# Purification, Characterization, cDNA Cloning, and Bioinformatic Analysis of Zinc-Binding Protein from Magallana hongkongensis

## TL;DR

Researchers discovered a new zinc-binding protein in Hong Kong oysters, which is similar to carbonic anhydrase found in other oyster species.

## Contribution

A novel zinc-binding protein was purified and characterized from Magallana hongkongensis, with its full-length cDNA cloned and sequenced.

## Key findings

- The purified protein has a molecular weight of approximately 36 kDa.
- MhCA shares 89.74% homology with carbonic anhydrase from Crassostrea gigas.
- Molecular docking shows zinc ions coordinate with histidine residues in MhCA.

## Abstract

Oysters contain significant amounts of the zinc element, which may also be found in their proteins. In this study, a novel zinc-binding protein was purified from the mantle of the oyster Magallana hongkongensis using two kinds of gel filtration chromatograms. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) showed that its molecular weight was approximately 36 kDa. The protein identified by the Q-Exactive mass spectrometer shared the highest sequence identity with carbonic anhydrase derived from Crassostrea gigas concerning amino acid sequence similarity. Based on homologous cloning and RACE PCR, the full-length cDNA of carbonic anhydrase from Magallana hongkongensis (designated as MhCA) was cloned and sequenced. The cDNA of MhCA encodes a 315-amino-acid protein with 89.74% homology to carbonic anhydrase derived from Crassostrea gigas. Molecular docking revealed that the two zinc ions primarily form coordination bonds with histidine residues in the MhCA protein. These results strongly suggest that MhCA is a novel zinc-binding protein in Magallana hongkongensis.