摘要:

AbstractA series of poly(L‐glutamic acid) esters have been synthesized and studied by optical rotatory dispersion, x‐ray diffraction, and infrared spectrometry. The results obtained emphasize the importance of the outer portions of the side chains in determining both the stability and precise conformation of the α

ISSN:0006-3525    

DOI:10.1002/bip.1967.360050902

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY

摘要:

AbstractConformational energies of the poly‐N‐methyl‐L‐alanine chain have been calculated as a function of the rotational angles of its skeletal bonds, taking into account torsional potentials, van der Waals repulsions, and London attractions. Four pronounced minima in the energy were found; the relative magnitudes of the energies at these minima suggest that the preferred conformation of this chain is either a right‐handed, approximately threefold helix, or a slightly distorted, left‐handed α‐helix. Inclusion of an estimate of the dipolar contribution to the total conformational energy does not significantly affect t

ISSN:0006-3525    

DOI:10.1002/bip.1967.360050903

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY

摘要:

AbstractSterically allowed forms of the poly‐N‐methyl‐L‐alanine chain were found by calculation of conformational energies as a function of the rotation angles of its chain bonds. The lowest energy form seems to be a right‐handed, approximately threef

ISSN:0006-3525    

DOI:10.1002/bip.1967.360050904

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY

摘要:

AbstractThe optical rotatory dispersion and ultraviolet absorption spectra of the 64 trinucleoside diphosphates containing the bases A, U, C, and G have been calculated by using a simple semiempirical approach. These calculations accurately predict the optical properties of the nine trimers for which extensive experimental results are available. The computed optical data should be useful in the identification of oligonucleotides obtained in the course of sequence determination of ribonucleic acids and should simplify the determination of the concentration of oligonucleotides in aqueous solution. Additional calculations indicate that it should be possible to analyze most, mixtures of sequence isomers of trinucleoside diphosphates by direct, measurement of the ORD of the mixture at neutral pH.

ISSN:0006-3525    

DOI:10.1002/bip.1967.360050905

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY

摘要:

AbstractOriented amylose fibers in the V form were prepared and subjected to x‐ray analysis. Unit cells and the probable space group ofP212121were determined for the V anhydrous and V hydrate forms of amylose; the analysis confirms previous predictions of these structures based on x‐ray powder patterns. Chain folding in V amyloses is discussed in view of crystallographic evidence and folding experiments conducted with space‐filling models. Reported also is evidence for amylose helices having diameters intermediate between 13.0 and 1

ISSN:0006-3525    

DOI:10.1002/bip.1967.360050906

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY

摘要:

AbstractWhen increasing concentrations of methylmercuric hydroxide are added to a Cs2SO4solution of native DNA, the buoyant density of DNA is unaltered until a critical concentration is reached above which there is a cooperative transition to denatured DNA which now binds so much CH3HgOH that it becomes very dense and nonbuoyant. As increasing concentrations of methylmercuric hydroxide are added to a Cs2So4solution of denatured DNA, the buoyant density gradually increases, indicating a gradual increase in the amount of methylmercury cation bound. The denatured DNA methylmercury complex becomes nonbuoyant at the same concentration of methylmercuric hydroxide as does the native DNA. These results support our previous interpretation that CH3HgOH reacts with the imino NH bonds of thymine and guanine in nucleic acids. The reaction occurs more or less independently at the different binding sites for denatured DNA, but it occurs cooperatively with simultaneous denaturation for native DNA. The nature of the transition of denatured DNA to the nonbuoyant state is not known, but it is probably due to an abrupt decrease in the degree of hydration of the DNA when its density and hydrophobic character are sufficiently increased by the binding of the methylmercury cation. Direct measurements of the amount of methylmercury bound by DNA, as observed by preparative ultracentrifugation, confirm approximately the buoyant density results as to the amount of methylmercury bound. The possibility of using methylmercuric hydroxide as a reagent for the separation of complementary strands, depending on then thymine of their thymine plus guanine content, is discussed.

ISSN:0006-3525    

DOI:10.1002/bip.1967.360050907

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY

摘要:

AbstractThe base composition of DNA from microorganisms varies over a wide range of guanine + cytosine (G‐C) content. We have examined the infrared spectra of a number of DNA samples isolated from different microorganisms and have found marked differences in their infrared spectra. These differences have been related to the G‐C content of the investigated DNA samples. A comparison between the infrared spectra of nucleosides, synthetic polynucleotides, apurinic acid, and apyrimidinic acid has permitted a more extensive assignment of infrared bands to distinct base residues. The relative intensity of the absorption bands at 1485 and 1505 cm.−1depends on the G‐C content of the deuterated DNA sample. On the basis of these results a new method for the determination of the G‐C content in DNA has been developed from the results. Its advantage is that the measurement is rapid and the DNA samples are not changed by the

ISSN:0006-3525    

DOI:10.1002/bip.1967.360050908

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY

ISSN:0006-3525    

DOI:10.1002/bip.1967.360050909

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY

ISSN:0006-3525    

DOI:10.1002/bip.1967.360050910

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY

ISSN:0006-3525    

DOI:10.1002/bip.1967.360050901

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1967

数据来源: WILEY