Fructose-1,6-bisphosphatase in mantle of the sea mussel Mytilus galloprovincialis Lmk.—III. Seasonal variation of enzymatic activity

Abstract

1. 1. Fructose-1,6-bisphosphatase (FBPase-1) from the mantle and the posterior adductor muscle (PAM) of Mytilus galloprovincialis Lmk. was investigated over almost 2 years for changes in specific activity and the apparent Michaelis constant ( K m) for Fru-1,6-P 2 (purified enzyme preparations). 2. 2. The specific activity of the mantle changed, peaking in a period between August and November. 3. 3. The K m values for the substrate changed seasonally being low during the first part of the year (January–May) and high in the period between October and November. 4. 4. The changes in mantle FBPase-1 activity were discussed in relation to the effect of modulators and the possible seasonally covalent modification of the enzyme. 5. 5. No statistical changes were detected in posterior adductor muscle FBPase-1, which is in keeping with the glycolytic role suggested for the tissue.