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The net effect is an extracellular concentration of sodium ions which is 5 times the intracellular concentration, and an intracellular concentration of potassium ions which is 30 times the extracellular concentration. [1] The sodium–potassium pump was discovered in 1957 by the Danish scientist Jens Christian Skou, who was awarded a Nobel ...
The sodium–potassium pump, a critical enzyme for regulating sodium and potassium levels in cells. Sodium ions (Na +) are necessary in small amounts for some types of plants, [1] but sodium as a nutrient is more generally needed in larger amounts [1] by animals, due to their use of it for generation of nerve impulses and for maintenance of electrolyte balance and fluid balance.
Enzymes can be classified by two main criteria: either amino acid sequence similarity (and thus evolutionary relationship) or enzymatic activity. Enzyme activity. An enzyme's name is often derived from its substrate or the chemical reaction it catalyzes, with the word ending in -ase.
For a given enzyme concentration and for relatively low substrate concentrations, the reaction rate increases linearly with substrate concentration; the enzyme molecules are largely free to catalyse the reaction, and increasing substrate concentration means an increasing rate at which the enzyme and substrate molecules encounter one another.
, which is often written as , [5] represents the limiting rate approached by the system at saturating substrate concentration for a given enzyme concentration. The Michaelis constant K m {\displaystyle K_{\mathrm {m} }} has units of concentration, and for a given reaction is equal to the concentration of substrate at which the reaction rate is ...
An elevation of the reaction temperature from 37 °C to 50–60 °C may increase the activity several times, like the addition of 0.5–1% sodium dodecyl sulfate (SDS) or Guanidinium chloride (3 M), Guanidinium thiocyanate (1 M) and urea (4 M) [disputed (for: no source cited for temperature) – discuss]. The above-mentioned conditions enhance ...
Increasing the substrate concentration increases the rate of reaction (enzyme activity). However, enzyme saturation limits reaction rates. An enzyme is saturated when the active sites of all the molecules are occupied most of the time. At the saturation point, the reaction will not speed up, no matter how much additional substrate is added.
The relative activity of a species i, denoted a i, is defined [4] [5] as: = where μ i is the (molar) chemical potential of the species i under the conditions of interest, μ o i is the (molar) chemical potential of that species under some defined set of standard conditions, R is the gas constant, T is the thermodynamic temperature and e is the exponential constant.