α-methylacetoacetyl

α-meth·yl·ac·e·to·ac·e·tyl (meth″əl-ə-se″to-asґə-tēl″) the acyl radical of α-methylacetoacetic acid; the thioester formed with coenzyme A, α-methylacetoacetyl CoA, is an intermediate in the catabolism of isoleucine.