X-ray absorption spectroscopic investigation of Fe(II)-peplomycin and peplomycin derivatives: the effect of axial ligation on Fe-pyrimidine back-bonding

  • Erik C. Wasinger
  • Kelly Zaleski
  • Britt Hedman
  • Keith O. Hodgson
  • Edward I. Solomon
Original Article

Abstract.

X-ray absorption spectroscopy (XAS) is used to study ferrous complexes of a bleomycin (BLM) congener, peplomycin (PEP), and two of its derivatives, iso-peplomycin (ISO) and depyruvamide peplomycin (DP), in which potential axial ligands have been perturbed and removed, respectively. Application of extended X-ray absorption fine structure analysis shows an elongation of the short-distance component of the first coordination sphere in DP and ISO relative to PEP. The XAS pre-edge intensity concomitantly decreases with increased axial perturbation. The short-distance component of PEP is correlated to the Fe-pyrimidine bond and is related to the amount of π-back-bonding. Thus, the XAS analysis of these complexes provides structural information relevant to their differences in O2 reactivity.

Bleomycin Peplomycin Back-bonding XAS 

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Copyright information

© SBIC 2001

Authors and Affiliations

  • Erik C. Wasinger
    • 1
  • Kelly Zaleski
    • 1
  • Britt Hedman
    • 2
  • Keith O. Hodgson
    • 2
  • Edward I. Solomon
    • 1
  1. 1.Department of Chemistry, Stanford University, Stanford, California 94305USA
  2. 2.Department of Chemistry, Stanford University and Stanford Synchrotron Radiation Laboratory, SLAC, Stanford University, Stanford, California 94309USA

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