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Tyrosine–heme ligation in heme–peptide complex: design based on conserved motif of catalase

Rai, Jagdish and Raghothama, S and Sahal, D (2007) Tyrosine–heme ligation in heme–peptide complex: design based on conserved motif of catalase. In: Journal of Peptide Science, 13 (6). pp. 406-412.

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On the basis of evolutionary conservation of sequence in catalases, we have designed a heme-binding peptide $(Ac-RLKSYTDTQISR^{12}-(GGGG)-CRIVHC^{22}-NH_2)$ for the 'redox activity modulation' of heme. Heme-binding studies showed a blueshifted Soret (369 nm) in the presence of TFE and a red-shifted Soret (418 nm) in the absence of TFE. These blue-and red-shifted Sorets suggest ligation through tyrosinate and histidine, respectively. This is the first designed peptide ligating to heme through tyrosine. NMR studies have confirmed that tyrosine ligation to heme in this heme-peptide complex occurs only in the presence of TFE. We suggest that TFE induces helicity in the peptide and brings the arginine and tyrosine in proximity, resulting in ionization of the phenolic side chain of tyrosine. In the absence of TFE, the unstructured peptide lacks the intra-molecular $Arg^+Tyr^-$ ion pair, allowing heme binding to histidine. This peptide has significant peroxidase activity though it does not have catalase activity.

Item Type: Journal Article
Publication: Journal of Peptide Science
Publisher: Wiley InterScience
Additional Information: Copyright of this article belogs to Wiley InterScience.
Keywords: catalyst;conserved motif;designed peptide;peptidomimetics; Soret band
Department/Centre: Division of Chemical Sciences > NMR Research Centre (Formerly Sophisticated Instruments Facility)
Date Deposited: 03 Jun 2008
Last Modified: 19 Sep 2010 04:45
URI: http://eprints.iisc.ac.in/id/eprint/14174

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