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About 6,230 papers for “polypeptide chains”

Interactions between Immunoglobulin Polypeptide Chains*

Takachika Azuma, Kozo Hamaguchi, Shunsuke Migita · 2016

1. The dimerization of reduced and alkylated Bence Jones proteins was studied by gel chromatography and circular dichroic (CD) measurements. The association con-stants of two type X proteins, as estimated by gel chromatography, were 105 and 2xlO6M~1 at pH 5.5, 25°C. The changes in the CD spectrum in the aromatic absorp-tion region with protein concentration and those with pH on the alkaline side indicate that the monomeric and dimeric forms of type X proteins are different from each other as regards the environment of tyrosyl residues. 2. The conformation of IgG molecules reconstituted from the alkylated H chain of a myeloma protein and various specimens of alkylated Bence Jones proteins was studied by CD measurements. The CD spectra of the recombinants were different depending on the specimens of L chains used, even if the antigenic type was the same. This indicates that the conformational change observed when H and L chains recombine is mainly associated with the conformational change of the variable portion of the L chain. i

Cited by 0

Fundamental dimensions of polypeptide chains

Robert B. Corey, Linus Pauling · Proceedings of the Royal Society of London. Series B, Biological sciences · 1953

Abstract The dimensions of the polypeptide chain and of its associated N—H•••O hydrogen bonds can be inferred with confidence. Data from many sources—X-ray diffraction analyses of crystals of organic acids, amides, peptides and related compounds; polarized infra-red studies of crystals—together with fundamental concepts of structural chemistry, now provide a basis for satisfactory knowledge and understanding of the dimensions and configurations of the amide group, C H / C'—N // C C The normal coplanarity of the atoms of this group is the result of resonance which gives rise to partial double-bond character of the N—C′ peptide bond. Rotation about this bond is, in general, severely restricted. The trans configuration of the amide group appears to be preferred. Interatomic distances and bond angles of the amide group which may be derived from the present data are: N—C = 1·47 Å C—N—C′ = 123° N—C′ = 1·32 C—N—H = 114 C′—O = 1·24 H—N—C′= 123 C′—C = 1·53 N—C′—O = 125 N—C′—C = 114 O—C′—C = 121 C′—C—N = 110 The dimensions and directional characteristics of N—H•••O hydrogen bonds have been determined in a great variety of crystals. In these crystals the N•••O distances vary, falling generally within the limits 2·79 ± 0·12 Ä. The H•••O vector rarely makes an angle greater than 20° with the probable direction of the N—H bond.

Cited by 259

Stable configurations of polypeptide chains

Linus Pauling, Robert B. Corey · Proceedings of the Royal Society of London. Series B, Biological sciences · 1953

Abstract Several configurations of polypeptide chains involving planar amide groups with the dimensions found by experiment for simple substances, and hydrogen bonds between the NH groups and the carbonyl oxygen atoms, have been discovered. One of these structures, the α-helix, with about 3·7 amino-acid residues per turn of the helix, has been assigned to synthetic polypeptides and proteins that give X-ray diagrams of the α-keratin type. The evidence supporting this assignment is reviewed. Other configurations of polypeptide chains, including they γ-helix, three pleated-sheet structures, and the three-chain helical structure proposed for collagen, are described, and evidence bearing on their possible presence in proteins is discussed.

Cited by 96

Optical anisotropy of polypeptide chains

R. T. Ingwall, Paul J. Flory · Biopolymers · 1972

Abstract Optical anisotropies γ 2 of N‐t‐butylacetamide (tBA), N ‐Methylacetamide (MA), and N, N‐dimethylacetamide (DMA) have been determined from the Rayleigh ratios for depolarzed scattering by dilute solutions of the amides in p‐dioxane. Traceless optical polarizability tensors \documentclass{article}\pagestyle{empty}\begin{document}$ \widehat{\rm \alpha } $\end{document} for the amides are derived from these results in conjunction with the Kerr constant for tBA determined by LeGèvre and co‐workers. It is shown that the tensor \documentclass{article}\pagestyle{empty}\begin{document}$ \widehat{\rm \alpha } $\end{document} i for the glycyle unit in a polypeptide chain may be identified with \documentclass{article}\pagestyle{empty}\begin{document}$ \widehat{\rm \alpha } $\end{document} MA . Methods for deriving corresponding tensors for other peptide units are indicated and the traceless polarizability tensor \documentclass{article}\pagestyle{empty}\begin{document}$ \widehat{\rm \alpha } $\end{document} for a polypeptide chain in any specified configuration is formulated.

Cited by 16

Heterogeneity of Rabbit Light-Polypeptide Chains

R A Reisfeld · Cold Spring Harbor Symposia on Quantitative Biology · 1967

Information concerning the heterogeneity of immunoglobulins, both as antigens and as antibodies, has been rapidly accumulating during the past years as has been discussed in detail in a number of recent reviews (Cohen and Porter, 1964; Nisonoff and Thorbecke, 1964; Fleischman, 1966). The electrophoretic heterogeneity of light polypeptide chains has been particularly well studied and described by many investigators. An example of a genetic control of heterogeneity of such molecules was provided by the discovery of allotypes (Oudin, 1956), the genetically controlled, antigenic forms of serum protein which differ among individuals within a species. We have carried out studies in order to understand the relationship between the genetic control of allotypic specificities and the structure and biosynthesis of rabbit γG-immunoglobins. We found chemical differences associated with allotypic specificities of light chains, such as distinct differences in amino acid composition and peptide maps, as well as a large degree of electrophoretic

Cited by 10

Polypeptide Chains Containing d-γ-Hydroxyvaline

Katarzyna Pisarewicz (2684293), David Mora (2684296), Fred C. Pflueger (2684290) et al. · Figshare · 2016

Life has an unexplained and distinct l-homochirality. Proteins typically incorporate only l-amino\nacids into their sequences. In the present study, d-Val and d-γ-hydroxyvaline (d-Hyv; <u>V</u>*) have been found\nwithin ribosomally expressed polypeptide chains. Four conopeptides were initially isolated, gld-<u>V</u>*/gld-<u>V</u>*‘\nfrom the venom of <i>Conus gladiator</i> and mus-<u>V</u>*/mus-<u>V</u>*‘ from the venom of <i>Conus</i> <i>mus</i>. Their complete\nsequences (gld-<u>V</u>*/gld-<u>V</u>*‘ = Ala-Hyp-Ala-Asn-Ser-d-Hyv-Trp-Ser and mus-<u>V</u>*/mus-<u>V</u>*‘ = Ser-Hyp-Ala-Asn-Ser-d-Hyv-Trp-Ser) were determined by a combination of nano/pico-NMR and MS/MS methods. The amino\nacid triad that contains the γ-hydroxylated residue, Ser-d-Hyv-Trp, is a novel structural motif that is stabilized\nby specific interactions between the d-amino acid and its neighboring l-counterparts. These interactions\ninhibit lactonization, a peptide backbone scission process that would normally be initiated by γ-hydroxylated\nresidues. Conopeptides possessing the Ser-d-Hyv-Trp motif have been termed γ-hydroxyconophans. We\nhave also isolated analogous conopeptides (gld-<u>V</u> and mus-<u>V</u>) containing d-Val instead of d-Hyv; these\nare termed conophans. γ-Hydroxyconophans and conophans are particularly atypical because (i) they are\nnot constrained as most conopeptides, (ii) they are extremely short in length, (iii) they have a high content\nof hydroxylated residues, and (iv) their sequences have no close match with other peptides in sequence\ndatabases. Their modifications appear to be part of a novel hyperhydroxylation mechanism found within\nthe venom of cone snails that enhances neuronal targeting. The finding of d-Val and d-Hyv within this\nfamily of peptides suggests the existence of a corresponding d-stereospecific enzyme capable of d-Val\noxidation.

Cited by 0Open access

Cluster distance geometry of polypeptide chains

Gordon M. Crippen · Journal of Computational Chemistry · 2004

Distance geometry has been a broadly useful tool for dealing with conformational calculations. Customarily each atom is represented as a point, constraints on the distances between some atoms are obtained from experimental or theoretical sources, and then a random sampling of conformations can be calculated that are consistent with the constraints. Although these methods can be applied to small proteins having on the order of 1000 atoms, for some purposes it is advantageous to view the problem at lower resolution. Here distance geometry is generalized to deal with distances between sets of points. In the end, much of the same techniques produce a sampling of different configurations of these sets of points subject to distance constraints, but now the radii of gyration of the different sets play an important role. A simple example is given of how the packing constraints for polypeptide chains combine with loose distance constraints to give good calculated protein conformers at a very low resolution.

Cited by 3Open access

Heterogeneity of Rabbit Light-Polypeptide Chains

A. Reisfeld · 2016

Information concerning the heterogeneity of immunoglobulins, both as antigens and as anti-bodies, has been rapidly accumulating during the past years as has been discussed in detail in a num-ber of recent reviews (Cohen and Porter, 1964; Nisonoff and Thorbecke, 1964; Fleischman, 1966). The electrophoretic heterogeneity of light poly-peptide chains has been particularly well studied and described by many investigators. An example of a genetic ontrol of heterogeneity of such mole-cules was provided by the discovery of allotypes (Oudin, 1956), the genetically controlled, antigenic forms of serum protein which differ among indi-viduals within a species. We have carried out studies in order to understand the relationship between the genetic ontrol of allotypic specificities and the structure and biosynthesis of rabbit ~,G-immunoglobins. Wefound chemical differences associated with allotypic specificities of light chains, such as distinct differences in amino acid composition and peptide maps, as well as a large degree of electrophoretic heterogeneity (Reisfeld,

Cited by 0

Cluster Distance Geometry of Polypeptide Chains

See Profile, Gordon M. Crippen · 2004

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Cited by 0

Noncovalent Interaction Between Immunoglobulin (Ig) Polypeptide Chains

Barry J. Zimmerman, Howard M. Grey · The Journal of Immunology · 1971

Abstract A number of studies have demonstrated the feasibility of recombining light and heavy chains from a variety of different sources to yield four chain molecules having a conformation indistinguishable from native molecules by several independent criteria. Thus, although competitive recombination experiments have demonstrated preferential reassociation of autologous chains (1–4), hybridization with heterologous light chains, including light chains derived from Igs of different mammalian species, was also readily accomplished (5). Other experiments have shown that the reconstitution of rabbit half molecules results in random hybridization of γ heavy chains creating heteroligating 7S antibody molecules (6) and hybrid H chain allotype pairings (7). The present investigation grew out of published data supporting the concept that during its antibody-secreting lifetime a single cell may be capable of “switching” the class of its antibody product from IgM to IgG (8, 9). This premise raised the possibility that during the period of “switching over” immunoglobulin “monsters” might be synthesized containing both µ and γ heavy chains. In this paper we have examined the products resulting from in vitro recombination of a mixture of heavy chains from myeloma proteins of two different heavy chain classes in the presence of a marked excess of normal light chains. The data indicate that heavy chains do not pair randomly across different Ig classes but instead, the 7S molecules that resulted from this procedure contained heavy chains which had segregated strictly according to class with little, if any, heavy chain hybridization occurring.

Cited by 4