COLD-ACCLIMATION INCREASES FATTY-ACID-BINDING PROTEIN-CONCENTRATION IN AEROBIC MUSCLE OF STRIPED BASS, MORONE-SAXATILIS

Fatty acid-binding protein was isolated from aerobic skeletal muscle o f the striped bass Mel-one saxatilis. FABP from striped bass (MS-FABP) has a molecular mass of 14,800 Da (as estimated by SDS-PAGE) and bind s long-chain fatty acids with I:1 molar stoichiometry and with micromo lar affinity Binding dissociation constants, as estimated by liposome assay, were 0.63 +/- 0.44, 0.82 +/- 0.12, and 1.60 +/- 0.44 mu M for p almitic (16:0), oleic (18:1), and palmitoleic (16:1) acids, respective ly. No significant difference was detected in MS-FABP's binding affini ty among these fatty acids or those estimated by competitive displacem ent assay (22:6, 20:5, and 18:0). Acclimation of striped bass from 25 degrees C to 5 degrees C caused an increase in FABP concentration in a erobic skeletal muscle (5 degrees C = 1.4 +/- 0.12 mg/g wet weight; wa rm = 1.04 +/- 0.11 mg/g wet weight). The magnitude of this increase ma tches the predicted decrease in diffusion coefficient of FABP at 5 deg rees C. Previous studies, however, report that fatty acid oxidation is not only maintained but increased in cold-acclimated fish. We specula te that FPBP may increase flux of fatty acids through beta-oxidation ( in cold-acclimated fish) by an increase in the percent of FABP molecul es carrying fatty acid. (C) 1996 Wiley-Liss, Inc.