Modelling And Analysis Of Expression And Regulation Of Trp And Lac Operons

trp and lac operons were usedsas the research object in this paper and two extended mathematical models were proposed on the basis of previous works. The parameters of the model were determined and the results were analyzed. A steady-state optimization model of tryptophan biosynthesis was established based on indirect optimization method (IOM). The network analysis was used to lac operon system.The first part of this paper is to set up a novel mathematical model describing expression and regulation of trp operon, in which not only the effects of repression and attenuation on transcription are taken into consideration, but the interaction between repression gene and structural gene as well as the transportation of tryptophan across cell membrane are also considered. An expended mathematical model is established to describe the trp operon on the level of transcription, translation, and enzyme catalysis by taking the integrated effects of repression, feedback, inhibition, attenuation, interaction between genes and excretion of product into consideration. The robustness of this model is discussed by using the S-system model. And the influences of cell growth rate on the biosynthesis of tryptophan, stability and dynamic behavior of the trp operon are investigated. A steady-state optimization model is established. It maximizes the accumulative term accounting for both consumption and secretion. The nonlinear optimization problem is approximately transformed to a linear optimization problem.The second part in this paper, an integrated model includes catabolite repression, inducer exclusion, lactose hydrolysis to glucose and galactose, and synthesis and degradation of allolactose. The genes, mRNA and enzymes which mainly influence the system were investigated via the analysis of S-system model and network of lac operon. The glucose effect was studied based on the level of bionetwork.