Characterization of Heme Orientational Disorder in a Myoglobin Reconstituted with a Trifluoromethyl-Group-Substituted Heme Cofactor

Yuki Kanai, Ayaka Harada, Tomokazu Shibata, Ryu Nishimura, Kosuke Namiki, Miho Watanabe, Shunpei Nakamura, Fumiaki Yumoto, Toshiya Senda, Akihiro Suzuki, Saburo Neya, Yasuhiko Yamamoto

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

The orientation of a CF3-substituted heme in sperm whale myoglobin and L29F, H64L, L29F/H64Q, and H64Q variant proteins has been investigated using 19F NMR spectroscopy to elucidate structural factors responsible for the thermodynamic stability of the heme orientational disorder, i.e., the presence of two heme orientations differing by a 180° rotation about the 5-15 meso axis, with respect to the protein moiety. Crystal structure of the met-aquo form of the wild-type myoglobin reconstituted with 13,17-bis(2-carboxylatoethyl)-3,8-diethyl-2,12,18-trimethyl-7-trifluoromethylporphyrinatoiron(III), determined at resolution of 1.25 Å, revealed the presence of the heme orientational disorder. Alterations of the salt bridge between the heme 13-propionate and Arg45(CD3) side chains due to the mutations resulted in equilibrium constants of the heme orientational disorder ranging between 0.42 and 1.4. Thus, the heme orientational disorder is affected by the salt bridge associated with the heme 13-propionate side chain, confirming the importance of the salt bridge in the heme binding to the protein.

Original languageEnglish
Pages (from-to)4500-4508
Number of pages9
JournalBiochemistry
Volume56
Issue number34
DOIs
Publication statusPublished - 2017 Aug 29
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry

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