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Biochemistry. 1997 Jun 10;36(23):7044-9.

Structures of wild-type chloromet and L103N hydroxomet Themiste zostericola myohemerythrins at 1.8 A resolution.

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1
Department of Chemistry, University of Utah, Salt Lake City 84112, USA.

Abstract

Myohemerythrin (Mhr) is a nonheme iron oxygen carrier found in the retractor muscles of marine "peanut" worms. The X-ray crystal structures of two recombinant Themiste zostericola Mhrs are reported to a resolution of 1.8 A. Surprisingly, the met wild-type structure (R = 17.8%) was found to contain chloride bound to Fe2, while coordinated hydroxide was found in the met L103N structure (R = 18.3%). An internal water molecule was also found distal to the Fe-O-Fe center of the mutant protein, forming hydrogen bonds with the coordinated hydroxide and the OD1 atom of Asn-103. This finding is consistent with the kinetic and spectroscopic results reported for the L103N mutant Mhr [Raner, G. M., Martins, L. J., & Ellis, W. R., Jr. (1997) Biochemistry 36, 7037-7043]. Possible roles for the side chain of residue 103 (Leu in wild-type Mhr) in gating ligand binding are also discussed.

PMID:
9188702
DOI:
10.1021/bi9630422
[Indexed for MEDLINE]

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