. Biophysics: concepts and mechanisms. Biophysics. ON CHEMICAL REACTION RATES; ENZYMES 195 Since the specific rates are all different, the steady-state concentrations are different; but if the process is in the steady-state condition, the concentra- tions are constant. If the back reactions proceed at a measurable rate, the situation is more complicated, but the principles are the same. When you hear the word "equilibrium" used, then think: Which is meant, true equilibrium or steady-state? In the latter case, continuous processing occurs; in the former no net reaction occurs. Figure
. Biophysics: concepts and mechanisms. Biophysics. ON CHEMICAL REACTION RATES; ENZYMES 195 Since the specific rates are all different, the steady-state concentrations are different; but if the process is in the steady-state condition, the concentra- tions are constant. If the back reactions proceed at a measurable rate, the situation is more complicated, but the principles are the same. When you hear the word "equilibrium" used, then think: Which is meant, true equilibrium or steady-state? In the latter case, continuous processing occurs; in the former no net reaction occurs. Figure 8-1 illustrates this difference. source (lake) tumbling stream. Equilibrium Steady State Figure 8-1. Equilibrium and Steady State. ON CHEMICAL REACTION RATES; ENZYMES Concentration and Temperature The law of mass action has already been outlined under the discussion of the approach of a system toward true equilibrium. The rate is always pro- portional to some power of the concentration of reactants, and this index is called the "order" of a reaction. There are really two orders obtainable from experiments, one with respect to time, and the other with respect to concentration. These will have the same value if the reaction is a simple one in which the slowest step is the first step, the one which involves reactant concentrations explicitly. If some other step than the primary one is rate-determining, or if products interfere with or inhibit the reaction, the power, a, of the concentration, [A], which describes best the over-all rate may be different from that which describes the initial rate. Complicated cases are not considered here. Some of the simpler cases are collected in Table 8-1, which shows the rate equation and the expression and dimensions of the proportionality constant, k, called the specific rate con- stant, when a = 0, 1/2, 1, and 2. In Table 8-2 are collected values of the specific rate constant for some first and second-order Please note th
Size: 1470px × 1699px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollectionbiodiversi, booksubjectbiophysics
