title: An enzyme-centric approach for modelling non-linear biological complexity.
abstract: BACKGROUND
  The current challenge of Systems Biology is to integrate high throughput data sets for simulating the complexity of biological networks, exploit the evolution of nature-designed networks that maintain the robustness of a biological system, and thereby generate novel, experimentally testable hypotheses. In order to simulate non-linear biological complexities, we have previously developed an Enzyme-Centric mechanistic modeling approach and validated it using metabolic network in E. coli. The idea is to use prior knowledge of catalytic and regulatory mechanisms of each enzyme within the metabolic network to build a dynamic model for investigating the network level regulation and thus understand the nature design principle behind the network.
  
  
  RESULTS
  In this paper, we further demonstrate the application of complex enzyme catalytic and regulatory modules to simulate nonlinear network regulatory patterns vs. simple linear conversion model. We learned and validated that it is essential to incorporate prior knowledge from the literature to simulate non-linear biological complexities. The network expandability is demonstrated and validated with the complex amino acid biosynthetic network with multi-regulations. Also, we demonstrated the compatibility of mechanistic models within close species. Furthermore, the eukaryotic protein factory model for insuring steady mRNA production is simulated and the coupling of RNA transcription and splicing is validated by both mathematical simulation and experimental analysis.
  
  
  CONCLUSIONS
  We demonstrated the importance of modeling complex enzyme catalytic and regulatory mechanisms to further understand nonlinear network regulatory patterns. The simulations presented in this paper reveal how a living system maintains homeostasis and its robustness to continue functioning while facing environmental stresses or genetic mutations.
authors.affiliation: Harold C, Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA. chinrang.yang@utsouthwestern.edu
authors.forename: Chin-Rang
authors.initials: CR
authors.lastname: Yang
mesh_terms: D000596:Amino Acids / Q000096:biosynthesis; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D004798:Enzymes / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D006706:Homeostasis; D016014:Linear Models; D053858:Metabolic Networks and Pathways; D008954:Models, Biological; D009154:Mutation; D010600:Pharmacology; D012326:RNA Splicing; D012475:Salmonella / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D012680:Sensitivity and Specificity; D014158:Transcription, Genetic
chemical_list: D000596:Amino Acids; D004798:Enzymes; D012321:DNA-Directed RNA Polymerases