Carbonic anhydrase is essential for the cellular transportation of hydrogen and bicarbonate ions and plays a key role in a wide variety of physiological processes. Rainbow trout, Oncorhynchus mykiss is an important freshwater fish in aquaculture industry and is known to be one of the most susceptible species to environmental contamination. In this study, carbonic anhydrase was detected in the kidney and intestine of rainbow trout. Carbonic anhydrase was isolated from cytosolic proteins and identified by using SDS-PAGE, isoelectric focusing, and immunohistochemical methods. A specific protein band with molecular weight of 30 kDa and pI of 7.0 was detected by Western blotting. The immunohistochemical results showed that carbonic anhydrase was located at various cells in the kidney and intestine of rainbow trout.

Carbonic anhydrases catalyze the hydration of carbon dioxide and are essential for regulation of cellular pH and carbon dioxide transport. CA is the zinc metalloenzyme that catalyses the reversible reactions of CO2 with water. To date, 16 isozymes belonging to the α-CA gene family. A carbonic anhydrase isozyme is present in shaggy sea raven, Hemitripterus villosus. Carbonic anhydrase isozyme protein isolated from several tissues showed specific protein band with molecular weight of 30 kDa. The isolated protein band was identified as a carbonic anhydrase isozyme.

본 연구는 농어, Lateolabrax japonicus에서 Carbonic anhydrase Ⅲ (CA Ⅲ)의 발현 양상을 관찰하고자 농어의 각 조직에서 Bradford 방법을 이용하여 가용성 단백질의 함량을 조사하였고, SDS-PAGE와 western blot analysis로 CA Ⅲ의 분자량을 조사하였으며 IEF와 western blot analysis로 CA Ⅲ의 등전점을 관찰하였다. 또한, 비교 분석을 위하여 동일한 방법으로 무지개송어, Oncorhynchus mykiss의 각 조직에서도 CA Ⅲ의 분자량과 등전점을 확인하였고 두 어류의 가용성 단백질을 ELISA법을 이용하여 CA Ⅲ의 상대농도를 비교 분석하였다. Bradford 분석에서 가용성 단백질의 함량은 상대적으로 무지개송어가 높게 나타났으며 ELISA분석에서도 CA Ⅲ의 상대농도가 무지개송어에서 높게 관찰되었다. SDS-PAGE와 western blot analysis 분석 결과 두 어류의 조직에서 분자량 30,000 (Da)의 band가 확인되었으며 IEF와 western blot analysis 분석 결과 등전점 (pI) 7.0에서 band가 확인되었다.