Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Studies of protein-protein interaction using countercurrent distribution in aqueous two-phase systems. Partition behaviour of six Calvin-cycle enzymes from a crude spinach (Spinacia oleracea) chloroplast extract.

ABSTRACT: The partition behaviour of six enzymes of the Calvin cycle in extracts of chloroplasts from spinach (Spinacia oleracea) between two aqueous phases has been studied by countercurrent distribution. The enzymes showed distribution patterns which indicate heterogeneity and the presence of two or three fractions of most of the enzymes. When two of the enzymes, phosphoglycerate kinase and fructose-bisphosphate aldolase, were partitioned in both purified and partially purified form, they behaved like homogeneous substances. These results indicate that countercurrent distribution of crude extracts in aqueous two-phase systems is a useful method to study protein-protein interaction.

SUBMITTER: Persson LO

PROVIDER: S-EPMC1138596 | biostudies-other | 1989 May

REPOSITORIES: biostudies-other

ACCESS DATA

Json Xml

Similar Datasets

Action of calcium ions on spinach (Spinacia oleracea) chloroplast fructose bisphosphatase and other enzymes of the Calvin cycle.

Project description:Thiol-treated spinach (Spinacia oleracea) chloroplast fructose bisphosphatase is powerfully inhibited by Ca2+ non-competitively with respect to its substrate, fructose 1,6-bisphosphate. 500 microM-Ca2+ causes virtually complete inhibition and the Ki is 40 microM. Severe inhibition of sedoheptulose bisphosphatase is also caused by Ca2+. A role for Ca2+ in regulation of the Calvin cycle in spinach chloroplasts is proposed.

| S-EPMC1161961 | biostudies-other

Effect of hydrogen peroxide on spinach (Spinacia oleracea) chloroplast fructose bisphosphatase.

Project description:Thiol-treated spinach (Spinacia oleracea) chloroplast fructose bisphosphatase (EC 3.1.3.11) is severely inhibited by H2O2, whereas the freshly purified enzyme is little affected. Dithiothreitol reverses inhibition by H2O2, indicating that essential thiol groups are oxidized during H2O2 inactivation. A new role for the dithiol and thioredoxin systems that are operative in illuminated chloroplasts is proposed.

| S-EPMC1162009 | biostudies-other

Stromal protein phosphorylation in spinach (Spinacia oleracea) chloroplasts.

Project description:When intact spinach chloroplasts were supplied with [32P]Pi, stromal protein phosphorylation was found to occur in the dark. On illumination the thylakoid protein kinase was activated and the amount of label found in thylakoid proteins quickly exceeded that incorporated into stromal protein, such that the latter was found to account for only 10-15% of the total radioactivity bound to chloroplast proteins after 5 min illumination. The rate of phosphorylation of stromal polypeptides was unchanged by light. After SDS/polyacrylamide-gel electrophoresis, more than 15 labelled polypeptides of stromal origin were observed. A polypeptide with an Mr of approx. 70 000 had the highest specific activity of labelling. Both the large and small subunits of the ribulose-1,5-bisphosphate carboxylase were phosphorylated. The level of phosphorylation of stromal protein was increased by CO2 fixation in intact chloroplasts. This increase was not observed in the absence of NaHCO3 or in the presence of the phosphoribulokinase inhibitor DL-glyceraldehyde. These effects appeared to be largely due to changes in the phosphorylation state of the large and small subunits of ribulose-1,5-bisphosphate carboxylase. Studies with the reconstituted chloroplast system showed that the thylakoid protein kinase(s) played no part in the phosphorylation of stromal protein. The rate and level of phosphorylation of stromal protein was unaffected by the activation state of the thylakoid protein kinase and was unchanged when thylakoids were omitted from the reaction medium. The phosphorylation of stromal proteins is therefore catalysed by a discrete soluble protein kinase.

| S-EPMC1152708 | biostudies-other

pH and kinetic studies of chloroplast sedoheptulose-1,7-bisphosphatase from spinach (Spinacia oleracea).

Project description:The aim of this paper is to study some steady-state kinetic properties of sedoheptulose-1,7-bisphosphatase, its pH-dependence and the effect of a substrate analogue, fructose 2,6-bisphosphate. Studies were carried out with sedoheptulose 1,7-bisphosphate and with fructose 1,6-bisphosphate, an alternative substrate. The pK values are identical for both substrates, and fructose 2,6-bisphosphate behaves like a competitive inhibitor. These results suggest that there exists a unique active site for either sedoheptulose 1,7-bisphosphate or fructose 1,6-bisphosphate on the enzyme molecule. Increasing Mg2+ concentrations shifted the optimum pH. As for fructose-1,6-bisphosphatase, we believe that this shift is due to the neutralization of negative charges near the active centre [Cadet, Meunier & Ferté (1987) Eur. J. Biochem. 162, 393-398]. The free species of sedoheptulose 1,7-bisphosphate and fructose 1,6-bisphosphate are not the usual substrates of enzyme, nor is Mg2+. But the kinetics relative to the (Mg2+-substrate4-)2- complex is not consistent with this complex being the substrate. An explanation of this discrepancy is proposed, involving both the negative charges near the active centre and the positive charges of Mg2+. The observed Vmax. of the reduced enzyme is 65% of the theoretical Vmax. for both substrates, but the observed Vmax. relative to sedoheptulose 1,7-bisphosphate is 3 times the one relative to fructose 1,6-bisphosphate. The specificity constant (kcat./Km), 1.62 x 10(6) M-1.s-1 with respect to sedoheptulose 1,7-bisphosphate compared with 5.5 x 10(4) M-1.s-1 with respect to fructose 1,6-bisphosphate, indicates that the enzyme specificity towards sedoheptulose 1,7-bisphosphate is high but not absolute.

| S-EPMC1149282 | biostudies-other

Spinacia oleracea strain:Spinach

Project description:Spinacia oleracea strain:Spinach Raw sequence reads

| PRJNA576552 | ENA

The complete mitochondrial genome sequence of spinach, <i>Spinacia oleracea</i> L.

Project description:Spinach (Spinacia oleracea L.) is an economically important vegetable crop. Here we describe the complete mitochondrial DNA sequence of spinach, which has a length of 329,613 bp and a GC content of 43.4%. It is separated by a pair of directly repeated elements of 7286 bp, to form a large single copy region of 229,375 bp and a small single copy region of 85,666 bp. The genome contains 29 protein-coding genes, 4 pseudogenes, 24 tRNA genes, and 3 rRNA genes. A phylogenetic analysis revealed that spinach was closely related to Beta vulgaris (sugar beet), both belonging to the Amaranthaceae family.

| S-EPMC7799700 | biostudies-literature

Heat-induced alternations in proteomic and transcriptomic profiles of spinach (Spinacia oleracea)

Project description:Spinach (Spinacia oleracea L.) is an economically important and globally consumed popular leafy vegetable that is heat-sensitive. Heat stress caused by global climate change is one of the primary deleterious elements limiting spinach production worldwide. Little work has been done to explore the heat-responsive mechanisms of spinach under high temperature-induced stress. In the present study, we used iTRAQ-based proteomic and transcriptomic approaches to investigate physiological, metabolic, and proteomic responses of spinach in response to day / night temperature of 35°C / 25°C compared to 20°C / 15°C for 4 days. A total of 3,543 differentially expressed genes (DEGs) were detected using transcriptome sequencing, of which 2,086 DEGs were downregulated and 1,457 were upregulated. The DEGs were mainly involved in superoxide dismutase activity, catalase, and peroxidase activity. A total of 3,246 differentially abundant proteins were detected using iTAQ-based quantitative proteomic approach, from which 567 differentially expressed proteins (DEPs) (277 upregulated and 290 downregulated) were identified. DEPs were mainly assigned to pathways related to metabolism, signal transduction, protein degradation, defense, and antioxidant. Four genes - superoxide dismutase (SOD, LOC110788339), catalase (CAT, LOC110790286), peroxidase (POD, LOC110775253), and heat shock protein (HSP, LOC110799288) - were validated using quantitative real-time PCR (qRT-PCR) to verify the proteomic and transcriptomic analyses, showing different transcriptional and translational expression levels. The findings of this study provide a fundamental understanding of the metabolic pathways and biological processes that control adaptation to heat stress in spinach, and provide novel insight into the development of heat-tolerant spinach.

2020-06-24 | GSE153070 | GEO

Direct desaturation of intact galactolipids by a desaturase solubilized from spinach (Spinacia oleracea) chloroplast envelopes.

Project description:In plants, polyenoic fatty acids are synthesized by desaturase enzymes which use acyl groups of membrane lipids as substrates. To provide direct 'in vitro' evidence for this reaction, we solubilized envelope membranes from spinach (Spinacia oleracea) chloroplasts with Triton X-100 to release a membrane-bound n-6 desaturase. In the presence of oxygen and reduced ferredoxin, the solubilized enzyme desaturated a variety of substrates, such as free oleic acid, free erucic acid, 1-oleoyl-sn-glycerol 3-phosphate and the three galactolipids 1-oleoyl-2-(7'-cis-hexadecenoyl)-3-beta-D-galactopyranosyl-sn-glycerol, 1,2-dioleoyl-3-beta-D-galactopyranosyl-sn-glycerol and the ether analogue 1,2-di-(9'-cis-octadecenyl)-3-beta-D-galactopyranosyl-sn- glycerol. The in vitro desaturation of these exogenously added complex lipids with ester- and ether-linked substrate chains is unambiguous evidence for lipid-linked desaturation. The enzyme measures the insertion of the new double bond from the methyl end and the existing (n-9)-cis-double bond of an appropriate acyl or alkyl chain. The distal part of the substrate group, normally the carboxy end of a fatty acyl residue, is of less importance and, in particular, its activation in thioester form is not required.

| S-EPMC1132243 | biostudies-other

Properties of oxidized and reduced spinach (Spinacia oleracea) chloroplast fructose-1,6-bisphosphatase activated by various agents.

Project description:Fructose-1,6-bisphosphatase (FBPase) can be reduced and activated by either dithiothreitol or reduced thioredoxin. This activation is pH-dependent. An amino acid group with a pK value of 5.55 is involved in this process. Both enzyme forms can also be stimulated by agents such as fructose 1,6-bisphosphate, Mg2+, Ca2+ and Ca2+/fructose 1,6-bisphosphate. FBPase reduced by dithiothreitol is more strongly activated than the enzyme reduced by thioredoxin. The specificity constant (kcat./Km) is enhanced over 2.5-25-fold and 1.5-2-fold (depending on the agent used) for FBPase reduced by dithiothreitol and thioredoxin respectively. In both cases, no new kinetic properties appeared. The pH-activity profile of the stimulated enzyme is slightly shifted towards the acidic side with respect to the reduced enzyme. A lag phase is observed in the progress curve of both enzymic forms, treated or untreated. Each agent used to stimulate must induce a new conformation of the enzyme, more active than the initial one, characterized by a specificity constant and a relaxation time. This lag phase tends to disappear when the assay temperature is increased. Temperature has the same effect on the activity of oxidized, reduced and stimulated FBPase, but different effects on the stability of the different forms.

| S-EPMC1151415 | biostudies-other

Minor alleles are associated with white rust (Albugo occidentalis) susceptibility in spinach (Spinacia oleracea).

Project description:Minor alleles (MA) have been associated with disease incidence in human studies, enabling the identification of diagnostic risk factors for various diseases. However, allelic mapping has rarely been performed in plant systems. The goal of this study was to determine whether a difference in MA prevalence is a strong enough risk factor to indicate a likely significant difference in disease resistance against white rust (WR; Albugo occidentalis) in spinach (Spinacia oleracea). We used WR disease severity ratings (WR-DSRs) in a diversity panel of 267 spinach accessions to define resistant- and susceptibility-associated groups within the distribution scores and then tested the single-nucleotide polymorphism (SNP) variants to interrogate the MA prevalence in the most susceptible (MS) vs. most resistant (MR) individuals using permutation-based allelic association tests. A total of 448 minor alleles associated with WR severity were identified in the comparison between the 25% MS and the 25% MR accessions, while the MA were generally similar between the two halves of the interquartile range. The minor alleles in the MS group were distributed across all six chromosomes and made up ~71% of the markers that were also strongly associated with WR in parallel performed genome-wide association study. These results indicate that susceptibility may be highly determined by the disproportionate overrepresentation of minor alleles, which could be used to select for resistant plants. Furthermore, by focusing on the distribution tails, allelic mapping could be used to identify plant markers associated with quantitative traits on the most informative segments of the phenotypic distribution.

| S-EPMC6885047 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

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