Tissues biochemical systems

M2. Mapson, L. W., Enzyme systems associated with the oxidation and reduction of glutathione in plant tissues. Biochem. Soc. Symposia (Cambridge, Engl.) 17, 28-42 (1959). 

Part II of this book represents the bulk of the material on the analysis and modeling of biochemical systems. Concepts covered include biochemical reaction kinetics and kinetics of enzyme-mediated reactions simulation and analysis of biochemical systems including non-equilibrium open systems, metabolic networks, and phosphorylation cascades transport processes including membrane transport and electrophysiological systems. Part III covers the specialized topics of spatially distributed transport modeling and blood-tissue solute exchange, constraint-based analysis of large-scale biochemical networks, protein-protein interactions, and stochastic systems. 

Here we focus on the issue of how to build computational models of biochemical reaction systems. The two foci of the chapter are on modeling chemical kinetics in well mixed systems using ordinary differential equations and on introducing the basic mathematics of the processes that transport material into and out of (and within) cells and tissues. The tools of chemical kinetics and mass transport are essential components in the toolbox for simulation and analysis of living biochemical systems. 

One-dimensional advection will be used in Chapter 8 as a component in models of cellular biochemical systems that are coupled to blood-tissue solute exchange. 

The ultimate example studied in this chapter is the mitochondrial respiratory system and oxidative ATP synthesis. This system, in which biochemical network function is tightly coupled with membrane transport, is essential to the function of nearly all eukaryotic cell types. As an example of a critically important system and an analysis that makes use of a wide range of concepts from electrophysiology to detailed network thermodynamics, this model represents a milestone in our study of living biochemical systems. To continue to build our ability to realistically simulate living systems, the following chapter covers the treatment of spatially distributed systems, such as advective transport of substances in the microcirculation and exchange of substances between the blood and tissue. 

EDTA ° In this drug preparation, calcium is bound as complex and can be displaced from the ions of heavy metals. These metals are bound loosely in the biochemical systems of the tissues and are liberated easily from them. 

Thyroxine is one of the few hormones for which unequivocal effects on isolated biochemical systems can be observed in particular, it has been shown that thyroxine at high concentrations has a direct effect on mitochondrial oxidation. Tissues from animals which have been injected with thyroid extracts or purified thyroxine show a raised oxygen consumption, particularly in liver and muscle. Similarly the addition of thyroxine to tissue slices of the same organs results in increased oxidation. Thyroxine seems to be especially trapped by the mitochondria, where it stimulates the... 

Injury, by physical or chemical agents, is a threat to homeostasis. It will produce a temporary upset in the otherwise well-controlled functioning of many major physiological and biochemical systems, and unless adequate regeneration of the damaged tissue is effected, may result in... 

In some biochemical systems the limiting mass transfer step shifts from a gas-liquid or solid-liquid interface (as discussed earlier) to the interior of solid particles. The most important cases are solid substrates and cell aggregates (such as microbial floes, cellular tissues, etc.) and immobilized enzymes (gel-entrapped or supported in solid matrices). In the former, diffusion of oxygen (or other nutrients) through the particle limits metabolic rates, while in the latter, substrate reactant or product diffusion into or out of the enzyme carrier often limits the overall global bioreaction rates. 

In order to develop a valid concept on the active site of Insulin and thereby construct a synthetic model it would be helpful to have the many known chemical modifications evaluated in those biochemical systems known to be affected by Insulin. Furthermore these modified insulins should be evaluated in test systems now utilized for defining the tissue receptor site. Finally, by comparing this data with circular dlchrolsm, sedimentation data, and in certain selected cases, electron density data, it should be possible to analyze the significance of insulin s three-dimensional configuration for the significant amino acids relative to the disulfide bridges O. 

Since then the investigations of microbial systems were continued and extended to the electrochemical and electronic behavior of plant and mammalian tissues. Therefore, now one can say that we are really in the midst of it all. Undoubtedly life might sometimes appear simpler if research activities were restricted to isolated biochemical systems incorporated into artificial membranes. Unfortunately it is almost impossible to extrapolate these findings... 

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