ニジマス肝臓のβ-ガラクトシダーゼに関する研究-III

異なる組成の飼料を与えた当才魚の酵素活性とアイソザイムパターン

抄録

The activities of β-galactosidase and lactase, and the pattern of β-galactosidase isozymes were investigated to see the effect of dietary lactose and starch on the enzyme of the rainbow trout.
The lactase activity of the fish tissue was increased by the high carbohydrate feeds, especially by the high lactose feed which was reported to cause the elevation of the lactase activity in the calf intestine²⁾. On the other hand, the β-galactosidase activity in the liver and kidney was rather decreased by the high carbohydrate feeds, although the β-galactosidase of E. coli was known to be induced by lactose in the medium³⁾.
These results may be a possible evidence for the concept that the animal β-galactosidase (o-NPGa-ase) is not identical with lactase^4-8).
Three isozymes of -galactosidase (I, III, and IV) were isolated by a Sephadex G-200 column from all tissues of the rainbow trout yearling, but the isozyme II being found in the 2-year fish¹⁾ was not detected. The pattern of the isozyme seemed to be tissue specific, and not influenced by the dietary composition. The molecular weights of the isozymes were the multiples of 57, 000: ×6 (I), ×3 (II), ×2 (III), and ×1 (IV).
The lactase activity was not recovered from a Sephadex G-200 column.