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Updated: Aug 13, 2026

Isolation and Chemical Characterization of Lipid A from Gram-negative Bacteria
Published on: September 16, 2013
[Isolation, purification and properties of acetolactate synthase from cultured Lactococcus lactis]
Iu S Kisrieva1, V M Serebrennikov, E V Eneĭskaia
1Bach Institute of Biochemistry, Russian Academy of Sciences, Leninskii pr. 33, Moscow, 117071 Russia.
Abstract:
Acetolactate synthase catalyzing the synthesis of alpha-acetolactate was isolated from lactic acid bacteria Lactococcus lactis subsp. lactis biovar. diacetylactis 4 and purified. Acetolactate synthase was shown to be an allosteric enzyme with low affinity for the substrate: the Km for pyruvate was 70 mM. The curve relating the dependence of enzyme activity on pyruvate concentration had a sigmoid shape. The enzyme activity persisted for 24 h in the presence of stabilizers, pyruvate, and thiamine pyrophosphate. Acetolactate synthase had the pH optimums of 5.8 and 6.5-7.0 in acetate and phosphate buffers, respectively. The temperature optimum for this enzyme was 38-40 degrees C at pH 6.5. The molecular weight of acetolactate synthase was 150 kDa. In Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate showed that the enzyme consisted of three identical subunits with a molecular weight of 55 kDa.
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