1NZ3

K45E-K63E Variant of Horse Heart Myoglobin

Summary for 1NZ3

• Entry DOI: 10.2210/pdb1nz3/pdb
• Related: 1NZ2 1NZ4 1NZ5 1WLA
• Descriptor: Myoglobin, PROTOPORPHYRIN IX CONTAINING FE (3 entities in total)
• Functional Keywords: horse heart myoglobin, oxygen storage-transport complex, oxygen storage/transport
• Biological source: Equus caballus (horse)
• Total number of polymer chains: 1
• Total formula weight: 17599.87

Authors

Hunter, C.L.,Maurus, R.,Mauk, M.R.,Lee, H.,Raven, E.L.,Tong, H.,Nguyen, N.,Smith, S.,Brayer, G.D.,Mauk, A.G. (deposition date: 2003-02-15, release date: 2003-04-08, Last modification date: 2023-08-16)

Primary citation

Hunter, C.L.,Maurus, R.,Mauk, M.R.,Lee, H.,Raven, E.L.,Tong, H.,Nguyen, N.,Smith, S.,Brayer, G.D.,Mauk, A.G.
Introduction and characterization of a functionally linked metal ion binding site at the exposed heme edge of myoglobin
Proc.Natl.Acad.Sci.USA, 100:3647-3652, 2003

PubMed Abstract: A binding site for metal ions has been created on the surface of horse heart myoglobin (Mb) near the heme 6-propionate group by replacing K45 and K63 with glutamyl residues. One-dimensional (1)H NMR spectroscopy indicates that Mn(2+) binds in the vicinity of the heme 6-propionate as anticipated, and potentiometric titrations establish that the affinity of the new site for Mn(2+) is 1.28(4) x 10(4) M(-1) (pH 6.96, ionic strength I = 17.2 microM, 25 degrees C). In addition, these substitutions lower the reduction potential of the protein and increase the pK(a) for the water molecule coordinated to the heme iron of metmyoglobin. The peroxidase [2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonic acid), ABTS, as substrate] and the Mn(2+)-peroxidase activity of the variant are both increased approximately 3-fold. In contrast to wild-type Mb, both the affinity for azide and the midpoint potential of the variant are significantly influenced by the addition of Mn(2+). The structure of the variant has been determined by x-ray crystallography to define the coordination environment of bound Mn(2+) and Cd(2+). Although slight differences are observed between the geometry of the binding of the two metal ions, both are hexacoordinate, and neither involves coordination by E63.

PubMed: 12644706
DOI: 10.1073/pnas.0636702100

Experimental method

X-RAY DIFFRACTION (1.6 Å)