Chain rearrangement

There are indications which fall short of definite proof, that a certain amount of chain rearrangement takes place, thus reducing the real chain expansion to values less than expected from elementary models. 

Fig. 5. The effect of protein-protein interactions on Nephila edulis major ampullate circular dichroism spectra in solution. A change in secondary structure with increasing concentration is observed. At low concentration (minimal protein-protein interactions) silk proteins appear partially unfolded in solution. At higher concentration (higher protein-protein interactions) silk proteins refold into a helix-like structure, most likely a molten-like globule (from Dicko et al., 2004c). This final molten structure would facilitate local chain rearrangement while preserving the global structure for protein storage and transport. (Copyright 2004 American Chemical Society.)...

An example of main-chain rearrangement (i.e., in the backbone of the polymer) is depicted in Scheme 75 [225],... 

If 8L/L0 is small, as observed experimentally, perhaps due to very slow kinetics of chain rearrangements, then the relationship between Lq and Tc is the same as the Gibbs-Thompson equation ... 

Raaphorst, F.M., Timmers, E., Renter, M.J.H., et al. (1992). Restricted utilization of germline VH3 genes and short diverse third complementarity-determining regions (CDR3) in human fetal B-lymphocyte immunoglobulin heavy chain rearrangements. Eur. J. Immunol., 22, 247-251. 

Transalkylation and Dealkylation. In addition to isomerizations (side-chain rearrangement and positional isomerization), transalkylation (disproportionation) [Eq. (5.56)] and dealkylation [Eq. (5.57)] are side reactions during Friedel-Crafts alkylation however, they can be brought about as significant selective hydrocarbon transformations under appropriate conditions. Transalkylation (disproportionation) is of great practical importance in the manufacture of benzene and xylenes (see Section 5.5.4) ... 

A similar proposal was subsequently advanced for heavy chain rearrangements (Altet al., 1981) synthesis of a functional heavy chain in someway signals the cell to cease further V(D)J rearrangement. An alternate explanation for the presence in a B cell of no more than one heavy chain, proposed by Wabl and Steinberg (1982),... 

Grawunder, U., Leu, T.M.J., Schatz, D.G., Werner, A., Rolink, A.G., Melchers, E, Winkler, T.H. (1995). Down-regulation of RAG1 and RAG2 gene expression in PreB cells after functional immunoglobulin heavy chain rearrangement. Immunity 3,601-608. 

A tentative conclusion from these considerations is, therefore, that the rate-determining factor for the second stage sorption is the rate at which polymer chains rearrange themselves in the presence of penetrant molecules. In this connection, we may remark that work is in progress concerning the correlation between and the mean relaxation time of a glassy polymer-diluent system (Odani, unpublished). 

Coenzyme Bij-Dependent Mutases Causing Carbon Chain Rearrangements... 

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