1. The effects of acclimatization temperature on the catalytic properties of acetylcholinesterase from rainbow-trout brain were examined. 2. Trout brain acetylcholinesterase occurs in two distinct forms. A single ‘warm’ variant of the enzyme is present after acclimatization to 17°C; a single ‘cold’ variant appears after acclimatization to 2°C. Both forms are present in fish after acclimatization to an intermediate temperature. 3. The Km values of the enzyme variants for acetylcholine are temperature-dependent, the lowest values coinciding with the acclimatization temperature at which each enzyme was induced. 4. It is concluded that the Km–temperature relationship is adaptive, and that the critical process during thermal acclimatization, in cases where enzymes show sharp changes in Km with temperature, is the synthesis of a new enzyme variant that is better suited for catalysis and control of catalysis under the conditions of the acclimatized state.
Research Article| March 01 1970
Functional significance of isoenzymes in thermal acclimatization. Acetylcholinesterase from trout brain
Biochem J (1970) 116 (5): 883–887.
- Views Icon Views
- Share Icon Share
- Cite Icon Cite
John Baldwin, P. W. Hochachka; Functional significance of isoenzymes in thermal acclimatization. Acetylcholinesterase from trout brain. Biochem J 1 March 1970; 116 (5): 883–887. doi: https://doi.org/10.1042/bj1160883
Download citation file: