Displays acyl-CoA thioesterase activity with short chain aliphatic acyl-CoA thioesters, such as propionyl-CoA and butyryl-CoA. Enzyme activity is relatively low, suggesting that the acyl-CoA thioesters used in the assays are not the physiological substrates. Has no detectable activity with 4-hydroxybenzoyl-CoA, lauroyl-CoA (C12:0), arachidoyl-CoA (C20:0) and arachidonoyl-CoA (C20:4). kcat is 0.44 sec(-1) with propionyl-CoA, 0.54 sec(-1) with iso-butyryl-CoA and 0.17 sec(-1) with n-butyryl-CoA. Belongs to the 4-hydroxybenzoyl-CoA thioesterase family.