TY - JOUR
T1 - Self-association and oxygen-binding characteristics of the isolated subunits of Limulus polyphemus hemocyanin
AU - Brenowitz, Michael
AU - Bonaventura, Celia
AU - Bonaventura, Joseph
N1 - Funding Information:
Portions of this work are taken from the Ph.D. thesis of MB. presented to Duke University in the spring of 1982. This work was supported by Grant PCM 7946462 from the National Science Foundation.
PY - 1984/4
Y1 - 1984/4
N2 - The hemocyanin of the horseshoe crab Limulus polyphemus is characteristic of arthropod hemocyanins in that it is a high-molecular-weight oligomer composed of functionally and structurally distinct subunits. The protein forms a 48-subunit complex, the largest form of arthropod hemocyanin, whose oxygen-binding characteristics are modulated by subunit interaction within the oligomer. It has previously been shown that a number of electrophoretic isozymes, which are identical immunochemically, are present in dissociated Limulus hemocyanin. In this study it is demonstrated that the electrophoretic differences in the antigenically identical subunits are not reflected in their oxygen-binding and self-assembly properties or in the roles they play in reassembly and function of the 48-subunit native molecule. The chloride-dependent modulation of the oxygen-binding properties of those Limulus subunits which do not self-assemble, as documented here, illustrates that this allosteric effect may be operable at the tertiary level. For each of the purified subunits the effects of pH and calcium ions on oxygen-binding characteristics and self-assembly reactions are reported, and the roles of specific subunits in reassembly of distinct aggregation states are further documented.
AB - The hemocyanin of the horseshoe crab Limulus polyphemus is characteristic of arthropod hemocyanins in that it is a high-molecular-weight oligomer composed of functionally and structurally distinct subunits. The protein forms a 48-subunit complex, the largest form of arthropod hemocyanin, whose oxygen-binding characteristics are modulated by subunit interaction within the oligomer. It has previously been shown that a number of electrophoretic isozymes, which are identical immunochemically, are present in dissociated Limulus hemocyanin. In this study it is demonstrated that the electrophoretic differences in the antigenically identical subunits are not reflected in their oxygen-binding and self-assembly properties or in the roles they play in reassembly and function of the 48-subunit native molecule. The chloride-dependent modulation of the oxygen-binding properties of those Limulus subunits which do not self-assemble, as documented here, illustrates that this allosteric effect may be operable at the tertiary level. For each of the purified subunits the effects of pH and calcium ions on oxygen-binding characteristics and self-assembly reactions are reported, and the roles of specific subunits in reassembly of distinct aggregation states are further documented.
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U2 - 10.1016/0003-9861(84)90105-X
DO - 10.1016/0003-9861(84)90105-X
M3 - Article
C2 - 6712235
AN - SCOPUS:0021414376
SN - 0003-9861
VL - 230
SP - 238
EP - 249
JO - Archives of Biochemistry and Biophysics
JF - Archives of Biochemistry and Biophysics
IS - 1
ER -