targets are not equally sensitive, however. The reaction cross sections for the four above reactions are different at the nucleotide level, and ordered structure alters the reaction cross sections still further in nucleic acids.68 It is not surprising, then, that the irradiation conditions play an important role on the photochemistry of tRNAala bab* In dilute salt, inactivation of alanine acceptor activity is rapid and complex.9 The inactivation shows a D20 isotope effect of 1.8, an indication that photohydration is an inactivating event.9 Although the photoproducts formed under these conditions have not been examined further, it is probable that most of the targets shown in Figure 1 react.

Considerable amounts of ammonia may be formed during the alkaline hydrolysis of proteins. Osborne, Leavenworth, and Brautlecht (1) were of the opinion that the amide and guanidine groups of the protein were the sole source of this ammonia.” In the alkaline hydrolysis of wheat gliadin, however, Vickery (2) observed a slow formation of ammonia from unidentified sources. The significance of the observation was masked by the unusually large amount of amide nitrogen in this protein. In the report which follows, we present evidence that considerable amounts of ammonia may originate in groups other than amide and guanidine. A part of this may plausibly be attributed to partial deamination of cystine (3, 4), histidine (5), and serine (6). The evidence indicates, however, that a notable part-and that liberated under quite mild conditions of hydrolysis-originates in some structural feature of the protein itself, rather than in any specific amino acid component. The proteins studied were crystalline preparations of egg albumin, edestin, and fl-lactoglobulin.2

Some properties of a phage, PAV-1, that infects both Azotobacter vinelandii strains O and OP have been examined. It contains linear, double-stranded DNA that has a molecular weight of 29 × 106, a sedimentation coefficient, s20,w,Na+0, of 33.8 S and a buoyant density in CsCl of 1.716. The phage appears in electron micrographs to be icosahedral with a short tail surrounded by tail fibers. The virion is calculated to have a weight of about 74 × 106. PAV-1 is unrelated serologically to the Azotobacter phages A14, A21, A31, and A41.

Phenotypically converted pseudolysogens are formed when Azotobacter vinelandii strain O is infected with phage A21. The segregation of phage-sensitive host cells that occurs when the pseudolysogen is grown in phage-specific antiserum was studied in two isolates of pseudolysogens that had different rates of segregation. The segregation appears to be based on the random partitioning at cell division of a number of carrier particles such that a daughter cell that does not receive one reverts to the host phenotype. Values for the copy number for two isolates were determined by analysis of the kinetics of segregation. The copy number of 5 for the more rapidly segregating isolate is in agreement with a determination by hybridization that there are about four copies of phage-specific DNA per cell. In a process independent of segregation, pseudolysogens can become stably converted to a species designated here as PC cells. These cells retain the converted phenotype of the pseudolysogen but they can no longer produce phage or segregate host cells. They contain less than one genome equivalent of phage DNA. Some observations have been made on the conditions of formation of PC cells and on their loss of phage-forming ability, but the basis of the underlying process has not been clarified.

Heteroduplexes between the viral DNA of phiX174 and DNA from the replicative form (RF) of phage G4 were examined by electron microscopy. The single Eco RI site of G4-RF was utilized as a physical marker by preparing the heteroduplexes from the denatured, linear DNA obtained by restricting G4-RF with Eco RI endonuclease. Restriction fragments of phiX were used in a separate series of heteroduplexes to align the heteroduplex map and the G4 Eco RI site with the similar genetic maps of the two phages. The positions of the branch migrating junctions of recombinant phiX-G4 figure-8s, previously located only with respect to the G4-Eco RI site, have now been located with high proability within the gene A region of the two genomes. The degree of mismatch between the known nucleotide sequences of phi X and G4 accounts for positions of all of the regions of single-strandedness in the observed heteroduplexes, but unexplained discrepancies were also found.

The origin of the dimeric species of replicative form (RF) DNA has been investigated by coinfecting E. coli with phages φX174 and G4. The RF DNA from the coinfection was examined by electron microscopy before and after treatment with the EcoRl restriction endonuclease which makes one double-strand scission per monomer length in G4-RF and none in φX174-RF. Recombinant dimer molecules were identified by the unique products resulting from digestion. Circular, catenated, and figure-8 dimers were indicated to be formed both by recombination and replication. Analysis of the tail lengths of a forms derived from homozygous and heterozygous figure-8s demonstrates that branch migration is restricted by the nonhomologous regions of the G4 and φX174 genomes. No bias was detected in figure-8s with respect to the polarity of the strand that is of dimer length.

The six plasmids of Shigella dysenteriae Y6R were separated by sucrose gradients into five fractions containing deoxyribonucleic acid (DNA), having contour lengths (expressed in units equal to the fraction of the length of the replicative form of φX174), respectively, of 0.29, 0.35, 0.74, 1.08, and a mixture of 5.7 and 7.2. DNA-DNA hybridization on nitrocellulose filters between each of the plasmids and between plasmid-free S. dysenteriae Y6R host DNA and plasmids was investigated. There was a high degree of homology between the 0.29- and 0.35-unit plasmids. No significant homology was found between any of the other pairs of plasmids. Homologous DNA to the extent of 2.4 copies of the 1.08-unit plasmid was found in the host genome. Homology between the other plasmids and the host genome is very slight, but appears to be significant. About 0.7 of the 1.08-unit plasmid is homologous to the ColE1 façtor of Escherichia coli JC411 (ColE1). This plasmid may be defective ColE1 factor with the immunity function intact, but with a defect in the gene leading to the production of active colicin. Electron microscope examination of heteroduplexes formed between the two smallest plasmids and between the 1.08-unit plasmid and the ColE1 factor yielded independent determinations of the extent of homology in agreement with the values determined by hybridization. In the latter case, two nonhomologous regions of substitution of DNA were detected.

Azotobacter phage A14 consists of a large polyhedral head and a contractile tail. It contains 34% DNA and has a particle weight of 470 × 106 daltons. Details of the head and tail structure were revealed by negative staining. Staining and fixed angle shadowing indicated that the head has icosahedral symmetry. Selective nucleation showed that the internal rod of the tail has a bilayer structure that inserts into the head. Exposure of A14 virions to high ionic strength results in disruption of the head, release of the DNA, and fragmentation of the tail components.

The properties of several Azotobacter vinelandii phages and of the DNA isolated from each have been investigated. Phages A12, A21, and A41 have short noncontractile tails. A12 and A21 have virion weights of 80 × 106 daltons and contain 58% DNA. A31 has a long noncontractile tail, a virion weight of 175 × 106 daltons and contains 26% DNA. A31 and A41 are unstable in salt solutions of moderate ionic strength. All phages contain linear, double-stranded DNA that sediments as a single component in neutral and alkaline solutions. The molecular weights of A12, A21, and A31 DNAs obtained by equilibrium density gradient sedimentation are (46 ± 7) × 106, (42 ± 5) × 106 and (47 ± 5) × 106, respectively. Electron microscope length measurements using the replicative form of ∅X174 DNA as an internal contour length standard yielded molecular weights of (44.3 ± 2) × 106, (45.6 ± 1.2) × 106 and (46.5 ± 2.6) × 106, respectively. The buoyant densities of A12 and A21 DNA in CsCl and Cs2SO4 indicate a G + C content of 58% consistent with the Tm. For A31 DNA the buoyant densities suggest a G + C content of 52% whereas the Tm corresponds to 69% G + C. A12 and A21 DNAs show strand separation in an alkaline CsCl gradient (Δρ⋍0.006 g ml−1).

The frequency of occurrence of circular dimers, catenated dimers and higher oligomers has been determined in preparations of the covalently closed, circular DNA of the replicative form of the bacteriophage φX174. Fifty minutes after infection in the presence of chloramphenicol, 2.3, 1 and 0.3%, respectively, of the three types of molecules were present. The conditions for preparing the specimens for electron microscopy and the criteria for distinguishing circular and catenated dimers on micrographs have been formulated so that they can be uniformly applied in a survey of a large number of molecules.

The closely related bacterial viruses ϕX174 and S13 (Tessman and Shleser, 1963; Zahler, 1958; Tessman, 1959) each contain one molecule of single-stranded circular DNA as their only genetic component. Since this characteristic is not typical of most DNA-containing viruses, or of prokaryotic and eukaryotic cells in general, it has been of considerable interest to investigate the mechanisms by which these small viruses replicate and recombine. Specifically, one might ask whether unique processes are operative, or if the now classical mechanisms of semiconservative replication and breakage and reunion of DNA duplexes are responsible for these fundamental events.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Kinetics of Denaturation of Conalbumin1Arnold Wishnia and Robert C. WarnerCite this: J. Am. Chem. Soc. 1961, 83, 9, 2065–2071Publication Date (Print):May 1, 1961Publication History Published online1 May 2002Published inissue 1 May 1961https://doi.org/10.1021/ja01470a010Request reuse permissionsArticle Views84Altmetric-Citations13LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (802 KB) Get e-Alertsclose Get e-Alerts

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Hydrogen-ion Equilibria of Conalbumin1Arnold Wishnia, Ione Weber, and Robert C. WarnerCite this: J. Am. Chem. Soc. 1961, 83, 9, 2071–2080Publication Date (Print):May 1, 1961Publication History Published online1 May 2002Published inissue 1 May 1961https://pubs.acs.org/doi/10.1021/ja01470a011https://doi.org/10.1021/ja01470a011research-articleACS PublicationsRequest reuse permissionsArticle Views47Altmetric-Citations51LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Annals of the New York Academy of SciencesVolume 88, Issue 3 p. 741-744 INTRACELLULAR SITES FOR AMINO ACID INCORPORATION INTO PROTEINS* Renzo Rendi, Renzo Rendi Department of Biochemistry, New York University College of Medicine, New York, N. Y.Search for more papers by this authorRobert C. Warner, Robert C. Warner Department of Biochemistry, New York University College of Medicine, New York, N. Y.Search for more papers by this author Renzo Rendi, Renzo Rendi Department of Biochemistry, New York University College of Medicine, New York, N. Y.Search for more papers by this authorRobert C. Warner, Robert C. Warner Department of Biochemistry, New York University College of Medicine, New York, N. Y.Search for more papers by this author First published: August 1960 https://doi.org/10.1111/j.1749-6632.1960.tb20067.xCitations: 9 * The work reported in this paper was supported in part by Grant NSF-G-9621 from the National Science Foundation, Washington, D. C. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat References 1 SIEKEVITZ, P. 1952. J. Biol. Chem. 195: 549. 2 LITTLEFIELD, J. W., E. B. KELLER, J. GROSS & P. C. ZAMECNIK. 1955. J. Biol. Chem. 217: 111. 3 ALLFREY, V. G., A. E. MIRSKY & S. OSAWA. 1957. J. Gen. Physiol. 40: 451. 4 LOGAN, R., A. FICQ & M. ERRERA. 1959. Biochim. et Biophys. Acta. 31: 402. 5 MCLEAN, J. R., G. L. COHN, I. K. BRANDT & M. V. SIMPSON. 1958. J. Biol. Chem. 233: 657. 6 GREENGARD, O. & P. N. CAMPBELL. 1959. Biochem. J. 71: 148. 7 RENDI, R. & T. HULTIN. Exptl. Cell Research. In press. 8 RENDI, R. 1959. Exptl. Cell Research. 17: 585. 9 RENDI, R. Exptl. Cell Research. In press. 10 HOAGLAND, M. B., M. L. STEPHENSON, J. F. SCOTT, L. I. HECHT & P. C. ZAMECNIK. 1958. J. Biol. Chem. 231: 241. 11 HALL, B. D. & P. DOTY. 1959. J. Molecular Biol. 1: 111. 12 GIERER, A. 1958. Z. Naturforsch. 13b: 778. 13 HOPKINS, J. W. 1959. Proc. Natl. Acad. Sci. 40: 1461. Citing Literature Volume88, Issue3Amino Acids, Peptides, and ProteinsAugust 1960Pages 741-744 ReferencesRelatedInformation

Amino acid incorporation into protein of particulate fractions of Azotobacter vinelandii, both in experiments with intact cells and with the isolated fractions, is much faster in a fraction sedimented in low gravitational fields (fraction A), which appears to consist mainly of fragmented cell membranes and walls, than in one consisting of small particles (fraction C) which resemble the amino acid incorporating ribonucleoprotein particles of animal and plant cells, in sedimentation properties and composition. The active components of fraction C may be ribonucleoprotein particles detached from the cell membranes during disintegration of the bacteria and their amino acid incorporating activity may be much lower when they are free than when they are associated with the cell membrane.