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Logistic Enzyme Kinetics
Published in Mihai V. Putz, New Frontiers in Nanochemistry, 2020
Mihai V. Putz, Ana-Maria Putz, Corina Duda-Seiman, Daniel Duda-Seiman
In the case of metabolic proteins, enzymes, it has been shown that their activities may be influenced and regulated by other molecules than substrates, of small shape, identified as activators or inhibitors (Cantor and Schimmel, 1980; Copeland, 2000). In the theory of allosteric regulation, it is established that the binding of a substrate (ligand) at a specific site is influenced by the binding of another different ligand identified as an inhibitor at a different or allosteric site on the protein/enzyme. This principle is applicable at the cellular level resulting in cellular regulation where organism needs are translated into metabolic processes via different protein/enzymatic pathways. Protein synthesis determined by gene expression is only a part of this process of RNA transcription which has to provide a perfect balance in the genome maintenance by repeated signalization started by other cells or bio-inspired nano-implants (Curran et al., 2005). The complex substrate-enzyme plays the role of molecular messengers.
Cell Physiology
Published in Wei-Shou Hu, Cell Culture Bioprocess Engineering, 2020
An enzyme may also be subject to allosteric regulation, meaning that its activity is modulated by the binding of an effector molecule to the enzyme. For example, the binding of the product of the reaction can decrease the enzyme activity (i.e., feedback inhibition). In many biosynthetic pathways in microbial systems, the first enzyme in the pathway is feedback inhibited by the product of the pathway. Upon the accumulation of the product, its activity is decreased to reduce the flux through the pathway and to prevent wasteful accumulation of the product. Different isozymes may be subject to different allosteric regulations. Isoforms may also respond differently to hormonal or signaling stimuli.
Enzyme Kinetics and Drugs as Enzyme Inhibitors
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2019
Allosteric regulation (or control) means the influence of an effector molecule on an enzyme and plays a role in cell signaling (long-range allosteric effects); it binds at a site other than the enzyme’s active site, the allosteric site. This is often accompanied by conformational changes involving protein dynamics. Effector molecules either cause positive allosteric modulation (allosteric activation) or negative allosteric modulation (allosteric inhibition) and are in a broader sense of importance for conformational perturbations on cellular functions and disease states; in other words the allosteric change in one protein may affect the behavior of other proteins downstream. Non-competitive inhibition always means allosteric inhibition but not all allosteric inhibitors act non-competitive. For models explaining the allosteric effect see Monod et al. (1965; concerted model) and Koshland et al. (1966, sequential model).
Subsets of adjacent nodes (SOAN): a fast method for computing suboptimal paths in protein dynamic networks
Published in Molecular Physics, 2021
Thomas Dodd, Xin-Qiu Yao, Donald Hamelberg, Ivaylo Ivanov
Allosteric regulation is a key functional feature of many proteins and protein complexes, involving communication between distal protein regions. The process is initiated by ligand binding or some other structural or dynamic perturbation, which occurs at one site and is subsequently propagated through the protein to influence the activities at a distal site. Knowledge of allosteric communication mechanisms has an impact on the fields of rational drug discovery [1] and protein design [2]. While classical models of allosteric regulation have suggested that a binding event induces substantial conformational changes in the distal site [3,4], other studies have observed allostery in the absence of large-scale conformational change [5,6]. This suggests that subtle differences in dynamics can alter the population distribution of the conformational ensemble without drastically altering the average conformation of the biomolecule.
Exploration of ligand-induced protein conformational alteration, aggregate formation, and its inhibition: A biophysical insight
Published in Preparative Biochemistry and Biotechnology, 2018
Saima Nusrat, Rizwan Hasan Khan
Binding of ligands induces conformational changes in the protein, like loop or domain rearrangements. But, in maximum circumstances, variation in the structure of protein backbone is minor.[50] Some ligands are agonists that stimulate the receptor to initiate ligand binding process,[51] while some ligands are antagonists that block the receptor and act as a competitive inhibitor for such activated ligands, so deactivate the protein. The induction of conformational changes upon ligand binding stimulates the binding affinity of the adjacent molecules interacting with the same receptor and this is called as allosteric regulation.[52,53] In general, the ligand binding is categorized into four groups: