摘要:

AbstractThe Zimm‐Bragg theory is extended to treat the melting of the triple helix poly (A + 2U) for a solution with a 1 : 2 mole ratio of poly A to poly U. Only the case for long chains is considered. For a given set of parameters the theory predicts the fraction of segments in the triple helix, double helix, and random coil states as a function of temperature.Four nucleation parameters are introduced to describe the two order–disorder transitions (poly (A + 2U) ⇄ poly A + 2 poly U and poly (A + U) ⇄ poly A + poly U) and the single order–order transition (poly (A + 2U) ⇄ poly (A + U) + poly U). A relation between the nucleation parameters is obtained which reduces the number of independent parameters to three. A method for determining these parameters from experiment is presented. From the previously published data of Blake, Massoulié and Fresco8for [Na+] = 0.04, we find σT= 6.0 × 10−4, σD= 1.0 × 10−3, and σσ* = 1.5 × 10−3. σTand σDare the nucleation parameters for nucleating a triple helix and double helix, respectively, from a random coil region. σσ* is the nucleation parameter for nucleating a triple helix from a double helix and a single strand.Melting curves are generated from the theory and compared with th

ISSN:0006-3525    

DOI:10.1002/bip.1973.360120302

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe general strategy for the synthesis by conventional procedure of N‐ and C‐terminal fragments and of the entire sequence of baker's yeast iso‐1‐cytochrome c is discussed. The synthesis of theN‐benzyloxycarbonylhexadecapeptidetert‐butoxycarbonylhydrazide corresponding to the sequence 1–16 of the apoprotein is descri

ISSN:0006-3525    

DOI:10.1002/bip.1973.360120303

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

年代:1973

数据来源: WILEY

摘要:

AbstractSynthesis is described for theN‐o‐nitrophenylsulfenylheptapeptidetert‐butoxycarbonylhydrazide corresponding to positions 17–23 of the amino acid sequence of baker's yeast iso‐1‐cytochrome c. Moreover a new method of selective removal of theS‐acetamidomethyl group for analytical and preparative purpos

ISSN:0006-3525    

DOI:10.1002/bip.1973.360120304

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

年代:1973

数据来源: WILEY

摘要:

AbstractSyntheses are described for twoN‐benzyloxycarbonylpeptidetert‐butoxycarbonylhydrazides which correspond to positions 24–34 and 35–44, respectively, of the primary structure of baker's yeast iso‐1‐cytochrome c. The two peptide derivatives were coupled via the azide procedure to form theN‐benzyloxycarbonylheneicosapeptidetert‐butoxycarbonylhydrazide (

ISSN:0006-3525    

DOI:10.1002/bip.1973.360120305

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe synthesis is described for theN‐benzyloxycarbonyldodecapeptidetert‐butoxycarbonylhydrazide corresponding to the sequence 45–56 of baker's yeast iso‐1‐cytochrome c by fragment condensation using the Rudinger modified azide procedure for the assembly of the small

ISSN:0006-3525    

DOI:10.1002/bip.1973.360120306

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

年代:1973

数据来源: WILEY

摘要:

AbstractPronase E is able to hydrolyze poly‐L‐lysine in 100% yield into the monomerL‐lysine. The experiments show an intermediate production of tri‐L‐lysine and di‐L‐lysine that are clipped off from the polymeric peptide. During the hydrolytic process a number of characteristic amino acids are released from the enzyme that may indicate its activation. Amino acids as well as mono‐L‐lysine are decomposed by pronase E after a perio

ISSN:0006-3525    

DOI:10.1002/bip.1973.360120307

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe interactions between chondroitin‐6‐sulfate (chondroitin sulfate C) and poly‐L‐lysine have been studied as models for investigation of possible complex formation between fibrous proteins and mucopolysaccharides. Results obtained using circular dichroism spectroscopy show that poly‐L‐lysine adopts the α‐helical conformation in dilute aqueous salt solution at pH 7 when mixed with chondroitin‐6‐sulfate, rather than the “charged‐coil” observed in the absence of this mucopolysaccharide. This conformation‐directing interaction is at a maximum when the ratio of lysine to disaccharide residues is 1 : 1. Changes in the CD spectrum of a 1 : 1 mixture following increase in the salt concentration, or addition of non‐polar solvents, indicate that the interaction is ionic in nature. No such effects are observed for non‐sulfated mucopolysaccharides mixed with poly‐L‐lysine, suggesting that, for chondroitin‐6‐sulfate, it is the sulfate groups rather than the carboxyls which interact with the amine groups of the polypeptide.Elevation of the temperature leads to disruption of the interactions between the polypeptide and polysaccharide species. A sharp melting transition occurs at 47.0 ± 1.0°C, when the poly‐L‐lysine reverts to the “charged‐coil” conformation. The sharp transition suggests that regular ionic bonds are formed between the polypeptide and polysaccharide. These results suggest that a conformation‐directing interaction may occur between sulfated mucopolysaccharides and the

ISSN:0006-3525    

DOI:10.1002/bip.1973.360120308

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

年代:1973

数据来源: WILEY

摘要:

AbstractThe electrostatic potential of an infinitely long cylinder with a periodic, discrete charge density was calculated, assuming the cylinder was immersed in a simple 1 : 1 electrolyte solution. The charge density of the simple electrolyte was taken to be the linearized Debye‐Hückel charge density. It was also assumed that the discrete charge density, was within the cylinder (rather than on its surface), and that the interior of the cylinder had a unique dielectric constantDh, which was treated as a parameter. Although this model (except for the Debye‐Hückel assumption) more realistically represents DNA than previous models, the calculated potential was found to be ambiguous, depending on the value chosen for the depth of the discrete charge below the cylinder surface. However it was also found that the dependence of the potential on the simple electrolyte concentration was well‐defined and was identical to that of a continuously charged cylinder. It was concluded that the continuously charged cylinder model adequately describes differential salt

ISSN:0006-3525    

DOI:10.1002/bip.1973.360120309

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

年代:1973

数据来源: WILEY

摘要:

AbstractBy analyzing the effect of urea and guanidine hydrochloride on the circular dichroism of many polypeptides and proteins, it is concluded that under conditions of high concentration of the perturbant and at low temperatures the resultant state approached is that of a local extended helix structure instead of a completely random coil. Intensification by urea and guanidine hydrochloride of the circular dichroism bands of poly‐L‐proline II leads to the proof that the mechanism of interaction of urea and guanidine hydrochloride with proteins is through hydrogen bonding to the backbone carbonyl gr

ISSN:0006-3525    

DOI:10.1002/bip.1973.360120310

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

年代:1973

数据来源: WILEY

摘要:

AbstractVacuum ultraviolet spectra are reported for a series of poly‐α‐amino acids which were film cast onto lithium fluoride discs. The solvents used for film casting were chosen such that chain conformations representative of those normally found for polypeptides were produced. Comparison of the spectra obtained suggests that the peptide group has at least one conformationally sensitive transition in the vacuum ultraviolet region at ∼165 nm. For the β, or extended, form of the polymers, the intensity of this transition appears to be greater than that found for the monomer units, whereas the formation of a more compact helix results in a reduction in the intensity of this transition relative to that found for the m

ISSN:0006-3525    

DOI:10.1002/bip.1973.360120311

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

年代:1973

数据来源: WILEY