Amide transitions

In this laboratory we have examined the ORD of various membrane systems including heavy beef heart submitochondrial vesicles, rat liver submitochondrial vesicles, erythrocyte ghosts, and the membranes of Micrococcus lysodeikticus, Halobacterium halobium, Halobacterium cuti-rubrum, and Mycoplasma laidlawii. The optical behavior of all these materials is strikingly similar the Cotton effects are similar to those produced by an a-helix but are red shifted to abnormally high wavelengths (71). Cotton effects arising from amide transitions in other... 

In protein systems in particular, a distinction between intrinsic and extrinsic Cotton effects has been made 31). The intrinsic effects are the result of internal dissymmetric interactions of protein chromophores such as the amide transitions in helical arrays. Extrinsic effects relate to non-protein substances which are usually optically inactive but exhibit optical activity when conjugated to a protein or to an... 

The CD spectrum shows lack of any ellipticity band around 222 nm, a position where the characteristic n-71 amide transition in right-handed a-helices occurs (247). Furthermore, the overall CD spectrum of the HiPISP differs qualitatively, as well as quantitatively, from those of other non-heam iron-sulfur proteins. This is consistent with the Moss-bauer (253) and EPR (240) data that have indicated a different nature of the iron center in HiPISP relative to the ferredoxins and justifies, in part, the independent treatment we are giving these two classes of proteins. 

Carboxyl and Amide Transitions in the Circular Dichroism of Glycosaminoglycans... 

There seems to be a drastic change in the values of both n-TT and tt-TT amide transitions when the number of sugar units is ten or higher. It is evident from the plot of both the 210 nm band ellipticity and the ratio of... 

It has been demonstrated (5,Ul) that amide transition, at least in hyaluronic acid, is very sensitive to conformational change. The CD spectra hyaluronate in film, hyaluronic acid in aqueous-organic solvent, and Cu hyaluronate differ from those of acid and neutral forms of hyaluronatqf. In all three spectra the appearance of a stipng negative band in the r-ti amide transition and apparent loss of n-ir CD minima are evident, and the changes have been attributed to a conformational transition of the molecule to a -fold helix. 

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