Distinct Structural and Redox Properties of the Heme Active Site in Bacterial Dye Decolorizing Peroxidase-Type Peroxidases from Two Subfamilies: Resonance Raman and Electrochemical Study

SEZER M., Santos A., Kielb P., Pinto T., Martins L. O., Todorovic S.

BIOCHEMISTRY, vol.52, no.18, pp.3074-3084, 2013 (SCI-Expanded) identifier

  • Publication Type: Article / Article
  • Volume: 52 Issue: 18
  • Publication Date: 2013
  • Doi Number: 10.1021/bi301630a
  • Journal Name: BIOCHEMISTRY
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.3074-3084
  • Istanbul University Affiliated: Yes

Abstract

Spectroscopic data of dye decolorizing peroxidases (DyPs) from Bacillus subtilis (BsDyP), an A subfamily member, and Pseudomonas putida (PpDyP), a B subfamily enzyme, reveal distinct heme coordination patterns of the respective active sites. In solution, both enzymes show a heterogeneous spin population, with the six-coordinated low-spin state being the most populated in the former and the five-coordinated quantum mechanically mixed-spin state in the latter. We ascribe the poor catalytic activity of BsDyP to the presence of a catalytically incompetent six-coordinated low-spin population. The spin populations of the two DyPs are sensitively dependent on the pH, temperature, and physical, i.e., solution versus crystal versus immobilized, state of the enzymes. We observe a redox potential for the Fe2+/Fe3+ couple in BsDyP (-40 mV) at pH 7.6 substantially more positive than those reported for the majority of other peroxidases, including PpDyP (-260 mV). Furthermore, we evaluate the potential of the studied enzymes for biotechnological applications on the basis of electrochemical and spectroelectrochemical data.