Proceedings of the Indian Academy of Sciences - Chemical Sciences

, Volume 93, Issue 8, pp 1289-1304

First online:

Chemical probes into the active centre of a heme thiolate monoxygenase

  • P K BhattacharyyaAffiliated withDepartment of Biochemistry, University of IllinoisDepartment of Organic Chemistry, Indian Institute of Science
  • , T B SamantaAffiliated withDepartment of Biochemistry, University of Illinois
  • , A H J UllahAffiliated withDepartment of Biochemistry, University of Illinois
  • , I C GunsalusAffiliated withDepartment of Biochemistry, University of Illinois

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Linalool-8-monoxygenase, a typical bacterial P-450 heme thiolase, shows a high degree of substrate specificity towards linalool. The active site of the pure enzyme has been probed with a large number of substrate analogues with systematic alterations or conformational variations in the linalool molecule. The comparison of three parameters, the mo→mos conversion of the enzyme as a result of substrate binding monitored at 392 nm, theK D of the analogues giving information about energies of association and the relative turnover as substrate have given information about the space-filling characteristics of the substrates in the enzyme cleft, the number of contacts the molecules make with the respective domains of the enzyme and the distance of the site undergoing hydroxylation from the oxygen site, respectively. The data permit the conclusion that linalool makes contact with the enzyme by hydrogen bonding with the hydroxyl group as well through hydrophobic association with all the eight carbons carrying hydrogen in the molecules.


Enzymes oxygenases P-450 hydroxylases structure of monooxygenase substrate analogues enzyme kinetics intermolecular associations