1LUE

RECOMBINANT SPERM WHALE MYOGLOBIN H64D/V68A/D122N MUTANT (MET)

Summary for 1LUE

• Entry DOI: 10.2210/pdb1lue/pdb
• Descriptor: Myoglobin, SULFATE ION, PROTOPORPHYRIN IX CONTAINING FE, ... (4 entities in total)
• Functional Keywords: myoglobin, enzyme, sulfoxidation, oxygen storage-transport complex, oxygen storage/transport
• Biological source: Physeter catodon (sperm whale)
• Total number of polymer chains: 1
• Total formula weight: 18026.60

Authors

Phillips Jr., G.N. (deposition date: 2002-05-22, release date: 2003-11-04, Last modification date: 2024-02-14)

Primary citation

Yang, H.J.,Matsui, T.,Ozaki, S.,Kato, S.,Ueno, T.,Phillips Jr., G.N.,Fukuzumi, S.,Watanabe, Y.
Molecular engineering of myoglobin: influence of residue 68 on the rate and the enantioselectivity of oxidation reactions catalyzed by H64D/V68X myoglobin
Biochemistry, 42:10174-10181, 2003

PubMed Abstract: In the elucidation of structural requirements of heme vicinity for hydrogen peroxide activation, we found that the replacement of His-64 of myoglobin (Mb) with a negatively charged aspartate residue enhanced peroxidase and peroxygenase activities by 78- and 580-fold, respectively. Since residue 68 is known to influence the ligation of small molecules to the heme iron, we constructed H64D/V68X Mb bearing Ala, Ser, Leu, Ile, and Phe at position 68 to improve the oxidation activity. The Val-68 to Leu mutation of H64D Mb accelerates the reaction with H(2)O(2) to form a catalytic species, called compound I, and improves the one-electron oxidation of 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) (i.e., peroxidase activity) approximately 2-fold. On the other hand, H64D/V68I Mb oxygenates thioanisole 2.7- and 1600-fold faster than H64D and wild-type Mb, respectively. In terms of the enantioselectivity, H64D/V68A and H64D/V68S Mb were good chiral catalysts for thioanisole oxidation and produced the (R)-sulfoxide dominantly with 84% and 88% ee, respectively [Kato, S., et al. (2002) J. Am. Chem. Soc. 124, 8506-8507]. On the contrary, the substitution of Val-68 in H64D Mb with an isoleucine residue alters the dominant sulfoxide product from the (R)- to the (S)-isomer. The crystal structures of H64D/V68A and H64D/V68S Mb elucidated in this study do not clearly indicate residues interacting with thioanisole. However, comparison of the active site structures provides the basis to interpret the changes in oxidation activity: (1) direct steric interactions between residue 68 and substrates (i.e., H(2)O(2), ABTS, thioanisole) and (2) the polar interactions between tightly hydrogen-bonded water molecules and substrates.

PubMed: 12939145
DOI: 10.1021/bi034605u

Experimental method

X-RAY DIFFRACTION (1.7 Å)