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Specific Enzyme Activity
Enzyme assays are laboratory methods for measuring enzymatic activity. They are vital for the study of enzyme kinetics and enzyme inhibition. Enzyme units The quantity or concentration of an enzyme can be expressed in molar amounts, as with any other chemical, or in terms of activity in enzyme units. Enzyme activity Enzyme activity is a measure of the quantity of active enzyme present and is thus dependent on various physical conditions, ''which should be specified''. It is calculated using the following formula: :\mathrm=\mathrm_\text=\mathrm\times\mathrm where :\mathrm = Enzyme activity :\mathrm_\text = Moles of substrate converted per unit time :\mathrm = Rate of the reaction :\mathrm = Reaction volume The SI unit is the katal, 1 katal = 1 mol s−1 (mole per second), but this is an excessively large unit. A more practical and commonly used value is enzyme unit (U) = 1 μmol min−1 (micromole per minute). 1 U corresponds to 16.67 nanokatals. Enzyme activity as giv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stopped Flow
Stopped-flow is one of a number of methods of studying the kinetics of reactions in solution. It is ideal for studying chemical reactions with a typical dead time on the order of 1 millisecond. In the simplest form of the technique, the solutions of two reactants are rapidly mixed by being forced through a mixing chamber, on emerging from which the mixed fluid passes through an optical observation cell. At some point in time, the flow is suddenly stopped, and the reaction is monitored using a suitable spectroscopic probe, such as absorbance, Fluorescence spectroscopy, fluorescence or Fluorescence anisotropy, fluorescence polarization. The change in spectroscopic signal as a function of time is recorded, and the rate constants that define the reaction kinetics can then be obtained by fitting the data using a suitable model. Stopped-flow as an experimental technique was introduced by Britton Chance and extended by Quentin Gibson. Other techniques, such as the Temperature jump, temper ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
