In vitro stabilization of acv synthetase activity fromStreptomyces clavuligerus
ACV synthetase (ACVS) fromStreptomyces clavuligerus is very labile. The study and in vitro application of this important enzyme for cephamycin biosynthesis requires a relatively stable preparation. The stability of the crude enzyme was substantially increased by dithio-threitol and the cofactor, magnesium (Mg2+). The purified enzyme was also unstable and especially sensitive to moderate to high temperature. Addition of the substrate L-valine (L-val) along with the cofactors (ATP and MG2+) raised the thermal inactivation temperature, and increased the stability of the enzyme at low temperature. Amino acids capable of replacing L-val as ACVS substrate generally stabilized the enzyme. The ACVS level remained high during fermentation in a complex medium containing high concentrations of amino acids, in contrast to the situation in chemically-defined medium.
Index EntriesStreptomyces clavuligerus cephamycin ACV synthetase stability stabilization L-valine fermentation
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