ISSN:0006-3525    

DOI:10.1002/bip.360250202

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

年代:1986

数据来源: WILEY

ISSN:0006-3525    

DOI:10.1002/bip.360250203

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

年代:1986

数据来源: WILEY

ISSN:0006-3525    

DOI:10.1002/bip.360250204

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

年代:1986

数据来源: WILEY

ISSN:0006-3525    

DOI:10.1002/bip.360250205

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

年代:1986

数据来源: WILEY

摘要:

AbstractPermittivity ε′ and dielectric loss ε″ of aqueous Na‐DNA gels have been measured at 10 GHz in the temperature interval −15 to + 45°C. The experimental results are analyzed in terms of a three‐component equation (Na‐DNA, interfacial water, bulk water) and yield a value of 35 water molecules/nucleotide interacting with DNA. According to theoretical and experimental data the presence of strongly bonded and weakly bonded water is considered. The modified water exhibits a mean dielectric relaxation time two‐or threefold greater than th

ISSN:0006-3525    

DOI:10.1002/bip.360250206

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

年代:1986

数据来源: WILEY

摘要:

AbstractWe present molecular mechanical calculations on the complexes of netropsin with dA6·dT6, d(TATATA)2, d(CGCGCG)2, and d(CGCGAATTCGCG)2. The complexes were model built using computer graphics and then completely energy refined. Our calculations are consistent with the observed AT preference for netropsin and suggest that mixed sugar pucker geometries should be more stable than uniform in netropsin complexes with poly[d(A‐T)]·poly[d(A‐T)]and poly(dA)·poly(dt). The netropsin·d(TATATA) and netropsin·dA6·dT6complexes are significantly different in structure, leading to a possible reason why the observed thermodynamics of netropsin‐association with poly[d(A‐T)]·poly[d(A‐T)]and with poly(dA)·poly(dT) are so different. We also model built and energy refined a structure of netropsin‐d(CGCGAATTCGCG)2using as a guide the nmr data of Patel [(1982)Proc. Natl. Acad. Sci. USA,79, 6424–6428] and found a three‐dimensional structure qualitatively consistent with the NOE enhancements observed by him. After our calculations were completed, we learned of an x‐ray structure of a netropsin:d(CGCGAATTCGCG)2complex, and we compared the structure found in our calculation

ISSN:0006-3525    

DOI:10.1002/bip.360250207

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

年代:1986

数据来源: WILEY

摘要:

AbstractWe present molecular mechanical calculations on 2,6‐diaminopurine (2,6‐DAP):uracil (thymine) and 8‐methyladenine (8‐methyl A): uracil (thymine) hydrogen‐bonded complexes of various geometries, namely, Watson‐Crick (normal and reverse), Hoogsteen (normal and reverse), and purine N3 type. In contrast to earlier calculations [Ornstein, R. L.&Fresco, J. R. (1983)Proc. Natl. Acad. Sci. USA80, 5171–5175], the 2,6‐DAP:uracil (thymine) complexes are predicted to be Watson‐Crick and the 8‐methyladenine:uracil (thymine) to be Hoogsteen. The results presented here are more consistent with the observed crystallo

ISSN:0006-3525    

DOI:10.1002/bip.360250208

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

年代:1986

数据来源: WILEY

摘要:

AbstractSelf‐association of Nα‐protected peptides related to C‐terminal sequences of substance P in methylene chloride was disrupted by adding increasing amounts of various polar organic solvents. This process was monitored by the disappearance of the amide I CO stretching band (1630 cm−1) of strongly intermolecularly H‐bonded molecules in the irabsorption spectra. The effects induced by main‐chain length, incorporation at position 9 of a residue promoting folding (α‐aminoisobutyric acid), the nature of solvent, and peptide concentration were established. A corollary1H‐nmr investigation provided detailed information on the NH protons involved in the self‐association process as H‐bonding donors. The increasing propensity to aggregate exhibited by these peptides is paralleled by a decrease in their solubility. The impact of these results on the synthesis of substance P short sequen

ISSN:0006-3525    

DOI:10.1002/bip.360250209

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe effect of solvent viscosity (ηs) and temperature (T) on the shape of the concentration dependence of the principal and total recoils in creep‐recovery viscoelastometry experiments has been studied for T4 DNA solutions. The range of DNA concentration (c) was 2 – 40 μg/ml; glycerol, 70–80% v/v, sucrose, 60% v/v; NaCl, 5 mM– 1M; andT, 275 – 323 K. A linear proportionality between recoil andcwas obtained at high ηs/T. At low ηs/T, thec‐dependence was nonlinear, approaching saturation at higherc. At lowc, the slope of both curves was the same. Transition between “linear” and “nonlinear” values occurred over a narrow range of ηs/T(a width of 1–5 K if ηs/Twas changed by varyingT). (ηs/T)tr, the midpoint of the transition, was independent of solvent properties other than viscosity. Also, (ηs/T)trincreased withc. For a givenc, ηs/Tvalues above this transitional value yield linear behavior; below this, nonlinear behavior. The ratio of linear to nonlinear recoil values is a linear function ofcwithKc, the slope of this dependence, independent of ηsandT. A kinetic model for the observed nonlinearity of recoil withcis presented. It explains the independence ofKcon ηsandT. An attempt has been made to explain the linear–nonlinear transitions by comparison of τ1andTR, the lifetime of the contact points of the polymer network in the de Gennes theory. The nonlinear values are consistent with a pseudogel that exists when τ1TR, the DNA behavior is similar to that in dilute solutions (linear values). Thus, the condition for transition is τ1=TR.

ISSN:0006-3525    

DOI:10.1002/bip.360250210

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

年代:1986

数据来源: WILEY

摘要:

AbstractWe utilize the dynamic quenching of the triplet state of methylene blue by molecular oxygen to observe changes in the rate at which oxygen can penetrate the helix as a function of base‐pair composition. The results indicate that the interior of the oligonucleotide dA‐dT is more accessible than dG‐dC to small molecules such as dio

ISSN:0006-3525    

DOI:10.1002/bip.360250211

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

年代:1986

数据来源: WILEY