Journals / Turkish Journal of Zoology / 2008 / Cilt: 32 - Sayı: 3
Characterization of Branchial Na,K-ATPase from Three Freshwater Fish Species (Oreochromis niloticus, Cyprinus carpio, and Oncorhynchus mykiss)
- Journal
- Turkish Journal of Zoology
- Pages
- 299–304
- DOI
- —
Abstract
Branchial Na,K-ATPase activity was characterized in 3 freshwater fish species (Oncorhynchus mykiss, Oreochromis niloticus, and Cyprinus carpio) with different ecological needs. Na+, K+, and Cl- concentrations in the gills were also measured. The maximal Na,K-ATPase activity was observed at 100 mM Na+, 20-40 mM K+, 3-4 mM Mg2+, and 1 mM ouabain. The maximal velocity (Vmax) of Na,K-ATPase isolated from O. mykiss (1.07 µmol Pi/mg prot/h) was lower than that isolated from O. niloticus (7.25 µmol Pi/mg prot/h) and C. carpio (7.44 µmol Pi/mg prot/h). Nevertheless, Na+, K+, and Cl- levels in O. mykiss were higher than the others. The lowest Vmax value can be attributed to the highest ion concentrations in the gills of O. mykiss. However, substrate concentrations, which give half of Vmax (Km) of Na,K-ATPase in the gills of O. niloticus and C. carpio, were different although they exhibited similar Vmax values. The low Km value in the gills of O. niloticus compared to C. carpio may be related to high resistance to changing environmental factors.
Özet
Bu çal›flmada farkl› ekolojik gereksinimleri olan üç farkl› tatl› su bal›¤›nda (O. niloticus, C. carpio, O. mykiss) solungaç Na,KATPaz enzimlerinin karakterizasyonu yap›lm›flt›r. Ayn› zamanda solungaçlarda Na+, K+ ve Cl- düzeyleri de belirlenmifltir. En yüksek Na,K-ATPaz aktivitesi 100 mM Na+, 20 mM K+, 3-4 mM Mg+2, 1 mM Ouabain deriflimlerinde gözlenmifltir. O. mykiss’da (1,07 µmol Pi/mg prot/h), O. niloticus (7,25 µmol Pi/mg prot/h) ve C. carpio (7,44 µmol Pi/mg prot/h) ile karfl›laflt›r›ld›¤›nda gözlenen en düflük maximal h›z (Vmax) de¤eri, solungaçlardaki yüksek iyon düzeyleri ile iliflkilendirilebilir. Buna karfl›l›k, O. niloticus ve C. carpio’da yar› Vmax de¤erine sahip substrat deriflimleri (Km) ise, benzer Vmax de¤erlerine karfl›l›k farkl›l›k göstermektedir. O. niloticus’da C. carpio’ya oranla gözlenen düflük Km de¤erinin, de¤iflen ortam koflullar›nda O. niloticus’un daha dirençli olmas›ndan kaynaklanabilece¤i bildirilmifltir.