摘要:

AbstractThe range of application of the Manning theory of polyelectrolyte solutions (J. Chem. Phys.,51, 924 (1969)) is extended to finite concentrations of simple electrolyte by the empirical superposition of excess free energies arising from (i) interactions between mobile ions and polyions and (ii) mutual interactions between mobile ions. A comparison of published results with the modified theory shows excellent agreement over a wide range of concentrations. Results for a polyelectrolyte of low charge density suggest that the effective inter‐charge spacing may be less than that of the fully extended polyio

ISSN:0006-3525    

DOI:10.1002/bip.1973.360120202

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

年代:1973

数据来源: WILEY

摘要:

AbstractDifferential enthalpic analysis of a series of 3′,5′‐cyclic nucleotides indicates that homolytic cleavage of the six‐membered phosphate ring occurs either immediately prior to or concurrent with decomposition of the crystal lattice. Homolysis is followed by a rapid polymerization to yield oligonucleotides. The enthalpies of these reactions have, with the exception of guanosine 3′,5′‐cyclic phosphate, almost identical values of 25 kcal/mole. The anomalous case is attributed to a more stabilized phosphate ring as a result of hydrogen bonding through the two position of the purine ring. The pair of overlapping exothermic peaks observed in each of the thermograms for cAMP and cIMP is related to the presence of two conformational arrangements within the unit cell of

ISSN:0006-3525    

DOI:10.1002/bip.1973.360120203

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

年代:1973

数据来源: WILEY

摘要:

AbstractElectron‐microscopic studies of some proteid structures (synthesized in RF electrical discharge) and corresponding individual compounds resulting from acid hydrolysis were investigated. Some superior precellular structures with peptide linkages in cold plasma conditions were observe

ISSN:0006-3525    

DOI:10.1002/bip.1973.360120204

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe total energy and the electronic properties of somesynpurine nucleosides have been determined as a function of the rotation angle around the C–N glycosidic linkage. Invariably, the crystallographic coordinates provide a state lying at or very near the minimum on the potential energy curve according to the extended Hückel parametrization here employed. The ribose moiety always carries a net positive charge whereas the base is always negatively charged. Changes in dipole moment magnitudes for the overall structure as well as in net atomic charges are noted upon rotation around the glycosidic linkage indicating that potential functions for polynucleotides may be in error if such changes are ignor

ISSN:0006-3525    

DOI:10.1002/bip.1973.360120205

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

年代:1973

数据来源: WILEY

摘要:

AbstractPrevious work on the thermodynamics of small systems is applied to the binding of ligands on dilute polymer molecules in solution, and especially to the binding of complementary monomers and oligomers on polynucleotides. Topics emphasized are: binding isotherms, optical melting curves, calorimetric melting and mixing studies, role of the activity of the ligand, quasi phase transitions, the polymer phase diagram, and interrelations between these subjects. The one‐dimensional Ising model (linear and circular) is used to illustrate some of the thermodynamics. An Appendix shows how the ligand activity in salt solution may be found from vapor pressure osmometry measurement

ISSN:0006-3525    

DOI:10.1002/bip.1973.360120206

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

年代:1973

数据来源: WILEY

摘要:

AbstractA general theory of helix–coil transition of irreversibly complexed nucleoproteins is presented. The equations are tested by experimental results in basic polypeptide–DNA complexes, nucleohistone I and pea bud nucleohistones. They show good agreement between theory and experiments. The theory provides direct measurement of a fraction of DNA base pairs covered by proteins, yielding a value of about 75% histone‐covered base pairs in pea bud nucleohistone. It also provides a measurement of an average number of amino acid residues per nucleotide in protein‐bound regions. This number varies from 1.0 to 1.4 in DNA–polylysine or DNA–polyarginine and from 2.9 to 3.3 in nucleohistone Ia, Ib, f1, and pea bud nu

ISSN:0006-3525    

DOI:10.1002/bip.1973.360120207

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

年代:1973

数据来源: WILEY

摘要:

AbstractConformational energies of the 5′‐adenosine monophosphate have been computed as a function of χ and ψ, of the torsion angles about the side‐chain glycosyl C(1′)–N(9) and of the main‐chain exocyclic C(4′)–C(5′) bonds by considering nonbonded, torsion, and electrostatic interactions. The two primary modes of sugar puckering, namely, C(2′)‐endoand C(3′)‐endohave been considered. The results indicate that there is a striking correlation between the conformations about the side‐chain glyocsyl bond and the backbone C(4′)–C(5′) bond of the nucleotide unit. It is found that theantiand theGauche–Gauche(gg), conformations about the glycosyl and the C(4′)–C(5′) bonds, respectively, are energetically the most favored conformations for 5′‐adenine nucleotide irrespective of whether the puckering of the ribose is C(2′)‐endoor C(3′)‐endo. Calculations have also shown that the other common 5′‐pyrimidine nucleotides will show similar preferences for the glycosyl and C(4′)–C(5′) bond conformations. These results are in remarkable agreement with the concept of the “rigid” nucleotide unit that has been developed from available data on mononucleotides and dinucleoside monophosphates. It is found that the conformational ‘rigidity’ in 5′‐nucleotides compared with that of nucleosides is a consequence of, predominantly, the coulombic interactions between the negatively charged phosphate group and the base. The above result permits one to consider polynucleotide conformations in terms of a “rigid” C(2′)‐endoor C(3′)‐endonucleotide unit with the major conformational changes being brought about by rotations about the P–O bonds linking the internucleotide phosphorus atom. IT is predicted that theantiand theggconformations about the glycosyl and the C(4′)–C(5′) bonds would be strongly preferred in the mononucleotide components of different purine an

ISSN:0006-3525    

DOI:10.1002/bip.1973.360120208

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

年代:1973

数据来源: WILEY

摘要:

AbstractConsistent force‐field calculations were performed on a series of methyl substituted pyrrolidones. Methyl substitution enhances the non‐planarity of the pyrrolidone ring in a way wich varies with the position of the substituent. The effect of ring distortion is to produce skeletal contributions to the rotatory strength of thenπ* transition of the amide group. Depending on position of substitution, these reinforce or oppose the substituent contribution to optical activity. There is favorable agreement between the conformational calculations and the quadrant rule for the optical activity of thenπ* transition of the peptide chromo

ISSN:0006-3525    

DOI:10.1002/bip.1973.360120209

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

年代:1973

数据来源: WILEY

摘要:

Abstract5‐Bromouracil‐substituted DNA was isolated formB. Subtilisand phage PBSH. The three DNA fractions of Different densities (TT, TB, and BB) were irradiated with u.v. (313nm). The number of single‐strand and double‐strand breaks was determined. The breakage rates are given. It was found that in hybrid DNA (TB) double‐strand breaks occur depending linearly on dose. In BB–DNA the observed double‐Strand bresks can be divided into two fractions with a linear and quadratic dose dependence respectively. The results can be explained by assuming intramolecular energy transfer from the BU‐containing strand to its compl

ISSN:0006-3525    

DOI:10.1002/bip.1973.360120210

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

年代:1973

数据来源: WILEY

摘要:

AbstractMeasuring the equivalent noise resistance of Na–DNA solutions in NaCl provides in formation about the free ino atmosphere. In an Arrhenius type diagram, the helix → coil transition is clearly brought Out. A Calculation of the number of free ions in the solution as function of temperature, reveals once more the process of ejection of compensating Na+ions form the macromolecules during the thermal transconformat

ISSN:0006-3525    

DOI:10.1002/bip.1973.360120211

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

年代:1973

数据来源: WILEY