Marine Biotechnology

, Volume 10, Issue 1, pp 31–38

Carbonic Anhydrase in Calcified Endoskeleton: Novel Activity in Biocalcification in Alcyonarian

  • M. Azizur Rahman
  • Tamotsu Oomori
  • Tsuyoshi Uehara
Original Article

DOI: 10.1007/s10126-007-9030-4

Cite this article as:
Rahman, M.A., Oomori, T. & Uehara, T. Mar Biotechnol (2008) 10: 31. doi:10.1007/s10126-007-9030-4

Abstract

Carbonic anhydrase (CA) is a key enzyme in the chemical reaction of living organisms and has been found to be associated with calcification in a number of invertebrates including calcareous sponges, but until now no direct evidence has been advanced to show CA activity in alcyonarian corals. However, it is essential to understand the role of CA in the process of biocalcification in alcyonarian. Here we describe the novel activity of CA and its relationship to the formation of calcified hard tissues in alcyonarian coral, Lobophytum crassum. We find that two CA proteins, which were partially purified by electro-elution treatment, can control the morphology of CaCO3 crystals and one of them is potentially involved in the process of biocalcification. Previously, we isolated CA from the total extract of alcyonarian, and further, we report here a single protein, which has both calcium-binding and CA activities and is responsible for CaCO3 nucleation and crystal growth. This matrix protein inhibited the precipitation of CaCO3 from a saturated solution containing CaCl2 and NaHCO3, indicating that it can act as a negative regulator for calcification in the sclerites of alcyonarians. The effect of an inhibitor on the enzyme activity was also examined. These findings strongly support the idea that carbonic anhydrase domain in alcyonarian is involved in the calcification process. Our observations strongly suggest that the matrix protein in alcyonarian coral is not only a structural protein but also a catalyst.

Keywords

alcyonarian coralbiomineralizationcalcificationcalcitecalcium carbonatecarbonic anhydraseorganic matrixproteinsclerites

Copyright information

© Springer Science+Business Media, LLC 2007

Authors and Affiliations

  • M. Azizur Rahman
    • 1
  • Tamotsu Oomori
    • 2
  • Tsuyoshi Uehara
    • 1
  1. 1.Department of Marine and Environmental SciencesUniversity of the RyukyusOkinawaJapan
  2. 2.Department of Chemistry Faculty of ScienceUniversity of the RyukyusOkinawaJapan