Concentrations of Leucine Aminonaphthylamidase (LAN) and Soluble Protein in Tissues of Rainbow Trout, Salmo gairdneri

Abstract

The levels of soluble protein (Biuret-reactive) and levels of leucine aminonaphthylamidase (LAN, 3.4.1.1) were determined quantitatively in extracts of 10 organs from rainbow trout (Salmo gairdneri). Soluble protein had a very discrete distribution and averaged 5.2 times more concentrated in liver than in blood plasma (3.5 g/100 mL). LAN was present in the extract of every tissue except saline-washed brain. LAN activity was highest in hindgut, 36 more times more concentrated than in the plasma of healthy fish. Wasting disorders such as caused by stress, would likely increase the level of necrosis which in turn would increase the amount of LAN in plasma. I propose that a "tissue equivalent" unit of LAN to provide a means of relating increased LAN in plasma to an amount of liver destruction in vitro that would render a similar amount of LAN.Key words: plasma enzymes, stress, plasma protein, rainbow trout, leucine aminonaphthylamidase, fish physiology