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Allosteric regulation of an enzyme. In the fields of biochemistry and pharmacology an allosteric regulator (or allosteric modulator) is a substance that binds to a site on an enzyme or receptor distinct from the active site, resulting in a conformational change that alters the protein's activity, either enhancing or inhibiting its function.
Allosteric enzymes need not be oligomers as previously thought, [1] and in fact many systems have demonstrated allostery within single enzymes. [2] In biochemistry , allosteric regulation (or allosteric control ) is the regulation of a protein by binding an effector molecule at a site other than the enzyme's active site .
A simplified reaction mechanism for N-acetylglutamate synthase (NAGS). Two mechanisms for N-acetyltransferase function have been proposed: a two-step, ping-pong mechanism involving transfer of the relevant acetyl group to an activated cysteine residue [10] and a one-step mechanism through direct attack of the amino nitrogen on the carbonyl group. [11]
The particular arrangement of catalytic and regulatory subunits in this enzyme affords the complex with strongly allosteric behaviour with respect to its substrates. [3] The enzyme is an archetypal example of allosteric modulation of fine control of metabolic enzyme reactions. ATCase does not follow Michaelis–Menten kinetics.
PFK1 is an allosteric enzyme and has a structure similar to that of hemoglobin in so far as it is a dimer of a dimer. [5] One half of each dimer contains the ATP binding site whereas the other half the substrate (fructose-6-phosphate or (F6P)) binding site as well as a separate allosteric binding site. [6]
In molecular biology and genetics, transcriptional regulation is the means by which a cell regulates the conversion of DNA to RNA (transcription), thereby orchestrating gene activity. A single gene can be regulated in a range of ways, from altering the number of copies of RNA that are transcribed, to the temporal control of when the gene is ...
This is a diagram of allosteric regulation of an enzyme. When inhibitor binds to the allosteric site the shape of active site is altered, so substrate cannot fit into it. An allosteric site is a site on an enzyme, unrelated to its active site, which can bind an effector molecule. This interaction is another mechanism of enzyme regulation.
Double-stranded DNA phage lysins tend to lie within the 25 to 40 kDa range in terms of size. A notable exception is the streptococcal PlyC endolysin, which is 114 kDa. PlyC is not only the biggest and most potent lysin, but also structurally unique since it is composed of two different gene products, PlyCA and PlyCB, with a ratio of eight PlyCB subunits for each PlyCA in its active conformation.