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Substrate inhibition in bioreactors occurs when the concentration of substrate (such as glucose, salts, or phenols [1]) exceeds the optimal parameters and reduces the growth rate of the cells within the bioreactor. This is often confused with substrate limitation, which describes environments in which cell growth is limited due to of low substrate.
NADP-malic enzyme is one of three decarboxylation enzymes used in the inorganic carbon concentrating mechanisms of C4 and CAM plants. The others are NAD-malic enzyme and PEP carboxykinase . [ 2 ] [ 3 ] Although often one of the three photosynthetic decarboxylases predominate, the simultaneous operation of all three is also shown to exist.
in which e is the concentration of free enzyme (not the total concentration) and x is the concentration of enzyme-substrate complex EA. Conservation of enzyme requires that [28] = where is now the total enzyme concentration. After combining the two expressions some straightforward algebra leads to the following expression for the concentration ...
In plants, both enzymes can catalyze the oxidation of ortho-diphenols substrates into their corresponding ortho-quinones. The key difference between the two related enzymes is that tyrosinase can catalyze the hydroxylation of monophenols to diphenols (monophenolase activity) as well as the oxidation of the o-diphenol to the o-quinone ...
Many enzymes, especially those involved in catabolic pathways, are subject to this repressive regulation. A powerful method of overcoming the catabolite repression in the enzyme biosynthesis is a fed-batch culture in which glucose concentration in the culture liquid is kept low, where growth is restricted, and the enzyme biosynthesis is ...
The amount of substrate needed to achieve a given rate of reaction is also important. This is given by the Michaelis–Menten constant (K m), which is the substrate concentration required for an enzyme to reach one-half its maximum reaction rate; generally, each enzyme has a characteristic K M for a given substrate.
They are classified according to the effect of the inhibitor on the V max (maximum reaction rate catalysed by the enzyme) and K m (the concentration of substrate resulting in half maximal enzyme activity) as the concentration of the enzyme's substrate is varied. [15] [16]
Enzymes catalyze chemical reactions involving the substrate(s). In the case of a single substrate, the substrate bonds with the enzyme active site, and an enzyme-substrate complex is formed. The substrate is transformed into one or more products, which are then released from the active site. The active site is then free to accept another ...