PDBsum entry 1myh

Oxygen storage

PDB id: 1myh

Contents

Protein chains

153 a.a. *

Ligands

SO4 ×2

HEM ×2

Waters ×96

* Residue conservation analysis

PDB id:

1myh

Name:

Oxygen storage

Title:

High resolution x-ray structures of pig metmyoglobin and two cd3 mutants mb(lys45-> arg) and mb(lys45-> ser)

Structure:

Myoglobin. Chain: a, b. Engineered: yes

Source:

Sus scrofa. Pig. Organism_taxid: 9823

Resolution:

1.90Å R-factor: 0.227

Authors:

S.J.Smerdon,T.J.Oldfield,A.J.Wilkinson,Z.Dauter,K.Petratos,K.S.Wilson

Key ref:

T.J.Oldfield et al. (1992). High-resolution X-ray structures of pig metmyoglobin and two CD3 mutants: Mb(Lys45----Arg) and Mb(Lys45----Ser). Biochemistry, 31, 8732-8739. PubMed id: 1390659 DOI: 10.1021/bi00152a008

Date:

27-Feb-92 Release date: 31-Jan-94

Protein chains

P02189  (MYG_PIG) -  Myoglobin from Sus scrofa

Seq: 154 a.a.

Struc: 153 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

Enzyme reactions

• Enzyme class: E.C.?

DOI no: 10.1021/bi00152a008

Biochemistry 31:8732-8739 (1992)

PubMed id: 1390659

High-resolution X-ray structures of pig metmyoglobin and two CD3 mutants: Mb(Lys45----Arg) and Mb(Lys45----Ser).

T.J.Oldfield, S.J.Smerdon, Z.Dauter, K.Petratos, K.S.Wilson, A.J.Wilkinson.

ABSTRACT

The structure of pig aquometmyoglobin has been refined to a crystallographic R-factor of 19.8% against X-ray diffraction data between 10- and 1.75-A spacing. The final structural model comprises two molecules of pig myoglobin, 233 water molecules, and two sulfate ions. A water molecule is coordinated to each of the heme iron atoms with an average Fe-OH2 bond distance of 2.19 A, and the mean Fe-N epsilon (proximal histidine-93) distance is 2.20 A. In contrast to the structure of sperm whale metmyoglobin, the iron is not significantly displaced from the plane of the heme. At the entrance to the heme pocket, the side-chain amino group of lysine-45 (CD3) is well-defined in the electron density map and forms salt-bridging interactions with the heme 6-propionate and with a sulfate ion. Serine and arginine replacements have been made previously at position 45 to examine the proposal that the CD3 side chain acts as a barrier to ligand entry into the protein. Crystal structures of the arginine-45 and serine-45 mutant metmyoglobins have been solved to 1.9 and 2.0 A resolution, respectively. In both cases the structural changes are confined to the site of mutation. Arginine-45 takes up a conformation closely similar to that observed for this residue in wild-type sperm whale myoglobin, in which it makes more extensive charge-charge and charge-dipole interactions and appears to restrict the movement of the distal histidine away from the ligand. The hydroxyl group of serine-45 is disordered, but it is clear that the effect of the mutation is to open up the solvent-exposed face of the heme pocket.