Anewthermokineticreducedextentmethodforstudyingofthereversiblecompetitiveinhibitionofsinglesubstrateenzyme-catalyzedreactionswasproposedinthispaper.Thereactionthatarginase-catalyzedhydrolysisofL-argininetoL-ornithineandureaandtheinhibitionofthisreactionbytheproduct,L-ornithine,andexogenousL-lysinewerestudiedat37℃in40mmol·L^-1sodiumbarbiturate-HC1buffersolution(pH=9.4).MichealisconstantKmforarginineandmaximumvelocityVmofthereactionweredeterminedtobe5.14mmol·L^-1and1.13×10^-2mmol·L^+1·s^-1,respectively.TheproductinhibitionconstantKpandinhibitoryconstantK1ofL-lysineweredeterminedtobe1.18and5.6mmol.L-l,respectively.Alltheresultshavebetterrepeatabilityandself-consistencyandareinagreementwithliteraturevalues.Thisnewmethodusingmoredirectthermalinformationfromtheprocesswouldgivemorereliablekineticinformationthanthetraditionalinitialratemethod.
