SynopsisVibrational circular dichroism (VCD) spectra for the principal amide stretching vibrations, amide A (N-H stretch) and amide I (predominantly C=O stretch), are presented and analzyed for a variety of polypeptides dissolved in chloroform, as well as for two examples in DzO. Our results for poly(y-benzyl-L-glutamate) confirm the first and only previous report of VCD in polypeptides carried out by Singh and Keiderling [( ) Biopolymers 20,237-2401. Collectively, our spectra show that, the sense of the hisignate VCD in these two regions depends on the sense of a-helicity and not on the absolute configuration of the constituent amino acids. This conclusion is established by obtaining VCD for the two polypeptides, poly(P-benzyl-L-asparate) and poly(im-henzyl-L-histidine), that form left-handed as opposed to right-handed a-helices. A new amide band having significant VCD intensity owing to its Fermi resonance interaction with the N-H stretching mode has been identified as a weak shoulder on the low-frequency side of the amide A band near 3200 cm-' and is assigned as a combination hand of the amide I and amide I1 vibrations. VCD spectra of polypeptides in DzO solution, although weak, have been successfully measured in the amide I region, where spectra appear to he more complicated due to the presence of solvated and internally hydrogen-honded amide groups.Strong monosignate contributions to the VCD in the amide A and amide I regions for some of the polypeptides indicate coupling of an electronic nature between these two regions and is deduced by an application of the concept of local sum rules of rotational strength. It appears that a detailed understanding of the VCD obtained for polypeptides will not only be diagnostic of secondary structure, but also of more subtle structural and vibrational effects that give rise to local, intrinsic chirality in the amide vibrations.
The Indian diaspora has grown apace in the past three decades to comprise more than 20 million people spread over all continents. Although that figure is small compared to the more than a billion inhabitants in the homeland, it has reached a critical mass in various host countries. It has developed institutions, orientations and patterns of living specific to the institutional structures and socio-political contexts of the different hostlands. These patterns have been marked not only by the influences of the hostland culture but also by relations with the homeland. All the papers in this issue show two things: that the consciousness of homeland is never completely missing, and that the transnational context is part and parcel of diaspora and, indeed, implicit in its very definition. In other words, those who argue, like Gilroy, that diaspora is merely ''where it's at'', are wrong; but so are those, like Glick-Schiller, who substitute diaspora with transnational relations.This special issue is of interest because it studies the Indian diaspora from the ground up. Several of the papers are based on personal interviews in selected American cities. They explore problems encountered in attempts at negotiating an identity that is a balance of ''Americanness'' and ''Indianness''. In so doing, the papers address themselves to questions frequently posed in connection with diasporas worldwide: how are diasporas formed? How do their members relate to their hostland, and how do they resolve the tension between the need to adjust to their new surroundings and the need to preserve their cultural identities? What roles do
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