Browse
Submit Data
Databases
API
Help

Dataset Information

19 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Kinetics and reaction mechanism of potassium-activated aldehyde dehydrogenase from Saccharomyces cerevisiae.

ABSTRACT: Data from steady-state kinetic analysis of yeast K+-activated aldehyde dehydrogenase are consistent with a ternary complex mechanism. Evidence from alternative substrate analysis and product-inhibition studies supports an ordered sequence of substrate binding in which NAD+ is the leading substrate. A preincubation requirement for NAD+ for maximum activity is also consistent with the importance of a binary enzyme-NAD+ complex. Dissociation constant for enzyme-NAD+ complex determined kinetically is in reasonable agreement with that determined by direct binding. The order of substrate addition proposed here differs from that proposed for a yeast aldehyde dehydrogenase previously reported. Different methods of purification produced an enzyme that showed similar kinetic characteristics to those reported here.

SUBMITTER: Bostian KA

PROVIDER: S-EPMC1185844 | biostudies-other | 1978 Sep

REPOSITORIES: biostudies-other

ACCESS DATA

Json Xml

Similar Datasets

Rapid purification and properties of potassium-activated aldehyde dehydrogenase from Saccharomyces cerevisiae.

Project description:A method for the purification of yeast K+-activated aldehyde dehydrogenase is presented which can be completed in substantially less time than other published procedures. The enzyme has a different N-terminal amino acid from preparations previously reported, and other small differences in amino acid content. These differences may be the result of differential proteolytic digestion rather than a different protein in vivo. A purification step involves the biospecific adsorption on affinity columns containing immobilized nucleotides in the absence of the substrate aldehyde. Direct binding studies with the coenzyme in the absence of aldehyde reveal 4 NAD sites per tetrameric molecule, each with a dissociation constant of 120 micron. These results conflict with properties of preparations previously reported and may conflict with kinetic models that have aldehyde as the leading substrate. Binding to Blue Dextran affinity columns suggests the presence of a dinucleotide fold in common with other dehydrogenases and kinases.

| S-EPMC1185843 | biostudies-other

The role of the metal ion in the mechanism of the K+-activated aldehyde dehydrogenase of Saccharomyces cerevisiae.

Project description:The effect of K+ on assays of the enzyme was studied and it appears that the activation occurs slowly by a two-step process. Kinetic measurements suggest that the enzyme-catalysed reaction can proceed slowly (0.4%) in the complete absence of K+. The enzyme exhibits a K+-activated esterase activity, which is further activated by NAD+ or NADH. Stopped-flow studies indicated that the principal effect of K+ on the dehydrogenase reaction is to accelerate a step (possibly acyl-enzyme hydrolysis) associated with a fluorescence and small absorbance transient that occurs after hydride transfer and before NADH dissociation from the terminal E-NADH complex. The variation of activity of the enzyme with pH was studied. An enzyme group with pKa approx. 7.1 apparently promotes enzyme activity when in its alkaline form.

| S-EPMC1148419 | biostudies-other

Bovine lens aldehyde dehydrogenase. Kinetics and mechanism.

Project description:Bovine lens cytoplasmic aldehyde dehydrogenase exhibits Michaelis-Menten kinetics with acetaldehyde, glyceraldehyde 3-phosphate, p-nitrobenzaldehyde, propionaldehyde, glycolaldehyde, glyceraldehyde, phenylacetylaldehyde and succinic semialdehyde as substrates. The enzyme was also active with malondialdehyde, and exhibited an esterase activity. Steady-state kinetic analyses show that the enzyme exhibits a compulsory-ordered ternary-complex mechanism with NAD+ binding before acetaldehyde. The enzyme was inhibited by disulfiram and by p-chloromercuribenzoate, and studies with with mercaptans indicated the involvement of thiol groups in catalysis.

| S-EPMC1152404 | biostudies-other

The purification and some properties of the Mg(2+)-activated cytosolic aldehyde dehydrogenase of Saccharomyces cerevisiae.

Project description:A purification procedure has been developed for the cytosolic aldehyde dehydrogenase of Saccharomyces cerevisiae that yields homogeneous enzyme. The enzyme seems to be a tetramer of identical 58 kDa subunits. The enzyme reaction is strongly stimulated by Mg2+ at low NADP+ concentrations but there is no absolute requirement for bivalent cations. The kinetics of the reaction have been studied in the presence and absence of MgCl2. NADP+ binding studies of the quenching of protein fluorescence in the presence and absence of MgCl2 show that the effect of Mg2+ is to increase the affinity of the enzyme for NADP+ by approx. 100-fold. NADP+ binding causes a slow conformational change in the enzyme and converts the enzyme from the inactive or low-activity form in which it is isolated into the fully active form. This conformational change seems to explain the marked lag-phases seen in enzyme assays. The enzyme is strongly inhibited by disulfiram and pyridoxal 5-phosphate.

| S-EPMC1217208 | biostudies-other

Aldehyde dehydrogenase, Ald4p, is a major component of mitochondrial fluorescent inclusion bodies in the yeast Saccharomyces cerevisiae.

Project description:When Saccharomyces cerevisiae strain 3626 was cultured to the stationary phase in a medium that contained glucose, needle-like structures that emitted autofluorescence were observed in almost all cells by fluorescence microscopy under UV excitation. The needle-like structures completely overlapped with the profile of straight elongated mitochondria. Therefore, these structures were designated as mitochondrial fluorescent inclusion bodies (MFIBs). The MFIB-enriched mitochondrial fractions were successfully isolated and 2D-gel electrophoresis revealed that a protein of 54 kDa was only highly concentrated in the fractions. Determination of the N-terminal amino acid sequence of the 54-kDa protein identified it as a mitochondrial aldehyde dehydrogenase, Ald4p. Immunofluorescence microscopy showed that anti-Ald4p antibody specifically stained MFIBs. Freeze-substitution electron microscopy demonstrated that cells that retained MFIBs had electron-dense filamentous structures with a diameter of 10 nm in straight elongated mitochondria. Immunoelectron microscopy showed that Ald4p was localized to the electron-dense filamentous structures in mitochondria. These results together showed that a major component of MFIBs is Ald4p. In addition, we demonstrate that MFIBs are common features that appear in mitochondria of many species of yeast.

| S-EPMC4021361 | biostudies-literature

Heterologous Expression of Aldehyde Dehydrogenase from Saccharomyces cerevisiae in Klebsiella pneumoniae for 3-Hydroxypropionic Acid Production from Glycerol.

Project description:3-Hydroxypropionic acid (3-HP) is a commercially valuable platform compound. Klebsiella pneumoniae has been concerned as an appropriate host for 3-HP production because of its robust capacity to metabolize glycerol. Glycerol conversion to 3-HP in K. pneumoniae comprises two successive reactions: glycerol dehydratase catalyzes glycerol to 3-hydroxypropionaldehyde (3-HPA); aldehyde dehydrogenase catalyzes 3-HPA to 3-HP. Previous studies focusing on inducible expression of aldehyde dehydrogenase have shown defects of high cost of inducer and low catalytic activity due to inclusion body. Here we show a different strategy that a native promoter in the host K. pneumoniae was used to drive the heterologous expression of aldehyde dehydrogenase gene ald4 from Saccharomyces cerevisiae. The 3-HP yield of the recombinant reached a peak of 4.23 g/L at log phase, but it decreased during later period of fermentation. Except the validation of high activity of ald4, particularly, the 3-HP formation was uncovered to be closely coupled with cell division, and the lacking of NAD and ATP at latter fermentation phase became the bottleneck for cell growth and 3-HP accumulation. Furthermore, 3-HP is postulated to be converted to 3-HPA via feedback inhibition or other metabolite via unknown mechanism. Since glycerol dissimilation is a common mechanism in a variety of bacteria, the expression strategy using native promoter and implications may provide significant insight into the metabolic engineering for 3-HP production.

| S-EPMC3460132 | biostudies-literature

Kinetics of phosphomevalonate kinase from Saccharomyces cerevisiae.

Project description:The mevalonate-based isoprenoid biosynthetic pathway is responsible for producing cholesterol in humans and is used commercially to produce drugs, chemicals, and fuels. Heterologous expression of this pathway in Escherichia coli has enabled high-level production of the antimalarial drug artemisinin and the proposed biofuel bisabolane. Understanding the kinetics of the enzymes in the biosynthetic pathway is critical to optimize the pathway for high flux. We have characterized the kinetic parameters of phosphomevalonate kinase (PMK, EC 2.7.4.2) from Saccharomyces cerevisiae, a previously unstudied enzyme. An E. coli codon-optimized version of the S. cerevisiae gene was cloned into pET-52b+, then the C-terminal 6X His-tagged protein was expressed in E. coli BL21(DE3) and purified on a Ni²? column. The KM of the ATP binding site was determined to be 98.3 µM at 30°C, the optimal growth temperature for S. cerevisiae, and 74.3 µM at 37°C, the optimal growth temperature for E. coli. The K(M) of the mevalonate-5-phosphate binding site was determined to be 885 µM at 30°C and 880 µM at 37°C. The V(max) was determined to be 4.51 µmol/min/mg enzyme at 30°C and 5.33 µmol/min/mg enzyme at 37°C. PMK is Mg²? dependent, with maximal activity achieved at concentrations of 10 mM or greater. Maximum activity was observed at pH?=?7.2. PMK was not found to be substrate inhibited, nor feedback inhibited by FPP at concentrations up to 10 µM FPP.

| S-EPMC3903622 | biostudies-literature

Elucidating the reaction mechanism of the benzoate oxidation pathway encoded aldehyde dehydrogenase from Burkholderia xenovorans LB400.

Project description:Oxidation of cis-3,4-dehydroadipyl-CoA semialdehyde to cis-3,4-dehydroadipyl-CoA by the aldehyde dehydrogenase, ALDH(C) (EC.1.2.1.77), is an essential step in the metabolism of benzoate in Burkholderia xenovorans LB400. In a previous study, we established a structural blueprint for this novel group of ALDH enzymes. Here, we build significantly on this initial work and propose a detailed reaction mechanism for ALDH(C) based on comprehensive structural and functional investigations of active site residues. Kinetic analyses reveal essential roles for C296 as the nucleophile and E257 as the associated general base. Structural analyses of E257Q and C296A variants suggest a dynamic charge repulsion relationship between E257 and C296 that contributes to the inherent flexibility of E257 in the native enzyme, which is further regulated by E496 and E167. A proton relay network anchored by E496 and supported by E167 and K168 serves to reset E257 for the second catalytic step. We also propose that E167, which is unique to ALDH(C) and its homologs, serves a critical role in presenting the catalytic water to the newly reset E257 such that the enzyme can proceed with deacylation and product release. Collectively, the reaction mechanism proposed for ALDH(C) promotes a greater understanding of these novel ALDH enzymes, the ALDH super-family in general, and benzoate degradation in B. xenovorans LB400.

| S-EPMC3104234 | biostudies-literature

Determination of the Cytosolic NADPH/NADP Ratio in Saccharomyces cerevisiae using Shikimate Dehydrogenase as Sensor Reaction.

Project description:Eukaryotic metabolism is organised in complex networks of enzyme catalysed reactions which are distributed over different organelles. To quantify the compartmentalised reactions, quantitative measurements of relevant physiological variables in different compartments are needed, especially of cofactors. NADP(H) are critical components in cellular redox metabolism. Currently, available metabolite measurement methods allow whole cell measurements. Here a metabolite sensor based on a fast equilibrium reaction is introduced to monitor the cytosolic NADPH/NADP ratio in Saccharomyces cerevisiae: NADP + shikimate ⇄ NADPH + H(+) + dehydroshikimate. The cytosolic NADPH/NADP ratio was determined by measuring the shikimate and dehydroshikimate concentrations (by GC-MS/MS). The cytosolic NADPH/NADP ratio was determined under batch and chemostat (aerobic, glucose-limited, D = 0.1 h(-1)) conditions, to be 22.0 ± 2.6 and 15.6 ± 0.6, respectively. These ratios were much higher than the whole cell NADPH/NADP ratio (1.05 ± 0.08). In response to a glucose pulse, the cytosolic NADPH/NADP ratio first increased very rapidly and restored the steady state ratio after 3 minutes. In contrast to this dynamic observation, the whole cell NADPH/NADP ratio remained nearly constant. The novel cytosol NADPH/NADP measurements provide new insights into the thermodynamic driving forces for NADP(H)-dependent reactions, like amino acid synthesis, product pathways like fatty acid production or the mevalonate pathway.

| S-EPMC4525286 | biostudies-literature

Transcriptional response of Saccharomyces cerevisiae to potassium starvation.

Project description:BACKGROUND: Ion homeostasis is essential for every cell and aberrant cation homeostasis is related to diseases like Alzheimer's disease and epilepsy. The mechanisms responsible for cation homeostasis are only partly understood. The yeast Saccharomyces cerevisiae is an excellent organism to study fundamental aspects of cation homeostasis. In this study we investigated the transcriptional response of this yeast to potassium starvation by using Serial Analysis of Gene Expression (SAGE)-tag sequencing. RESULTS: Comparison of transcript levels in cells grown for 60 min in media without potassium with those in cells grown under standard potassium concentrations showed that the mRNA levels of 105 genes were significantly (P < 0.01) up-regulated more than 2.0-fold during potassium starvation and the mRNA levels of 172 genes significantly down-regulated. These genes belong to several functional categories. Genes involved in stress response including HSP30, YRO2 and TPO2 and phosphate metabolism including PHO84, PHO5 and SPL2 were highly up-regulated. Analysis of the promoter of PHO84 encoding a high affinity phosphate transporter, revealed that increased PHO84 RNA levels are caused by both increased Pho4-dependent transcription and decreased RNA turnover. In the latter process antisense transcription may be involved. Many genes involved in cell cycle control, and to a lesser extent genes involved in amino acid transport, were strongly down-regulated. CONCLUSIONS: Our study showed that yeast cells respond to potassium starvation in a complex way and reveals a direct link between potassium homeostasis and phosphate metabolism.

| S-EPMC4289377 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data