Virion adsorbed

Reverse transcriptase (from avian or murine RNA tumour viruses) [9068-38-6] [EC 2.7.7.49]. Purified by solubilising the virus with non-ionic detergent. Lysed virions were adsorbed on DEAE-cellulose or DEAE-Sephadex columns and the enzyme eluted with a salt gradient, then chromatographed on a phosphocellulose column and enzyme activity eluted in a salt gradient. Purified from other viral proteins by affinity chromatography on a pyran-Sepharose column. [Verna Biochim Biophys Acta 473 1 7977 Smith Methods Enzymol 65 560 1980 see commercial catalogues for other transcriptases.]... 

The life cycle of T4 (Figure 17L) begins with adsorbing the virion to the surface of an E. coli cell. Because the bacterial cell wall is rigid, the entire virion cannot penetrate into the cell s interior. Instead, the DNA is injected by flexing and constricting the tail apparatus. Once the DNA has entered the cell, the infective process is complete, and the next phase (replication) begins. 

For evaluation of 6 we have assumed that the virus would be hexagonally closest-packed in a two-dimensional array on the adsorbent surface where 6 equals unity. The quantity x was estimated to be 50 from space filling models where approximately 3% of a 27-nm diameter icosahedral virion face is estimated, on the basis of globular protein structure (12), to approach the surface of the solid close enough to displace interfacial water molecules. If our estimate is changed to 10 or 250, instead of a most probable value of about 50, Equation 2 predicts that the AGads will be shifted by only zb 4 kj mol, which is comparable to the uncertainty given by experimental data scatter. 

The rotational and vibrational entropy of an adsorbed virion is probably somewhat less than it is in the free state. Because of this, and because the order of the system will possibly increase when the virus is... 

Other possible outcomes of the virion binding to the cell surface, in addition to dissociation, were considered in Ref. 112. While the virion is bound to the surface receptors, it can fuse with the cell membrane and deliver its genetic material into the cell. On the other hand, it can become engulfed by the cell membrane, endo-cytosed, and targeted for destruction. The fates of the virus and of the infected cell are determined by which of these three processes completes first. The kinetic scheme of the model is illustrated in Fig. 4. The virion can be in one of the N states with n bound receptors plus the non-spedficaUy adsorbed state at n = 0, from which it can completely dissociate with rate k. In addition to the transitions from the state with n bound sites to a state with n l bound sites and the dissociation from state n = 0, the process can terminate from n = N through endocytosis with... 

AAV is usually recovered from infected cells using trypsin and deoxy-cholate. Sedimentation in CsCl leads to a major AAV band at a buoyant density of 1.40 g/cm and a minor band at 1.467 g/cm. When sarkosyl was substituted for deoxycholate, the major AAV band in CsCl occurred at the same density as that of AAV purified in the usual manner. However, the amount of material in the denser minor band was increased. Virions in the minor band have been characterized as being smaller than AAV and probably have had some of the capsid stripped away (Hoggan, 1971). After sarkosyl treatment even the AAV from the major normal density band in CsCl was unable to adsorb to KB cells (less than 10% of normal) implying that an intact capsid is required for adsorption (Berns and Adler, unpublished data). 

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