Pakistan Journal of Biological Sciences1028-88801812-5735Asian Network for Scientific Information10.3923/pjbs.2006.409.417QuadanFarouk AlAltrabshehBilal 3200693Computer simulation of single substrate single product reversible enzyme reactions directions using LabVIEW graphical programming software is described. The program determines and displays reactions direction, calculates concentrations of reactant and product as they occur and allows graphical, digital and spread sheet outputs; Red blood cells Triose Phosphate Isomerase (TPI) reaction direction proceeds initially in the forward direction (G3P to DHAP) for 46 reaction cycles; then, reaction direction oscillates. During oscillation, the rate of forward reaction (G3P to DHAP) is slower than the backward reaction rate (DHAP to G3P). It takes 16 reaction cycles in forward direction to match 3 reaction cycles in the reverse direction (16F/3R). the direction oscillation pattern of TPI is ((5F/1R)2 (6F/1R)1)n, that is a twice repeat of 5 consecutive forwards followed by 1 backward direction, followed by a single repeat of 6 consecutive forwards and one backward directions and is repeated continuously. Direction oscillation pattern for TPI is km dependent and it is more sensitive to forward km (for G3P) value. Computer simulation of reversible reactions is a new research tool that provides information not possible by the traditional means of enzyme activity measurements.]]>Ainscow, E.K. and M.D. Brand,1999266737749Betz, A. and B. Chance,1964109586586Bali, M. and S.R. Thomas,2001324185199Cornish-Bowden, A. and J.H. Hofmeyer,199178993Chance, B. and K. Wassermann,19864529042957Cornish-Bowden, A. and M.L. Cardenas,200126866166624Dano, S., P.G. Sorensen and F. Hynne,1999402320322Ehlde, M. and G. Zacchi,199511201207Elia, M.,199554213232Hess, B. and A. Boiteux,197140237258Jackson, R.C.,199385539545Kalkman, C.J.,1995115158Melendez-Hevia, E., F. Mateo and N.V. Torres,199211519Mendes, P.,199322361363McDonald, I.A. and J. Webber,199554267274Mulquiney, P.J. and P.W. Kuchel,1999342581596Novoselov, K.P., D.B. Shirabaikin, S.Y. Umanskii, A.S. Vladimirov, A.K.H. Minushev and A.A. Korkin,20022313753189Periappuram, C.L. Steinhauer, D.L. Barton, D.C. Taylor, B. Chatsonand and J. Zou,200012211931199Richter, P.H. and J. Ross,1981211715716Regan, L. and M. Gregory,199542151161Shulman, R.G.,1988in vivo.]]>133739Sugden, M.C., M.J. Holness and T.N. Palmer,1989263313323Tomita, M., K. Hashimoto, K. Takahashi, T.S. Shimiza and Y. Matsozaki et al.,1999157284Weber, J., F. Hoffmann and U. Rinas,2002Escherichia coli during temperature-induced recombinant protein production: 2. Redirection of metabolic fluxes.]]>80320330