“…Valine is likely catabolized to methylmalonate semialdehyde via an incomplete cycle of β‐ox (Bachhawat et al ., 1957; Robinson and Coon, 1957) and then converted to propionyl‐CoA and CO 2 (Sokatch et al ., 1968). A. nidulans lacks methylmalonyl‐CoA mutase, an enzyme of the mammalian valine catabolism pathway, as assessed biochemically (Ledley et al ., 1991) and by BLAST analysis, but contains a homologue of the bacterial propionyl‐CoA‐yielding methylmalonate semialdehyde dehydrogenase, locus AN3591.2. Despite the similarities in the β‐ox steps, the only common enzyme between the isoleucine, valine, and strain‐chain fatty acid pathways in mammals is the enoyl‐CoA hydratase (Robinson et al ., 1956; Bachhawat et al ., 1957; Ikeda et al ., 1983; Luo et al ., 1995).…”