Non-competitive inhibition

Summary

Non-competitive inhibition is a type of enzyme inhibition where the inhibitor reduces the activity of the enzyme and binds equally well to the enzyme whether or not it has already bound the substrate. This is unlike competitive inhibition, where binding affinity for the substrate in the enzyme is decreased in the presence of an inhibitor. The inhibitor may bind to the enzyme whether or not the substrate has already been bound, but if it has a higher affinity for binding the enzyme in one state or the other, it is called a mixed inhibitor. History During his years working as a physician Michaelis and a friend (Peter Rona) built a compact lab, in the hospital, and over the course of five years – Michaelis successfully became published over 100 times. During his research in the hospital, he was the first to view the different types of inhibition; specifically using fructose and glucose as inhibitors of maltase activity. Maltase breaks maltose into two units

Official source

https://en.wikipedia.org/wiki/Non-competitive_inhibition

About this result

This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.

Related publications (16)

Related publications

Related people

Related units

Related concepts (8)

Related concepts

Related courses (10)

Related courses

Related lectures (29)

Related lectures

The role of TIF1 gamma during adult murine hematopoiesis

Konstantin Shakhbazov

Transforming Growth Factor beta (TGFβ) signaling plays an important role in a variety of cellular processes during embryonic development, adult tissue homeostasis and cancer. TGFβI ligand is a potent inhibitor of early hematopoietic progenitor [1] cells in vitro, however the exact role and mechanisms of this pathway during adult hematopoietic homeostasis remains poorly understood. The Transcriptional Intermediary Factor 1 gamma (Tif1γ) gene encodes a recently uncovered nuclear protein in the TGFβ transduction pathway. Tif1γ is defective in the zebrafish moonshine mutant, which exhibits primitive and definitive hematopoiesis defects [2]. In addition, Tif1γ has been shown to influence differentiation of human erythroid cells in vitro [3]. Recent work in our laboratory has provided genetic evidence that Tif1γ is required for the generation and survival of hematopoietic stem/progenitor cells during murine development (C.Adolphe, K.Shakhbazov et al., manuscript under submission). Given that Tif1γ function is required for embryonic development and null mutants are embryonic lethal [4] (R.Losson unpublished data), we took advantage of a conditional Tif1γ flox allele (R.Losson unpublished data) and combined it with the inducible MxCre line [5] to generate mice in which Tif1γ function can be specifically ablated during adult hematopoiesis. MxCre:Tif1γKO/flox mutants exhibit a decrease in erythroblasts and dramatic increase in granulocytes within the bone marrow. This phenotype is attributable to a massive increase in granulocyte-monocyte progenitors (GMPs) at the expense of common myeloid progenitors (CMPs) and megakaryocyte- erythrocyte progenitors (MEPs), which are severely decreased in Tif1γ mutant bone marrow. In addition, pre-B cells were dramatically decreased in numbers, attributable to an increase in cell death, indicating a pro-survival role for Tif1γ in B lymphocytes. In addition, we performed deletion of Tif1γ in non-competitive and competitive bone marrow transplantation settings, which indicated that only the CMP/MEP phenotype is a non-cell autonomous effect. Two distinct models have been reported suggesting how Tif1γ functions within the TGFβ pathway: one indicating that Tif1γ binds and acts through Smad2/3 and the other that Tif1γ functions as a Smad4 mono-ubiquitin ligase [3, 6, 7]. To genetically address this apparent discrepancy, we generated double Tif1γ/Smad4 hematopoietic specific mutant mice, whose phenotype was surprisingly similar to that observed in Tif1γ single mutants. These data suggest that Tif1γ function is independent of Smad4 in hematopoietic cells. To address the mechanism by which Tif1γ functions, we performed microarray profiling of normal and mutant progenitors, which revealed prostaglandin D2 synthase as a hub gene linking Tif1γ and TGFβ signaling. Finally, we were able to mimic the hematopoietic-Tif1γ null phenotype by providing 16,16-dimethyl prostaglandin D2 to wild-type hematopoietic cells in vitro. In summary, our data provide genetic evidence for a key role of Tif1γ during early myeloid development as well as pre-B cell survival. In addition, we have identified that the majority of Tif1γ function is Smad4 independent. Finally, we identified a novel link between Tif1γ function and prostaglandin metabolism/signaling as a likely mechanism by which Tif1γ regulates hematopoiesis.

EPFL2009

Conduramine F-1 epoxides: synthesis and their glycosidase inhibitory activities

Sylvain Favre, Pierre Vogel

Starting from (+/-)-7-oxanorbornenone ((+/-)-14), (+/-)-(1RS, 2RS, 3SR, 6SR)-6-azidocyclohex-4-en-1,2,3-triol ((+/-)-24) and (+/-)- 1RS, 2RS, 3SR, 6RS)-6-azidocyclohex-4-en-1,2,3-triol ((+/-)-26) were obtained. Epoxidation of the latter cyclohexene derivative gave two epoxides (+/-)-30 and (+/-)-31 that were converted into (+/-)-conduramine F-1 epoxides (+/-)-10 and (epoxides (+/-)-30 and (+/-)-31 that were converted into (+/-)-conduramine F-1 epoxides (+/-)-10 and (+/-)-11 and N-substituted derivatives (+/-)-12 and (+/-)-13. Compound (+/-)-(1RS, 2SR, 3RS, 4SR, 5RS, 6SR)-5-({[4-(trifluoromethyl) phenyl] methyl} amino)-7-oxabicyclo[4.1.0]heptane-2,3,4- triol ((+/-)-12c) is a good, non-competitive inhibitor of beta-xylosidase from Aspergillus niger (K-i=2.2 mu M), and (+/-)( 1RS, 2RS, 3SR, 4RS, 5SR, 6SR)-5-{[(biphenyl-4-yl) methyl] amino}-7-oxabicyclo[4.1.0] heptane-2,3,4-triol ((+/-)-13d) is a good inhibitor of alpha-glucosidase from brewer's yeast (Ki 2.8 mu M, non-competitive). (c) 2007 Elsevier Ltd. All rights reserved.

2007

The 5-hydroxytryptamine 3 receptor (5-HT3R) is a member of the pentameric ligand-gated ion channel (pLGIC) family, that plays an important role in fast signal transduction and cell-cell communication in synapses: They convert a chemical signal from a neurotransmitter into the electrical signal that represents the action potential. Activation of 5-HT3R with serotonin triggers a range of molecular reorganizations that lead to channel opening and subsequent membrane depolarization. Because of their role, pLGICs are involved in a wide range of diseases and disorders and are therefore important drug targets. A typical pLGIC is composed of a β -sheet rich extracellular domain (ECD) where ligand binding takes place, a transmembrane domain that is composed of four α-helices (TM1-TM4). In vertebrates pLGICs often contain a third intracellular domain (ICD), located between TM3 and TM4. The 5-HT3R is active as a homopentameric receptor of five identical A subunits, or as a heteropentamer containing one or more of several subunits (B to E) together with an A subunit. The 5-HT3 receptor is naturally located in the cell membrane in low amounts. For in vitro experiments such as biophysical investigation, the receptor has to be overproduced and purified in a detergent-solubilized state. Therefore, a robust and scalable expression system for homo- and heteropentameric 5-HT3 receptors was developed, building upon a tetracycline inducible cell line and Strep-tag affinity purification technology. Production of solubilized and purified 5-HT3R is well suited for use in the structural and functional characterization of the receptor. The stability of the 5-HT3 receptor is an important parameter during structural and functional experimentation. Using thermal unfolding the stability of 5-HT3R was investigated in plasma membranes as well as during detergent-extraction, purification and reconstitution into artificial lipid bilayers. A large loss in thermostability was found that correlates with the loss of the lipid bilayer during membrane solubilization and purification. Thermal unfolding of 5-HT3R occurred in consecutive steps at distinct protein locations: First a loss of ligand binding is detected, followed by formation of different transient low oligomeric states of receptor pentamers, followed by partial unfolding of helical parts of the protein, which finally leads to the formation large receptor aggregates. It was also found that structural destabilization of the receptor in detergents could be partially reversed by reconstituting the receptor into lipid bilayers. Thermal unfolding leads to the irreversible formation of aggregates which is known to prevent effective refolding. Therefore, an further investigation of 5-HT3R was made by unfolding the receptor in urea and sodium dodecyl sulfate (SDS). The results indicate iii iv ABSTRACT that, unlike thermal unfolding, unfolding in urea and SDS does not result in the formation of aggregates. Unfolding by urea shows a 50% loss of helical content while keeping the characteristic pentamer intact. Contrastingly, unfolding by SDS shows dissociation of the pentamer, but no noticeable change in secondary structure. Still, refolding from urea and SDS proved to be impossible. Two weak fluorophores, crystal violet (CrV) and ethidium bromide (EtBr), bind to the homologous nicotinic acetylcholine receptor (nAChR). Because the fluorescence of these compounds is also sensitive towards their environment they can be used as a molecular beacon for the functional state of a receptor. When applied to 5-HT3R, it was found that CrV and EtBr bind with micromolar affinity to the desensitized state of the receptor – similar to binding reported for the nAChR. It appeared that binding of CrV or EtBr to the 5-HT3R induces a certain functional state (resting, open or desensitized). Because no detectable change in fluorescence occurs, this prevents their use as molecular beacons. Still, non-competitive binding to the 5-HT3R was little reported on before and could be an important target in pharmacological research. The ICD of the 5-HT3R is predicted to contain a stretch of ∼60 disordered or flexible residues which might be involved in subunit assembly and membrane trafficking. These unstructured regions of a 5-HT3R were probed using limited proteolysis. Thereby two distinct fragments were formed that remain tightly associated with each other, while a small stretch of 35 residues between TM3 and TM4 was removed. Furthermore, it was shown that the thermal stability of the helical core is unchanged compared to untreated 5-HT3R, but that the extracellular ligand-binding domain is very sensitive to cleavage in the ICD. By probing the 5-HT3R with limited proteolysis a rigid core was identified, indicating the important role of the transmembrane domain for holding together the pLGIC scaffold. The results presented here contribute a significant body of knowledge to membrane proteins in general and to the 5-HT3 receptor in particular, upon which further research can be based leading to advances in the fields of biochemistry, biophysics and pharmacology.

EPFL2012

The role of TIF1 gamma during adult murine hematopoiesis

Konstantin Shakhbazov

EPFL2009

EPFL2012