Rate saturation definition

The turnover number of an enzyme is defined as the maximum number of moles of substrate reacted per mole of enzyme (or molecules per molecule) per minute under optimum conditions (i.e., saturating substrate concentration, optimum pH, etc). If 2 mg/cm3 of a pure enzyme (50,000 molecular weight, Michaelis constant Km = 0.03 mole/m3) catalyzes a reaction at a rate of 2.5 jumoles/nUksec when the substrate concentration is 5 x 10 3 moles/m3, determine the turnover number corresponding to this definition and the actual number of moles of substrate reacting per minute per mole of enzyme. 

The interpretation of the elements of the matrix 0 is slightly more subtle, as they represent the derivatives of unknown functions fi(x) with respect to the variables x at the point x° = 1. Nevertheless, an interpretation of these parameters is possible and does not rely on the explicit knowledge of the detailed functional form of the rate equations. Note that the definition corresponds to the scaled elasticity coefficients of Metabolic Control Analysis, and the interpretation is reminiscent to the interpretation of the power-law coefficients of Section VII.C Each element 6% of the matrix measures the normalized degree of saturation, or likewise, the effective kinetic order, of a reaction v, with respect to a substrate Si at the metabolic state S°. Importantly, the interpretation of the elements of does again not hinge upon any specific mathematical representation of specific... 

The crystal surface may be regarded as covered with a layer of saturated solution of a definite thickness through which the products have to diffuse. If the actual solvation of the solid proceeds rapidly in comparison to the process of diffusion the rate of solution wfil he essentially that of diffusion, and can accordingly be expressed by the Fick diffusion equation, the rate of solution per unit area of interface being given by... 

By the above definition, b is positive for crystal dissolution, and negative for crystal growth. During convective crystal dissolution, the dissolution rate u is directly proportional to b. During diffusive crystal dissolution, the dissolution rate is proportional to parameter a, which is positively related to b. Hence, for the dissolution of a given mineral in a melt, the size of parameter b is important. The numerator of b is proportional to the degree of undersaturation. If the initial melt is saturated, b = 0 and there is no crystal dissolution or growth. The denominator characterizes the concentration difference between the crystal and the saturated... 

The hydrate formed by photolysis of this substance is one of the few such products (the others are uracil hydrate, 5-fluorouracil hydrate, and uridine hydrate) that have actually been isolated and compared with authentic material of known structure.7 It is nearly the only product formed in the photolysis, is definitely stable at room temperature and neutral pH, and the thermal reversal to dimethyluracil is nearly quantitative. These properties, as Moore observed, make the reaction ideal for mechanistic investigation. Burr and Park have investigated the reaction mechanism by measuring the photolysis rate of dimethyluracil in mixtures of water with several nonaqueous, nonreactive solvents as a function of water concentration.64 The photolysis rate for 10" iM DMU was found to be the same in water-saturated cyclohexane (about 5 x 10-3M in water) as in dry cyclohexane. The photolysis rate in dry, highly purified dioxane was quite insensitive to water, and it was observed that hydrate formation (measured by thin-layer chromatography and by thermal absorbance reversal) became appreciable only at water concentrations above 40%. 

The activation parameters reported for the exchange process in 19 and 20 are definitively lower than the expected values for saturated systems (Table 2, compare to Me2Zn exchange barriers shown in Section II.C.l). Values in Table 2 are referred to the experimental rate of exchange kexp at the given concentration, i.e. which is neither concentration nor statistically corrected according to the molecularity of the reaction. The actual rate... 

The second process of water vapor removal down the channel can be described by the convective flux, Q(pw,Sat PvMet)KRTA), representing the maximum amount of water vapor removed with the purge gas when the exit purge gas is fully saturated with vapor. In the above definition Q is the purge gas volumetric flow rate and A the active area of the fuel cell. Both parameters defined above have the unit of mol/s per unit of the fuel cell active area. It follows that... 

It should be kept in mind that, in spite of these major variations in the CO2-carbonic acid system, virtually all surface seawater is supersaturated with respect to calcite and aragonite. However, variations in the composition of surface waters can have a major influence on the depth at which deep seawater becomes undersaturated with respect to these minerals. The CO2 content of the water is the primary factor controlling its initial saturation state. The productivity and temperature of surface seawater also play major roles, in determining the types and amounts of biogenic carbonates that are produced. Later it will be shown that there is a definite relation between the saturation state of deep seawater, the rain rate of biogenic material and the accumulation of calcium carbonate in deep sea sediments. 

D Choice A is a restatement of Le Chatelier s Principle. B is a definition of equilibrium. A constant humidity (Choice C) occurs if the rate of vaporization and condensation are equal, indicating equilibrium. No solid is present in an unsaturated solution. If solid is added, all of it dissolves indicating a lack of equilibrium. D would be true for a saturated soution. 

The reactions of OH, like those of H, involve mainly addition to unsaturated sites and abstraction from saturated compounds. Oxidation or reduction by OH or H, respectively, involving charge transfer has not been definitely established with any organic compound. While the relative reactivities of H and OH follow similar patterns, the absolute rate of reaction with OH is generally higher than that with H. 

---