Activates endogenous long-chain fatty acids (LCFA) by esterification of the fatty acids into metabolically active CoA-thioesters for subsequent degradation or incorporation into phospholipids (PubMed:8206942). Acts preferentially on C16 and C18 fatty acids with a cis-double bond at C-9-C-10 (PubMed:8206942). a long-chain fatty acid + ATP + CoA = a long-chain fatty acyl-CoA + AMP + diphosphate (9Z)-octadecenoate + ATP + CoA = (9Z)-octadecenoyl-CoA + AMP + diphosphate ATP + CoA + hexadecanoate = AMP + diphosphate + hexadecanoyl-CoA (9Z)-hexadecenoate + ATP + CoA = (9Z)-hexadecenoyl-CoA + AMP + diphosphate (9Z)-tetradecenoate + ATP + CoA = (9Z)-tetradecenoyl-CoA + AMP + diphosphate (9Z,12Z)-octadecadienoate + ATP + CoA = (9Z,12Z)-octadecadienoyl-CoA + AMP + diphosphate Optimum pH is 7.7. Optimum temperature is 25 degrees Celsius. Interacts with FRK1. The FACS motif is required for catalytic activity and substrate specificity. Present with 6440 molecules/cell in log phase SD medium. Belongs to the ATP-dependent AMP-binding enzyme family.