Temperature and enzyme activity in poikilotherms. Isocitrate dehydrogenases in rainbow-trout liver

Abstract

1. The kinetics of the thermally induced enzyme variants of the supernatant NADP-isocitrate dehydrogenase from rainbow-trout liver are investigated. 2. Fish acclimatized to 2 degrees C (cold-adapted enzyme) and 17 degrees C (warm-adapted enzyme) show different relative distributions of the three NADP-isocitrate dehydrogenase isoenzymes; this has been demonstrated with electrophoresis and electrofocusing techniques. 3. Plots of K(m) versus temperature for the cold-adapted and warm-adapted enzyme variants are complex in nature with apparent maximal enzyme-substrate affinity corresponding to the temperature at which the trout is acclimatized. Both substrates, dl-isocitrate and NADP(+), give similar curves although the magnitude of the K(m) change with temperature is much decreased in the case of NADP(+). 4. E(a) values of approx. 18kcal/mol were determined for both the cold-adapted and warm-adapted enzyme variants. 5. In an attempt to determine how velocities can be increased at low temperatures, cation, pH requirements, metabolite and enzyme concentrations were examined. 6. NAD-isocitrate dehydrogenase could not be detected in trout tissues.

The effects of temperature and pH on the apparent Michaelis constant of glutathione reductase from maize (Zea mays L.)

“…It is not unusual for apparent Km values for the different substrates of a single enzyme to show different temperature responses in vitro. This has been demonstrated for enzymes of both animal (Moon & Hochachka, 1971) and plant origin (Badger & Collatz 1977;Simon & Vairinhos 1991).…”

Evidence for an in vivo conformational change in ribulose bisphosphate carboxylase–oxygenase from Puma rye during cold adaptation

“…The formation of isozymes of differing primary structure is promoted or repressed by low temperature (5, 6,7). Except for an ABBREVIATIONS: DTNB, 5,5'-dithiobis(2-nitrobenaoic acid): RUBP, ribulose-l,5-bisphosphate; RUBPCase, ribulose-1,5-bisphosphate carboxylase-oxygenase (EC 4.1.1.39); RH, cold-hardened rye; RNH, won-cold-hardened rye; SDS, sodium dodecyl sulfate; DTT, dithiothreitol; BEAE, diethylaminoethyl : MW, molecular weight.…”

Effects of temperature and feeding frequency on ingestion and growth for rare minnow

“…Water temperature and feeding frequency are two important components affecting growth, which have been studied in several fish species such as Channel catfish [38], European seabass [39], rainbow trout [40,41], Tiger Puffer [42], tilapia [24], pikeperch [43], and Asian seabass [44]. Temperature affects food consumption, digestion rate, and growth rate through variations in metabolism [15,45], use of nutrients and energy [18,46], and digestive enzyme activities [17,[47][48][49]. Although optimal temperature and feeding frequency differ in various species, most fish have their specific peaks of maximum food consumption, optimum growth, and preferred range of temperature [50].…”