Molecular Structure of the Arthropod Hemocyanins

The molecular heterogeneity of hemocyanin: Structural and functional properties of the 4×6-meric protein of Upogebia pusilla (Crustacea)

“…More hexamers may eventually be combined into 2 × 6, 4 × 6, 6 × 6 or 8 × 6 oligohexamers. The particular aggregation form, in which the oxygen carrier is found, is highly species dependent, and more than one form may coexist in the same species (Markl and Decker, 1992). Significant differences in primary structures exist within the different subunits building the heterohexamers found in one species as well as within the Hcs subunits of different species.…”

The molecular heterogeneity of hemocyanin: Its role in the adaptive plasticity of Crustacea

“…The subunit-subunit interactions that stabilize the monomers in the hexameric oligomers have been described with high precision in the case of the hexameric Hc of Panulirus interruptus that has been crystallized (Linzen et al, 1985;Volbeda and Hol, 1989;Markl and Decker, 1992). Furthermore sequence comparisons have demonstrated that the residues involved in such intra-hexameric contact areas are strongly conserved in evolution (Linzen et al, 1985).…”

“…Detailed analyses of structural heterogeneity have led to the recognition of distinct subunit types which differ in immunogenicity and in their specific roles in complex oligomerization (Markl et al, 1979a(Markl et al, ,b, 1986Markl, 1986;Markl and Decker, 1992). Hcs sequencing has provided a clear identification of distinct subunits in several species allowing for a precise definition of subunit families and of their phylogenetic relationships (Burmester, 2001).…”

“…Numerous studies have investigated the origin and the architecture of the three protein domains that represent the characteristic fold of the subunits (Linzen et al, 1985;Salvato and Beltramini, 1990;van Holde et al, 2001;Decker and Terwilliger, 2000). The Gene 398 (2007) 192 -201 www.elsevier.com/locate/gene quaternary arrangement and the different oligomeric assemblages have been reviewed to delineate reliable models for the different Hc structures (Markl and Decker, 1992;Magnus et al, 1994). Other authors have reviewed the functional properties of Hcs with particular consideration of the narrow links between physiological plasticity and environmental selection (Truchot, 1992;Terwilliger, 1998).…”

Allosteric Models for Multimeric Proteins: Oxygen-Linked Effector Binding in Hemocyanin

“…Furthermore, binding of both purines was measured under hypoxic conditions using isothermal titration calorimetry (ITC) 1 and compared to the results obtained previously for H. Vulgaris under normoxic conditions (31). The experiments were performed at different pH values to address the allosteric coupling between protons and the two purines in hemocyanin of H. Vulgaris.…”