title: Kinetic analysis of the lactate-dehydrogenase-coupled reaction process and measurement of alanine transaminase by an integration strategy.
abstract: Kinetic analyses of lactate-dehydrogenase (LD)-coupled alanine transaminase (ALT) reaction processes were investigated for measuring ALT by an integration strategy. For measuring ALT by a kinetic analysis of an LD-coupled ALT reaction curve, candidate reaction curves were calculated via iterative numerical integration of the differential velocity equations to execute a weighted nonlinear-least-square-fitting. To realize the integration strategy, the conventional initial-velocity method was used if the ALT activities were below 25 U/L; otherwise, kinetic analyses of the reaction curves were employed. Of the reaction curves recorded at 10-s intervals, kinetic analyses gave ALT activities resistant to deviations in the LD kinetic parameters. The integration strategy yielded a higher value of the lower limit, but an upper limit of over 100 U/L by simulations and over 75 U/L with purified ALT. Also, its intra-run relative standard deviations were below 9% for 0.50 U/L ALT and below 5% for final 1 to 65 U/L ALT. The integration strategy gave consistent ALT activities in clinical sera. Hence, this new approach for kinetic analyses of ALT reaction processes and the integration strategy were effective to measure ALT.
authors.affiliation: Unit for Biotransfromation and Protein Biotechnology, Chongqing Medical University, Chongqing 400016, PR China.
authors.forename: Xiaolan
authors.initials: X
authors.lastname: Yang
authors.forename: Beizhong
authors.initials: B
authors.lastname: Liu
authors.forename: Yu
authors.initials: Y
authors.lastname: Sang
authors.forename: Yonghua
authors.initials: Y
authors.lastname: Yuan
authors.forename: Jun
authors.initials: J
authors.lastname: Pu
authors.forename: Yin
authors.initials: Y
authors.lastname: Liu
authors.forename: Zhirong
authors.initials: Z
authors.lastname: Li
authors.forename: Juan
authors.initials: J
authors.lastname: Feng
authors.forename: Yanling
authors.initials: Y
authors.lastname: Xie
authors.forename: Renkuan
authors.initials: R
authors.lastname: Tang
authors.forename: Huidong
authors.initials: H
authors.lastname: Yuan
authors.forename: Fei
authors.initials: F
authors.lastname: Liao
mesh_terms: D000410:Alanine Transaminase / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D007770:L-Lactate Dehydrogenase / Q000737:chemistry / Q000378:metabolism*
chemical_list: D007770:L-Lactate Dehydrogenase; D000410:Alanine Transaminase