Structure of hemocyanin subunit CaeSS2 of the crustacean Mediterranean crab Carcinus aestuarii
| Autor: | Jozef Van Beeumen, Stefan Stevanovic, Wolfgang Voelter, Rumyana Hristova, Ulrich Weser, Paolo Di Muro, Benedetto Salvato, Alexandar Dolashki, Savvas N. Savvides, Bart Devreese, Pavlina Dolashka-Angelova |
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| Rok vydání: | 2005 |
| Předmět: |
Models
Molecular Glycosylation Stereochemistry Protein subunit medicine.medical_treatment Molecular Sequence Data Biochemistry Protein Structure Secondary chemistry.chemical_compound Crustacea medicine Animals Amino Acid Sequence Molecular Biology Quenching (fluorescence) Binding Sites biology Molecular Structure Ecology Protein primary structure Oxygen transport Active site Hemocyanin General Medicine biology.organism_classification Protein Structure Tertiary Carcinus aestuarii Protein Subunits chemistry Hemocyanins biology.protein Peptides Sequence Alignment Copper |
| Zdroj: | Journal of biochemistry. 138(3) |
| ISSN: | 0021-924X |
| Popis: | Arthropodan hemocyanins are giant respiratory proteins responsible for oxygen transport. They exhibit unusual assemblies of up to 48 structural subunits. Hemocy- anin from Carcinus aestuarii contains three major and two minor structural sub- units. Here, we reveal the primary structure of the γ-type 75 kDa subunit of Carcinus aestuarii hemocyanin, CaeSS2, and combine structure-based sequence alignments, tryptophan fluorescence, and glycosylation analyses to provide insights into the structural and functional organisation of CaeSS2. We identify three functional domains and three conserved histidine residues that most likely participate in the formation of the copper active site in domain 2. Oxygen-binding ability of Carcinus aestuarii Hc and its structural subunit 2 was studied using CD and fluorescence spec- troscopy. Removing the copper dioxygen system from the active site led to a decrease of the melting temperature, which can be explained by a stabilizing effect of the bind- ing metal ion. To study the quenching effect of the active site copper ions in hemocy- anins, the copper complex Cu II (PuPhPy) 2+ was used, which appears as a very strong quencher of the tryptophan emission. Furthermore, the structural localization was clarified and found to explain the observed fluorescence behavior of the protein. Sugar analysis reveals that CaeSS2 is glycosylated, and oligosaccharide chains con- nected to three O-glycosylated and one N-glycosylated sites were found. |
| Databáze: | OpenAIRE |
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