A study of the distribution of acyl-CoA hydrolases and acyl-L-carnitine hydrolases in guinea-pig small intestine.

1. Acyl-CoA hydrolase activities, using palmitoyl-CoA and decanoyl-CoA as substrates, were highest in the proximal part and lowest in the distal part of the guinea-pig small intestine. Butyryl-CoA hydrolase activity was not found in any of the homogenates. 2. The acyl-CoA hydrolases showed a complex subcellular distribution when compared to classical marker enzymes. The specific activity of the hydrolase was highest in the microsomal fraction, and lowest in the soluble fraction when palmitoyl-CoA was used as substrate. When decanoyl-CoA was used as substrate, highest activity was found in the mitochondrial/lysosomal fraction and lowest in the microsomal fraction. 3. Gel filtration on an ultrogel AcA-44 column separated the palmitoyl-CoA hydrolase of the cytosol fraction into three or four fractions. 4. Palmitoyl-carnitine hydrolase was present in the microsomal and the nuclei fractions. The distribution was mostly similar to the alkaline phosphatase suggesting a brush border localization.