摘要:

AbstractTheoretical treatment of resonance interaction of amide‐I vibration has been done in a dipole–dipole approximation on the basis of perturbation theory. A single infinite antiparallel‐chain pleated sheet as well as different kinds of its finite fragments have been considered. A good agreement has been obtained between calculated spectral parameters of amide I of the infinite sheet and observed ones in infrared and Raman spectra of synthetic polypeptides and fibrous proteins. A theoretical dependence of the resonance frequency shift of the main component and frequency splitting of two components active in the infrared spectra on the number of polypeptide chains in the finite sheet has been

ISSN:0006-3525    

DOI:10.1002/bip.1976.360150402

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

年代:1976

数据来源: WILEY

摘要:

AbstractResonance vibrational interactions of amide I for the parallel‐chain pleated‐sheet structure have been treated on the basis of the perturbation theory in a dipole–dipole approximation. The infinite sheet and finite fragments of different types have been considered. The possibility of experimental observation by infrared spectra of parallel‐chain pleated‐sheet fragments in globular proteins is

ISSN:0006-3525    

DOI:10.1002/bip.1976.360150403

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

年代:1976

数据来源: WILEY

摘要:

AbstractAmide‐I and II vibrations of α‐helix have been treated on the basis of the perturbation theory in a dipole–dipole approximation. The infinite helix and its finite fragments have been considered as models. The calculated infrared spectra for the infinite helix are in good agreement with the spectra of synthetic polypeptides. In the case of finite fragments of the α‐helix, the characteristic contours of the amide‐I and II bands appear when the nuimber of peptide groups is about 10 and 6, r

ISSN:0006-3525    

DOI:10.1002/bip.1976.360150404

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

年代:1976

数据来源: WILEY

摘要:

AbstractThe stability constant of the complex of tRNA with 50Ssubunits of ribosomes was compared in ordinary and heavy water. A considerable effect (about fourfold) was observed, showing the importance of hydrogen bonds in this interaction. In addition, the isotope effect of complementary polynucleotide interaction was measured for two examples. In the case of the binary complex of heptainosinic acid oligomers with poly(C) in the presence of 10−3MMgCl2, the transfer from ordinary to heavy water gave an increase of the stability constant of about 5%. But in the case of a ternary complex of hexaadenylic acid with poly(U) under the same conditions, the stability constant in D2O increased threefold. The isotope effect depends strongly on magnesium ion concentration and is possibly due to some specific mechanism of magnesium ion complexing involving water molecule

ISSN:0006-3525    

DOI:10.1002/bip.1976.360150405

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

年代:1976

数据来源: WILEY

摘要:

AbstractA high‐resolution plotter of differential melting profiles of DNA, RNA, or related biopolymers with an on‐line mini‐computer is described. With this device, more than 15 transition steps were identified in the thermal melting profile of DNA from bacteriophage lambda. These fine structures were found to be reproducible, and some of them disappear in the deletion mutant.To Examine the melting profile, computer simulations for several hypothetical polynucleotide sequences were performed, and compared with experimental data. The sharp peaks that appeared in the differential melting profile of λ DNA may come from some homogeneous sequences of 500 bases or

ISSN:0006-3525    

DOI:10.1002/bip.1976.360150406

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

年代:1976

数据来源: WILEY

摘要:

AbstractThe rates of cyclization of two terminally repetitious phage DNA molecules, T7 and T1, were determined and compared with earlier studies of λ DNA. Though differing over 200‐fold in the number of complementary nucleotides in the single‐chain terminals, these three DNA's cyclize at about comparable rates, suggesting that excluded volume effects are significant. The first order rate constants for T7 and T1 are strictly dependent on solvent viscosity, consistent with a diffusion limitation of the rate determining step. Whole molecules with exposed single‐chain terminals were shear‐broken to half‐molecules and the second order rate constants for joining were measured. The rates for T7 and T1 were nearly equivalent and some tenfold slower than predicted, suggesting that the long double‐helical region appended to the renaturing regions and perhaps other undetermined factors retard the rate of joining of ha

ISSN:0006-3525    

DOI:10.1002/bip.1976.360150407

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

年代:1976

数据来源: WILEY

摘要:

AbstractProtamine·DNA complexes in film and in solution have been investigated by means of infrared linear dichroism, ultraviolet circular dichroism, and laser Raman spectroscopy. At high relative humidity and in solution both infrared linear dichroism and ultraviolet circular dichroism indicate the presence of a modified B form of DNA (designated as B* in our other papers27,28,46). This modified B form is characterized by a change of the orientation of the\documentclass{article}\pagestyle{empty}\begin{document}$ \widehat{OPO} $\end{document}bisector angle by about 4° with respect to the helical axis when compared to the B form of DNA. At decreasing relative humidities the same modified B form is maintained and no structural transitions B → A (or B → C) normally occurring in free DNA were observed. The absence of the A form in these complexes was also confirmed by laser Raman scattering studies of protamine·DNA complexes. On the basis of these results, a model of the protamine·DNA complex is proposed, which suggests that the presence of apolar amino‐acid residues, and probably the folding of the polypeptide chain, is responsible for preventing the B‐to‐A transition; this occurs either by protecting the high‐humidity modified B form against dehydration or by steric interference of this protein probably located in one of

ISSN:0006-3525    

DOI:10.1002/bip.1976.360150408

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

年代:1976

数据来源: WILEY

摘要:

AbstractOur studies on the solution conformation of (Gly‐Pro‐Sar)nand (Gly‐Sar‐Pro)nsynthesized as polypeptide models for collagen are reported. It is found that, while (Gly‐Pro‐Sar)nexists in ordered triple‐helical conformation, (Gly‐Sar‐Pro)nremains as a disordered random coil in water. Addition of certain helix‐promoting solvents seems to generate orde

ISSN:0006-3525    

DOI:10.1002/bip.1976.360150409

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

年代:1976

数据来源: WILEY

摘要:

AbstractSedimentation velocity runs as a function of temperature in the region of the alkaline helix‐coil transition have enabled us to demonstrate the existence of stable two‐stranded intermediates in the strand‐separation process for T7 DNA. The strand‐separation transition under these conditions has an intrinsic breadth of ∼1°C, and within this temperature range (Tm+ 2°C

ISSN:0006-3525    

DOI:10.1002/bip.1976.360150410

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

年代:1976

数据来源: WILEY

摘要:

AbstractSeveral research groups have explored the action pattern of depolymerizing enzymes by examining the distribution of products during the early stages of digestion. Mathematical models for the various mechanisms that have been proposed for the behaviour of depolymerizing enzymes are developed in this paper. Published data for several amylases are reexamined in light of this theoretical analysis. It is concluded that following an initial random attack on a long polymer substrate, the enzyme frequently releases only one of the substrate fragments. The retained fragment may be repetitively hydrolyzed near one end to release a series of oligosaccharides before the enzyme substrate–fragment complex finally dissociates. Near optimum conditionsBacillus subtilis(var.amyloliquefaciens) amylase is unique among the enzymes tested because it does not repetitively attack substrate fragment

ISSN:0006-3525    

DOI:10.1002/bip.1976.360150411

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

年代:1976

数据来源: WILEY