A circularly permuted myoglobin possesses a folded structure and ligand binding similar to those of the wild-type protein but with a reduced thermodynamic stability.
A circular permutein of sperm whale myoglobin in which the G helix is C-terminal, the H helix is N-terminal, and 16 amino acids link the H helix to the A helix has been expressed in Escherichia coli. The permutein sequence begins with Gly121 (using the numbering scheme for the wild-type protein) and terminates with Pro120. The ligand binding function of the permutein was assayed using stopped-flow methods and shown to be essentially identical to that of the wild-type protein. In addition, one- and two-dimensional NMR studies of the cyanomet isoform of the permutein show a nativelike structure with a heme binding pocket very similar to that of the wild-type myoglobin. Although the structure and function of the permutein resemble those of the wild-type myoglobin, the permutein is less stable to chemical denaturation by 5.2 kcal/mol.
Fishburn
Anna L
AL
Department of Chemistry, Western Washington University, Bellingham, Washington 98225-9150, USA.
Keeffe
Jennifer R
JR
Lissounov
Alexei V
AV
Peyton
David H
DH
Anthony-Cahill
Spencer J
SJ
D000595:Amino Acid Sequence; D000818:Animals; D002942:Circular Dichroism; D004926:Escherichia coli / Q000235:genetics; D008024:Ligands; D008969:Molecular Sequence Data; D009211:Myoglobin / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding / Q000235:genetics; D011489:Protein Denaturation; D015202:Protein Engineering / Q000379:methods; D017510:Protein Folding; D017433:Protein Structure, Secondary / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification; D013816:Thermodynamics; D014508:Urea; D014907:Whales
D008024:Ligands; D009211:Myoglobin; D011994:Recombinant Proteins; D014508:Urea