Biochemical studies on the activity of delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine synthetase from Streptomyces clavuligerus.
The enzyme activity of purified delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine (ACV) synthetase from Streptomyces clavuligerus was studied biochemically. The dependence of ACV synthetase activity on reaction parameters, including substrates, cofactors, temperature and pH, were determined, resulting in a substantially increased enzyme activity. The activity is very labile to high temperature and is also unstable at acidic pH. The enzyme specificity is strict towards L-alpha-aminoadipate, but rather loose with respect to L-valine; certain modifications of L-cysteine can also be tolerated. Some unnatural tripeptides synthesized by ACV synthetase can be converted into bioactive compounds by isopenicillin N synthase. The only nutrient found to negatively affect ACV synthetase activity is phosphate, but various compounds such as thiol-blocking reagents and ATP-utilization products (AMP and pyrophosphate) are inhibitory to the enzyme.
Zhang
J
J
Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.
Wolfe
S
S
Demain
A L
AL
D015074:2-Aminoadipic Acid / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000494:pharmacology; D002021:Buffers; D002384:Catalysis; D003545:Cysteine / Q000378:metabolism; D004795:Enzyme Stability; D005978:Glutathione / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D009994:Osmolar Concentration; D010453:Peptide Synthases / Q000378:metabolism*; D013302:Streptomyces / Q000201:enzymology*; D013379:Substrate Specificity; D013696:Temperature; D014633:Valine / Q000378:metabolism
D002021:Buffers; D015074:2-Aminoadipic Acid; D000255:Adenosine Triphosphate; D010453:Peptide Synthases; C095368:alpha-aminoadipyl-cysteinyl-valine synthetase; D005978:Glutathione; D014633:Valine; D008274:Magnesium; D003545:Cysteine