摘要:

AbstractA new method of measurement of the binding constant of oligonucleotides with complementary polynucleotide chains was developed using a gel filtration procedure. Data for complexing of poly U with triplets ApApA are presented and analyzed by means of a simple statistical theory of cooperative adsorption deduced by the Bethe‐Guggenheim method. The complexes are triple, they contain two polymer chains bound by oligomers. The energy of stacking is found equal to 1300 cal/mol in fair agreement with earlier data of Ts'o. The energy of binding of a single triplet to both complementary chains is equal to 14,000 cal/mo

ISSN:0006-3525    

DOI:10.1002/bip.1972.360110802

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

年代:1972

数据来源: WILEY

摘要:

AbstractValence formulas are constructed for the iron–ligand groups of the oxy‐, carboxy‐, nitric oxide‐, and nitrosobenzene derivatives of haemoglobin. To do this, the newly developed “increased‐valence” theory3is used. The most stable of these valence formulae are able to account simply for certain iron‐ligand properties, with the iron remaining essentially as ferrous, as it is

ISSN:0006-3525    

DOI:10.1002/bip.1972.360110803

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

年代:1972

数据来源: WILEY

摘要:

AbstractDielectric dispersion of polyacrylic acid (PAA) and polystyrene sulfonic acid (PSS) was measured in the presence of divalent cations. Effects of divalent ions were studied by neutralization with varying ratios of sodium hydroxide and divalent base concentration, addition of salts of divalent cations, and neutralization with divalent bases only. Two dispersion regions were observed in all cases, i.e., low‐frequency dispersion (102–104Hz) and high‐frequency dispersion (105–106Hz). The dielectric increment increases in the presence of sodium and alkaline earth metal ions together, but not with sodium and transition metal ions. This is due to the increment of low‐frequency dispersion and is attributable to the fluctuation of bound counterions which is explained by our theory previously reported.1In the case of PAA neutralized with large fractions of divalent ions, or with divalent ions only, the increment is very small because of reduction of the fluctuation by interaction between bound ions at the neighboring sites and reduction of the effective length of polyion probably due to chelation by divalent ions. There are some differences among the effects of Mg++, Ca++, and Ba++on dielectric increment which may result from affinity or chelating ability of t

ISSN:0006-3525    

DOI:10.1002/bip.1972.360110804

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

年代:1972

数据来源: WILEY

摘要:

AbstractCircular dichroism spectra of acridine orange bound toE. colitRNA were studied at varying tRNA phosphate‐to‐dye (P/D) ratios for both unfractionated and purified materials in the absence of Mg++. From the rather discrete features exhibited in the circular dichroism spectra three types of interactions were observed: (1) A high P/D ratio such as 75.2 or 49.8 indicates the interaction between the nucleotide base and dye molecule. The spectra with a large positive peak at 515 mμ are, however, quite different from that of DNA–AO complex under similar conditions. (2) With an intermediate P/D ratio (26.5 to 9.6) dye molecules bound strongly to the polynucleotide chain. (3) With low P/D ratios (≤7.5) the interaction appears to be due to the stacked dye molecules in the single‐stranded part of tRNA. The spectra of the third group have an isobestic point at 477 mμ. Below a P/D ratio of 4 the spectrum shows one positive and two negative bands which may be the characteristics of circular dichroism of stacked dyes in polynucleotide chain.Although no drastic change in the conformation of tRNA itself was detectable in the presence of Mg++in the ultraviolet region, a dramatic change was observed in the circular dichroism of tRNA–acridine orange complex when Mg++concentration was increased to 10−3M. It was inferred that certain conformational changes other than simple hydrogen bond formation occured in tRNA molecules at this high Mg++concentration, so that the amount of bound dye in the stacking condition was increased through

ISSN:0006-3525    

DOI:10.1002/bip.1972.360110805

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

年代:1972

数据来源: WILEY

摘要:

AbstractFar‐infrared spectra were measured for the sequential copolymers of amino acids with alkyl group side chains. The analysis of the spectra showed that (L‐Ala‐L‐Ala‐Gly)n, (L‐Ala‐Gly)n, (L‐Ala‐Gly‐Gly)n, (L‐Val‐L‐Ala‐L‐Ala)n, and (L‐Val‐L‐Ala)n, have the antiparallel pleated sheet structures and that the backbone conformations of (L‐Val‐L‐Val‐L‐Ala)nand (L‐Val‐L‐Val‐Gly)nare the same as that of poly‐L‐valine. The far‐infrared bands characteristic of the antiparallel pleated sheet structure were assigned on the basis of the result of the normal coordinate analysis of poly‐L‐alanine with this structure. The intersheet and interchain spacings of the sequential copolymers with the antiparallel pleated sheet structure were determi

ISSN:0006-3525    

DOI:10.1002/bip.1972.360110806

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

年代:1972

数据来源: WILEY

摘要:

AbstractPoly (L‐Prolyl‐Glycyl‐L‐Prolyl), a polymer which resembles collagen by physical and immunochemical criteria, has been shown to serve as a substrate for the highly specific bacterial collagenase obtained fromClostridium histolyticum. The postulated reaction products Gly Pro, Gly Pro Pro, and Pro Gly Pro Pro have been isolated. The enzyme has been employed as an analytical tool in elucidating the sequence of synthesized polymers of proline and

ISSN:0006-3525    

DOI:10.1002/bip.1972.360110807

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

年代:1972

数据来源: WILEY

摘要:

AbstractApparent second‐order rate constants for complex formation between poly (I) and poly (C) and copolymers of C containing non‐complementary I or U residues have been determined spectrophotometrically. The rate constants decrease as the concentration of either I or U in the C strands increases–the effect seems insensitive to the species of residue involved, when differences in the thermal stabilities of the poly (I) poly (C,I) and poly (I). poly (C,U) complexes are taken into account. These results suggest that low concentrations of relatively stable defects can alter the apparent kinetic “complexity” of polynucleotides as determined by hybridization methods (C0t

ISSN:0006-3525    

DOI:10.1002/bip.1972.360110808

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

年代:1972

数据来源: WILEY

摘要:

AbstractTwo electrophoretic components have been detected on the ascending boundary in unbuffered solutions of polyglutamic acid and polylysine under certain experimental conditions. If the conditions are favorable to aggregation, another maximum, the third in order, is formed on this boundary. We attribute this maximum to the formation of aggregates. The behavior of both boundaries and all components at various pH, concentrations, and temperature of solutions and at different molecular weights of polymers was described.

ISSN:0006-3525    

DOI:10.1002/bip.1972.360110809

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

年代:1972

数据来源: WILEY

摘要:

AbstractThe diffusional behavior of low‐molecular‐weight solutes through gel membranes containing polyanionic material has been studied as a model for connective tissue. A steady‐state isotopic flux measurement is used. Results indicate that the presence of solutions of “native” proteoglycans within a gelatin‐agarose matrix has negligible effects on the diffusion of non‐electrolytes but markedly affects the behavior of ionic species. The permeabilities of counter‐and coions are discussed in terms of a Donnan equilibrium. It is evident that not all the counterions of the polyionic salt can be regarded as mobile in terms of the Donnan effect. The polyelectrolyte theories of Katchalsky et al. are applied to the behavior of the gel membranes to explain this observation. These quantitative interpretations suggest that counterion fixation by the prote

ISSN:0006-3525    

DOI:10.1002/bip.1972.360110810

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

年代:1972

数据来源: WILEY

摘要:

AbstractDonnan equilibria between solutions of various carbohydrates polyins and Na⊕have been measured by equilibrium dialysis. From the results, estimates have been made of the degree of Na⊕fixation by the polyions. Comparison is made between the behavior of the complex proteoglycan macromolecules and their constituent glycosaminoglycans. Attempts to interpret these results and the Na⊕activity in saltfree solutions on the parameter of the intercharge distance has been made. By use of studies on carboxymethylcellulose, the relative importance of the carboxyl and of the sulphate ester groups in the Na⊕fixation is assessed. The relevance of the measurements to the previously described diffusional effects found in real and model connective tissues is di

ISSN:0006-3525    

DOI:10.1002/bip.1972.360110811

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

年代:1972

数据来源: WILEY