K. Jernejc et M. Legisa, PURIFICATION AND PROPERTIES OF CARNITINE ACETYLTRANSFERASE FROM CITRIC-ACID PRODUCING ASPERGILLUS-NIGER, Applied biochemistry and biotechnology, 60(2), 1996, pp. 151-158
Carnitine acetyltransferase was purified from the citric acid producin
g A. niger mycelium with a protein band showing a relative molecular w
eight of 77,000 and a pH optimum of 7.3. The Km values for the purifie
d enzyme for acetyl-CoA and for carnitine were 0.1 mM and 1 mM, respec
tively. Carnitine acetyltransferase was located both in the mitochondr
ia and in the cytosol. Both mitochondrial and cytosolic enzyme were pu
rified using ammonium sulfate precipitation, Mono Q and Superose 12 se
paration. Regarding the localization, except for maximum velocity, the
re were no differences observed in substrate specificity and inhibitio
n. Inhibition of the enzyme with micromolar concentrations of Cu2+ cou
ld contribute to a greater citric acid biosynthesis. Carnitine acetylt
ransferase can be considered as an enzyme necessary for the transport
of acetyl groups through mitochondrial membrane in both directions.