Journal article
Microperoxidase 11: a model system for porphyrin networks and heme-protein interactions
Journal of biological inorganic chemistry, v 14(8), pp 1289-1300
Nov 2009
PMID: 19639347
Featured in Collection : UN Sustainable Development Goals @ Drexel
Abstract
We measured the circular dichroism (CD) and absorption spectra of the B-band region of microperoxidase 11 (MP11) as a function of temperature and peptide concentration. At micromolar concentrations, small MP11 dimers or trimers lead to excitonic coupling between low-spin and high-spin heme groups, to which the NH(2) group of the MP11 N-terminal and H(2)O are bound as a sixth ligand, respectively. These aggregates convert into monomers with hexacoordinated high-spin heme groups with increasing temperature. This transition can be described by a two-state model. Aggregation becomes more extended at 50 microM concentration and causes some B-band hyperchromism, which reflects a J-type arrangement of heme groups linked together in the aggregates formed. At near-millimolar concentration, the CD and absorption spectra of the B-band region suggest the existence of even more extended and thermally stable aggregates, which might involve mu-oxo dimers of the heme groups. The degree of aggregation at 50 and 500 microM concentration increases substantially if the sample is freed from most of its oxygen in a N(2) atmosphere. The CD spectrum of the monomeric high-spin species is reminiscent of that observed for the unfolded alkaline conformation of the intact protein. Finally, we investigated the binding of acetylmethionine (AcM) ligands to the heme at aggregation-supporting conditions (500 microM concentration). The data suggest that the ligand prevents any substantial aggregation. As a surprising result, our data reveal that AcM-MP11 complexes exhibit a high-spin/low-spin mixture, with the high-spin configuration being stabilized at high temperatures.
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Details
- Title
- Microperoxidase 11: a model system for porphyrin networks and heme-protein interactions
- Creators
- Daniel Verbaro - Department of Chemistry, Drexel University, Philadelphia, PA 19104, USAAndrew HagarmanAjay KohliReinhard Schweitzer-Stenner
- Publication Details
- Journal of biological inorganic chemistry, v 14(8), pp 1289-1300
- Publisher
- Springer Nature; Germany
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Chemistry
- Web of Science ID
- WOS:000271422100013
- Scopus ID
- 2-s2.0-70449527477
- Other Identifier
- 991014878206904721
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InCites Highlights
Data related to this publication, from InCites Benchmarking & Analytics tool:
- Web of Science research areas
- Biochemistry & Molecular Biology
- Chemistry, Inorganic & Nuclear