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Nitrate binding to limulus polyphemus subunit type II hemocyanin and its functional implications

Publication ,  Journal Article
Hazes, B; Magnus, KA; Kalk, KH; Bonaventura, C; Hol, WGJ
Published in: Journal of Molecular Biology
1996

The horseshoe crab, Limulus polyphemus, employs hemocyanin as an oxygen carrier in its hemolymph. This hemocyanin displays cooperative oxygen binding and heterotropic allosteric regulation by protons, chloride ions and divalent cations. Here, we report the crystal structure of Limulus polyphemus subunit type II hemocyanin with a nitrate ion bound in the interface of its first and second domains. Interestingly, the nitrate-binding site coincides with the binding site for the allosteric effector chloride. Oxygen-binding data indeed indicate that nitrate, like chloride, reduces the oxygen affinity of this hemocyanin. The observed binding of two distinct anions to a single site suggests that several other anions may also bind at this site. This opens the intriguing possibility that bicarbonate, which is structurally similar to nitrate and closely linked to respiration, can act as an allosteric effector that lowers the oxygen affinity. Such an effect could be another factor in the repertoire of allosteric regulators of this hemocyanin; however, the physiological implications will be a challenge to decipher, since there exists a complex interplay of effects between bicarbonate, chloride, pH and divalent cations.

Duke Scholars

Published In

Journal of Molecular Biology

DOI

ISSN

0022-2836

Publication Date

1996

Volume

262

Issue

4

Start / End Page

532 / 542

Related Subject Headings

  • Biochemistry & Molecular Biology
  • 0605 Microbiology
  • 0601 Biochemistry and Cell Biology
  • 0304 Medicinal and Biomolecular Chemistry
 

Citation

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Hazes, B., Magnus, K. A., Kalk, K. H., Bonaventura, C., & Hol, W. G. J. (1996). Nitrate binding to limulus polyphemus subunit type II hemocyanin and its functional implications. Journal of Molecular Biology, 262(4), 532–542. https://doi.org/10.1006/jmbi.1996.0533
Hazes, B., K. A. Magnus, K. H. Kalk, C. Bonaventura, and W. G. J. Hol. “Nitrate binding to limulus polyphemus subunit type II hemocyanin and its functional implications.” Journal of Molecular Biology 262, no. 4 (1996): 532–42. https://doi.org/10.1006/jmbi.1996.0533.
Hazes B, Magnus KA, Kalk KH, Bonaventura C, Hol WGJ. Nitrate binding to limulus polyphemus subunit type II hemocyanin and its functional implications. Journal of Molecular Biology. 1996;262(4):532–42.
Hazes, B., et al. “Nitrate binding to limulus polyphemus subunit type II hemocyanin and its functional implications.” Journal of Molecular Biology, vol. 262, no. 4, 1996, pp. 532–42. Scival, doi:10.1006/jmbi.1996.0533.
Hazes B, Magnus KA, Kalk KH, Bonaventura C, Hol WGJ. Nitrate binding to limulus polyphemus subunit type II hemocyanin and its functional implications. Journal of Molecular Biology. 1996;262(4):532–542.
Journal cover image

Published In

Journal of Molecular Biology

DOI

ISSN

0022-2836

Publication Date

1996

Volume

262

Issue

4

Start / End Page

532 / 542

Related Subject Headings

  • Biochemistry & Molecular Biology
  • 0605 Microbiology
  • 0601 Biochemistry and Cell Biology
  • 0304 Medicinal and Biomolecular Chemistry