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Observation of a new oxygen-isotope-sensitive Raman band for oxyhemoproteins and its implications in heme pocket structures

Journal Article · · Journal of the American Chemical Society; (United States)
DOI:https://doi.org/10.1021/ja00102a025· OSTI ID:6735947
; ;  [1];  [2]; ;  [3]
  1. Okazaki National Research Inst. (Japan) Graduate Univ. for Advanced Studies, Okazaki (Japan)
  2. Argonne National Lab., IL (United States)
  3. Himeji Inst. of Technology, Hyogo (Japan)

A new oxygen-isotope-sensitive Raman band was found for oxyhemoglobin (HbO[sub 2]) and oxycytochrome c oxidase (CcO[center dot]O[sub 2]) in the frequency region lower than the Fe-O[sub 2] stretching mode ([nu][sub Fe-O2]). This band was located at 425 cm[sup [minus]1] for Hb[sup 16]O[sub 2] and shifted to 405 cm[sup [minus]1] with Hb[sup 18]O[sub 2] and to approximately 423 and approximately 407 cm[sup [minus]1] with Hb[sup 16]O[sup 18]O. The corresponding band appeared at 435 cm[sup [minus]1] for CcO[center dot][sup 16]O[sub 2] and shifted to 415 cm[sup [minus]1] with CcO[center dot][sup 18]O[sub 2]. Accordingly, the band has been assigned to the Fe-O-O bending mode (delta[sub FeOO]). However, the corresponding band could not be identified for oxymyoglobin (MbO[sub 2]). The Fe-O[sub 2] stretching mode ([nu][sub Fe-O2]) was observed at 568, 567, 544, and 544 cm[sup [minus]1] for Hb[sup 16]O[sub 2], Hb[sup 16]O[sup 18]O, Hb[sup 18]O[sup 16]O, and Hb[sup 18]O[sub 2], respectively, and the corresponding modes were observed at 571, 569, 547, and 545 cm[sup [minus]1] for MbO[sub 2] and 571, 567, 548, and 544 cm[sup [minus]1] for CcO[center dot]O[sub 2]. The [nu][sub Fe-O(2)] bandwidths of HbO[sub 2] and MbO[sub 2] were alike and 1.5 times broader than that of CcO-O[sub 2], suggesting that the Fe-O-O geometry is more nearly fixed in the latter. 44 refs., 6 figs., 1 tab.

OSTI ID:
6735947
Journal Information:
Journal of the American Chemical Society; (United States), Journal Name: Journal of the American Chemical Society; (United States) Vol. 116:23; ISSN JACSAT; ISSN 0002-7863
Country of Publication:
United States
Language:
English