4MBA

APLYSIA LIMACINA MYOGLOBIN. CRYSTALLOGRAPHIC ANALYSIS AT 1.6 ANGSTROMS RESOLUTION

Summary for 4MBA

• Entry DOI: 10.2210/pdb4mba/pdb
• Descriptor: MYOGLOBIN, PROTOPORPHYRIN IX CONTAINING FE, IMIDAZOLE, ... (4 entities in total)
• Functional Keywords: oxygen storage
• Biological source: Aplysia limacina (slug sea hare)
• Total number of polymer chains: 1
• Total formula weight: 16035.01

Authors

Bolognesi, M.,Onesti, S.,Gatti, G.,Coda, A.,Ascenzi, P.,Brunori, M. (deposition date: 1989-02-22, release date: 1990-01-15, Last modification date: 2024-10-23)

Primary citation

Bolognesi, M.,Onesti, S.,Gatti, G.,Coda, A.,Ascenzi, P.,Brunori, M.
Aplysia limacina myoglobin. Crystallographic analysis at 1.6 A resolution.
J.Mol.Biol., 205:529-544, 1989

PubMed Abstract: The crystal structure of the ferric form of myoglobin from the mollusc Aplysia limacina has been refined at 1.6 A resolution, by restrained crystallographic refinement methods. The crystallographic R-factor is 0.19. The tertiary structure of the molecule conforms to the common globin fold, consisting of eight alpha-helices. The N-terminal helix A and helix G deviate significantly from linearity. The distal residue is recognized as Val63 (E7), which, however, does not contact the heme directly. Moreover the sixth (distal) co-ordination position of heme iron is not occupied by a water molecule at neutrality, i.e. below the acid-alkaline transition point of A. limacina myoglobin. The heme group sits in its crevice in the conventional orientation and no signs of heme isomerism are evident. The iron atom is 0.26 A out of the porphyrin plane, with a mean Fe-N (porphyrin) distance of 2.01 A. The co-ordination bond to the proximal histidine has a length of 2.05 A, and forms an angle of 4 degrees with the heme normal. A plane containing the imidazole ring of the proximal His intersects the heme at an angle of 29 degrees with the (porphyrin) 4N-2N direction. Inspection of the structure of pH 9.0 indicates that a hydroxyl ion is bound to the Fe sixth co-ordination position.

PubMed: 2926816
DOI: 10.1016/0022-2836(89)90224-6

Experimental method

X-RAY DIFFRACTION (2 Å)