid sequence of sialidases from different sub-types of influenza virus is to be expected from the determination of the nucleotide sequence of the viral genome by using a plasmid technique.332 Preliminary results revealed the identity of the first 12 amino... 

The unique Hyp residue may be important both at the molecular and higher-order structure levels in collagen. Bacteria and viruses lack prolyl hydroxylase and have no hydroxyproline in their collagen-like domains. The significant differences in their amino acid composition and sequence compared to animal collagens suggest the use of alternative stabilization strategies for the triple helix (Rasmussen et al., 2003). 

Amino acid composition of southern bean mosaic virus. Contribs. Boyce Thompson Inst., 18, 371 (1956). With Beatrices. Magdoff and Diane Block Montie. 

About two-thirds of colds are caused by rhinoviruses - members of the picomavirus group (as are the polio viruses), and all of them are RNA-(+)-viruses. These have an icosahedral (20-sided, near-spherical) shape and their protein coat is made from four different proteins with widely differing amino acid compositions. It is not therefore surprising that there are more than 90 serotypes hence, there is little possibility of a useful vaccine, and none of us has much chance of becoming immune to all forms of the common cold. Other viruses that produce the symptoms of a cold include coronaviruses, adenoviruses, coxsackie viruses, orthomyxoviruses, paramyxoviruses, respiratory syncitial viruses, echoviruses and enteroviruses. 

The amino acid composition has not been established for any picornavirus VPg. It is noteworthy, however, that polio VPg lacks methionine. This property contributed to the delay in the discovery of the protein since during the search for the methylated capping oup attempts were made to label polio virion ENA with ( methyl-5H)Met in vivo (5> 21). In contrast, VPg of foot-and-mouth disease virus (PMPV) can be labeled with methionine (22). 

It leads to considerable economy of genetic information. This can be illustrated by considering some of the smaller viruses, which might, for example, have as a genome a single strand of RNA composed of about 3000 nucleotides and a protein coat with an overall composition of some 20 000 amino acid... 

Sulphated PS, potent antiviral agents, were also evaluated in vitro as inhibitors of influenza virus replication [119], The fact that the sulphated PS are inhibitory to some myxoviruses and retroviruses but not to others seems to depend on the composition of the amino acid sequences of the viral envelope glycoproteins that are involved in virus-cell binding and fusion [120],... 

Tobacco mosaic virus is made of RNA and a protein coat. The amino acid sequence of the protein coat is dictated by the base sequence of the tobacco mosaic RNA (to determine the composition of the coat protein). Obviously, much can be learned about the control of protein synthesis by changing the composition of the template RNA. This is precisely what happens after chemical mutagens are applied. Three different mutagens have been used nitrous acid, hydroxyla-mine, and 5-fluorouracil. Among the three, the results obtained with nitrous acid are particularly interesting. 

The RNA molecule of one of the most thoroughly studied viruses, tobacco mosaic virus (TMV), has the structure of a single-stranded polynucleotide consisting of approximately 6000 nucleotides. The fact that this RNA contains the information determining amino acid sequence in the protein of the virus coat (158 amino acid residues in each protein molecule) is shown not only by the widely known and extensive data on infectivity of pure tobacco mosaic virus RNA and its ability to reproduce whole virus, but also, in a more direct form, by investigations of inherited changes in the amino acid sequence of this protein as a result of experimental modifications of flie nucleotide composition of the virus RNA by the action of nitric acid and other substances under carefully controlled conditions. Such treatment causes deamination... 

Changes in nucleotide composition are accompanied to a greater or lesser degree by strictly determined changes in the amino acid sequence of virus protein, and some very important work in this direction has been done in recent years to study the character of the amino acid code, i.e., which combinations of nucleotides of virus RNA code the position of a particular amino acid residue in the molecule of virus protein (Wittman, 1963 Wittman and Wittman-Liebold, 1963 Tsugita and Fraenkel-Conrat, 1960, 1962). 

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