Two forms of Serratia marcescens acetolactate synthase (designated ALS I and ALS II) have been separated by utilizing DEAE-Sephacel column chromatography with the combination of stepwise and a linear gradient elution of increasing ionic strength. The ...
Two forms of Serratia marcescens acetolactate synthase (designated ALS I and ALS II) have been separated by utilizing DEAE-Sephacel column chromatography with the combination of stepwise and a linear gradient elution of increasing ionic strength. The native molecular weights of the two forms of ALS as determined by Sephacryl S-400 gel filtration method appears to be 572,000 and 531,400 for ALS I and ALS II, respectively. Feedback inhibition studies indicate that ALS I is far more sensitive to inhibition by valine, leucine and isoleucine than ALS II. On the other hand, ALS II is far more sensitive to α-ketobutyrate inhibition than ALS I. The two forms of ALS also have differences in sensitivity against two different classes of herbicides, sulfonylurea and imidazolinone. These data suggest that the two forms of ALS are physically and functionally distinct.