The Structure of a Functional Unit from the Wall of a Gastropod Hemocyanin Offers a Possible Mechanism for Cooperativity
| Autor: | Eckhart W. Guthöhrlein, Wolfgang Voelter, Stanka Stoeva, Nicolay Genov, Wojciech Rypniewski, Krassimira Idakieva, Markus Perbandt, Christian Betzel |
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| Rok vydání: | 2003 |
| Předmět: |
Models
Molecular Glycosylation Protein Conformation medicine.medical_treatment Molecular Sequence Data Cooperativity Crystal structure Biology Crystallography X-Ray Models Biological Biochemistry Structure-Activity Relationship Rapana thomasiana Hemolymph medicine Animals Molecule Amino Acid Sequence Molecular interactions Binding Sites Sequence Homology Amino Acid Hemocyanin Protein Structure Tertiary Oxygen Crystallography Mollusca Hemocyanins Molecular mechanism Dimerization Protein Binding |
| Zdroj: | Biochemistry. 42:6341-6346 |
| ISSN: | 1520-4995 0006-2960 |
| Popis: | Structure-function relationships in a molluscan hemocyanin have been investigated by determining the crystal structure of the Rapana thomasiana (gastropod) hemocyanin functional unit RtH2e in deoxygenated form at 3.38 A resolution. This is the first X-ray structure of an unit from the wall of the molluscan hemocyanin cylinder. The crystal structure of RtH2e demonstrates molecular self-assembly of six identical molecules forming a regular hexameric cylinder. This suggests how the functional units are ordered in the wall of the native molluscan hemocyanins. The molecular arrangement is stabilized by specific protomer-to-protomer interactions, which are probably typical for the functional units building the wall of the cylinders. A molecular mechanism for cooperative dioxygen binding in molluscan hemocyanins is proposed on the basis of the molecular interactions between the protomers. In particular, the deoxygenated RtH2e structure reveals a tunnel leading from two opposite sides of the molecule to the active site. The tunnel represents a possible entrance pathway for dioxygen molecules. No such tunnels have been observed in the crystal structure of the oxy-Odg, a functional unit from the Octopus dofleini (cephalopod) hemocyanin in oxygenated form. |
| Databáze: | OpenAIRE |
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