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Histidine-Tailed Microperoxidase-10: A pH-Dependent Ligand Switch

Cheek, Jennifer and Low, Donald W. and Gray, Harry B. and Dawson, John H. (1998) Histidine-Tailed Microperoxidase-10: A pH-Dependent Ligand Switch. Biochemical and Biophysical Research Communications, 253 (2). pp. 195-198. ISSN 0006-291X. doi:10.1006/bbrc.1998.9778.

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The electronic absorption and magnetic circular dichroism (MCD) spectra of ferric histidine-tailed microperoxidase-10 (His-MP10) change dramatically as the pH is raised from 1.8 to 11.8. Two distinct species are observed (pK_a= 4.4). The spectra of acidic ferric His-MP10 nearly match those of ferric mesoporphyrin-reconstituted myoglobin and so the axial ligands are assigned to be histidine and water. The retention of histidine ligation below pH 4 contrasts to the behavior of myoglobin and horseradish peroxidase which convert to five-coordinate water ligated and then lose the heme prosthetic group at even lower pH. Neutral and alkaline ferric His-MP10 have spectra that are very similar to those of the imidazole complex of ferric mesoporphyrin-reconstituted myoglobin. Thus, we conclude that it is bis-histidine ligated with the C-terminal histidine bound as the sixth ligand. Thus, ferric His-MP10 exhibits a pH-dependent ligand switch with a change in axial ligation from water and histidine at low pH to bis-histidine at neutral and alkaline pH.

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Gray, Harry B.0000-0002-7937-7876
Additional Information:© 1998 Academic Press. Received 6 November 1998. We thank Drs. Edmund W. Svastits and John J. Rux for assembling the MCD software and Alycen Pond for helpful discussions. Support for this study was provided by NIH Grant GM 26730 (J.H.D.) and NSF Grant CHE-9807150 (H.B.G.).
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Subject Keywords:peroxidase; magnetic circular dichroism spectroscopy; heme enzyme; myoglobin; histidine ligation.
Issue or Number:2
Record Number:CaltechAUTHORS:20170906-092356727
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Official Citation:Jennifer Cheek, Donald W. Low, Harry B. Gray, John H. Dawson, Histidine-Tailed Microperoxidase-10: A pH-Dependent Ligand Switch, Biochemical and Biophysical Research Communications, Volume 253, Issue 2, 1998, Pages 195-198, ISSN 0006-291X, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:81181
Deposited By: Ruth Sustaita
Deposited On:06 Sep 2017 17:17
Last Modified:15 Nov 2021 19:41

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