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PubMed2003

[Iodoacetic acid as a potential elicitor of increased production of flavonoids in a culture of Ononis arvensis L. in vitro].

The paper tested the effect of iodoacetic acid in four different concentrations on the production of flavonoids in the callus and suspension culture of Ononis arvensis L. The elicitor was in contact with the culture for a period of 6; 24; 47; 72, and 168 hours. The obtained results show a statistically significant increase in the content of flavonoids in the suspension culture in comparison with the control in the use of all tested concentrations of the elicitor after 6; 24; 48, and 72 hours of elicitation. The maximal increase by 586% in the production of flavonoids in the suspension culture took place with the use of iodoacetic acid in a concentration of 1 mg/l. In the callus culture, the maximal increase in the formation of flavonoids occurred with the use iodoacetic acid in a concentration of 10 mg/l after 24 hours of elicitation, the content of flavonoids being increased by 529% in comparison with the control.

Culture Techniques↗
PubMed1987

Peroxidative membrane damage in human erythrocytes induced by a concerted action of iodoacetate, vanadate and ferricyanide.

Human erythrocytes incubated without substrate in the presence of iodoacetate (0.2 mM), vanadate (0.5 mM) and ferricyanide (5 mM) form aqueous membrane leaks of equivalent radii of 0.5-0.8 nm leading to complete colloid-osmotic lysis within 180 min. All three components are indispensable for the effect. Inosine but not glucose markedly enhances the rate of hemolysis. These effects are due to oxidative damage, as indicated by concomitant destruction of polyunsaturated fatty acids and suppression of both effects by radical scavengers. Hemoglobin is not oxidized under these conditions. GSH and membrane SH levels remain almost normal, and no crosslinking or irreversible aggregation of membrane proteins is observed. In the absence of O2 no membrane damage can be observed. It is proposed that radical formation originates from reduction of O2 by NADPH, analogous to processes described in microsomal membranes. NADH seems not to be involved, since leak formation occurs in spite of the blockage of NADH formation by iodoacetate. Vanadate and ferricyanide are probably required to amplify the peroxidative reaction sufficiently to overcome the cellular antioxidative capacity.

Erythrocyte Membrane↗
PubMed1991

Mesocestoides corti: a GC/MS study of the effects of oxaloacetate and iodoacetate on the isotope ratios in succinate and lactate excreted in the presence of NaH13CO3.

The current study was undertaken to gain further insight into the carbohydrate metabolism of the proliferating larvae of Mesocestoides corti by studying the effect of the metabolic inhibitors oxaloacetate and iodoacetate on the incorporation of label from NaH13CO3 into the excretory products lactate and succinate. These products were converted to their methyl derivatives and analyzed by gas chromatography/mass spectrometry (GC/MS) to determine the isotope ratios. The percentage of [1-13C]lactate, [1-13C]succinate, and [1,4-13C2]succinate decreased in the presence of oxaloacetate; iodoacetate did not significantly influence the relative amount of the former, but markedly increased percentages of the latter two. The data provide information on the relative rates of the pathways and steps within them and the influence of the inhibitors on these pathways.

Animals↗
PubMed1985

Sympathetic neurons extend neurites in a culture medium containing cyanide and dinitrophenol but not iodoacetate.

A culture medium circulated through the rat heart and supplemented with insulin, transferrin and nerve growth factor leads to a massive proliferation of neurite outgrowth from neurons of peripheral sympathetic ganglia of the chick embryo. Addition of 1 mM cyanide or 50 microM dinitrophenol to such medium for 2 days had no adverse effect on the neurite outgrowth and ATP content of these neurons. However, 0.5 microM iodoacetate lowered ATP content 65% without affecting the number of surviving neurons up to 2 days. Only when ATP content was reduced to 80% by 2.5 microM iodoacetate was the number of surviving neurons significantly reduced (30%). It is concluded that the glycolytic pathway is the major route of ATP synthesis in embryonic sympathetic neurons maintained in culture, and only a small fraction of ATP is utilized for the survival and neurite extension.

2,4-Dinitrophenol↗
PubMed1995

Conjugation to preactivated proteins using divinylsulfone and iodoacetic acid.

Two methods for the preactivation of proteins and conjugation of peptides to proteins under mild conditions are presented. Preactivation of proteins with divinylsulfone (DVS) permits peptide conjugation through either amino, hydroxyl or sulphydryl groups depending on the coupling pH used, while preactivation with iodoacetic acid (IAA) N-hydroxy-succinimide ester permits selective conjugation through sulphydryl groups. In addition, the latter method allows quantitation of the conjugation ratio through determination of carboxymethyl cysteine after acid hydrolysis. The divinylsulfone activated proteins can be stored for extended periods of time at -20 degrees C until required for conjugation, while the iodoacetic acid activated protein can be stored for a few days at -20 degrees C. These conjugation methods were investigated with respect to obtaining peptide/protein conjugates for immunization purposes and for use as reagents in immunoassays. The DVS activated proteins permitted direct conjugation of luteinizing releasing hormone (LHRH) through its tyrosine side chain and allowed synthesis of well defined conjugates. The DVS derivatives of bovine serum albumin (BSA), reduced and carboxymethylated BSA and purified protein derivative (PPD) were compared with respect to their potential value as carriers for obtaining antibodies to LHRH (M(r) 1000) and epidermal growth factor (EGF, M(r) 5000). IAA-PPD was evaluated as a carrier for the conjugation of glutathione specifically through its cysteine side chain and for obtaining antibodies to glutathione. The antisera obtained were specific and of high titer, and the methods described here will thus allow the convenient synthesis of carrier conjugates with well defined characteristics.

Amines↗
PubMed1991

Micropuncture study of the kidney in sheep: effects of iodoacetate on renal urea handling.

1. The effects of intrarenal infusion of iodoacetate, an inhibitor of anaerobic glycolysis, on urea transport in kidney of sheep was studied by micropuncture free-flow technique. 2. Iodoacetate decreased the tubular fluid to plasma urea ratio in late distal tubules only; no changes were found in both the late proximal and early distal tubules. Fractional delivery of urea to the same superficial segments of nephron and the urea excretion by whole kidney were not significantly influenced. 3. Our results do not support the concept of active urea transport in the kidney of sheep which would be dependent on energy derived from anaerobic metabolism.

Animals↗
PubMed1997

Different efficacy of iodoacetic acid and N-ethylmaleimide in high-performance liquid chromatographic measurement of liver glutathione.

The widely used high-performance liquid chromatography (HPLC) procedure to determine glutathione in biological samples utilizing iodoacetic acid as thiol quenching agent and 1-fluoro-2,4-dinitrobenzene for derivatization has been modified regarding tissue sample processing and storage of the working solutions. The modified procedure compared with the original method reduces artifactual oxidation in rat liver glutathione measurement (1.47+/-0.8% vs. 2.84+/-0.69%, respectively). In both HPLC procedures, an increase in artifactual oxidation was found in both standard glutathione solutions and hepatic samples when N-ethylmaleimide instead of iodoacetic acid was used for thiol trapping.

Animals↗
PubMed1986

Selective carboxymethylation of cysteine-174 of the beta 2 beta 2 and beta 1 beta 1 human liver alcohol dehydrogenase isoenzymes by iodoacetate.

The beta 1 beta 1 and beta 2 beta 2 human liver alcohol dehydrogenase isoenzymes differ by only one residue at the coenzyme-binding site; Arg-47 in beta 1 is replaced by His in the beta 2 subunit. Since Arg-47 is thought to facilitate the carboxymethylation of Cys-46 in horse liver alcohol dehydrogenase by binding halo acids in a Michaelis-Menten complex prior to inactivation, the specificity and kinetics of modification of the two human liver beta beta isoenzymes with iodoacetate were compared. Both of the beta beta isoenzymes were inactivated by treatment with iodo[14C]acetate, and one Cys per subunit was carboxymethylated. Cys-174, which is a ligand to the active-site zinc atom in horse liver alcohol dehydrogenase, was selectively carboxymethylated in each of the human beta beta isoenzymes; less than 15% of the iodo[14C]acetate incorporated into the enzyme appeared in Cys-46. Therefore, the three-dimensional structure of the basic amino acids in the anion-binding site of the human beta beta isoenzymes appears to be different from that of horse liver alcohol dehydrogenase. The kinetics of alkylation are consistent with the formation of a Michaelis-Menten complex before inactivation of the isoenzymes. The average Ki values for iodoacetate were 10 and 16 mM for beta 1 beta 1 and beta 2 beta 2, respectively, and maximal rate constants for inactivation were 0.22 and 0.17 min-1, respectively. From these data, it can be concluded that there is a relatively minor effect of the substitution of His for Arg at position 47 on the kinetics of inactivation.

Alcohol Dehydrogenase↗
PubMed1987

31P NMR saturation-transfer measurements in Saccharomyces cerevisiae: characterization of phosphate exchange reactions by iodoacetate and antimycin A inhibition.

31P nuclear magnetic resonance (NMR) saturation-transfer (ST) techniques have been used to measure steady-state flows through phosphate-adenosine 5'-triphosphate (ATP) exchange reactions in glucose-grown derepressed yeast. Our results have revealed that the reactions catalyzed by glyceraldehyde-3-phosphate dehydrogenase/phosphoglycerate kinase (GAPDH/PGK) and by the mitochondrial ATPase contribute to the observed ST. Contributions from these reactions were evaluated by performing ST studies under various metabolic conditions in the presence and absence of either iodoacetate, a specific inhibitor of GAPDH, or the respiratory chain inhibitor antimycin A. Intracellular phosphate (Pi) longitudinal relaxation times were determined by performing inversion recovery experiments during steady-state ATP gamma saturation and were used in combination with ST data to determine Pi consumption rates. 13C NMR and O2 electrode measurements were also conducted to monitor changes in rates of glucose consumption and O2 consumption, respectively, under the various metabolic conditions examined. Our results suggest that GAPDH/PGK-catalyzed Pi-ATP exchange is responsible for antimycin-resistant saturation transfer observed in anaerobic and aerobic glucose-fed yeast. Kinetics through GAPDH/PGK were found to depend on metabolic conditions. The coupled system appears to operate in a unidirectional manner during anaerobic glucose metabolism and bidirectionally when the cells are respiring on exogenously supplied ethanol. Additionally, mitochondrial ATPase activity appears to be responsible for the transfer observed in iodoacetate-treated aerobic cells supplied with either glucose or ethanol, with synthesis of ATP occurring unidirectionally.

Adenosine Triphosphate↗
PubMed1981

Cytoplasmic estrogen receptor system of gilt uterus. Partial purification of component B labeled with [14C]iodoacetic acid.

Analysis of the cytoplasmic estrogen receptor (ER) system of gilt uterus by protecting ER from proteolysis showed that the ER system of gilt uterus is similar to that of cow uterus described previously. There was only one native unit molecule [native "4S" ER (sedimentation coefficient, 4.5S; Stokes radius, 45 A; molecular weight, 82,000)] with specific affinity towards estradiol. This molecule was further designated as vero-ER. "8S" ER-forming factor [("8S"ER)-FF] (Stokes radius, 51 A) was separated from the cytosol under hypotonic (low salt) conditions, and this was further dissociated into component A ["5S" ER-forming factor, ("5S"ER)-FF] (Stokes radius, 37 A) and component B (Stokes radius, 18.5 A) in the presence of sodium thiocyanate. Vero-ER was proteolyzed in the absence of Ca2+ ion by a cytoplasmic protease into modified "4S" ER (sedimentation coefficient, 4.5S; Stokes radius, 35 A; molecular weight, 65,000) which was further designated as secto-ER. The constituents of the cytoplasmic ER system of cow and gilt uteri cross-reacted with each other to undergo similar molecular assembly as in their own systems. When analyzed for various uterine specimens, fluctuation of ("8S"ER)-FF-level (1-50 unit/g tissue) was more remarkable than that of ER-level (3-6 x (10(-12) mol/g tissue). Component B labeled with [14C]iodoacetic acid was purified over 1,500-fold. Mixture of vero-ER and component B labeled with [14C]iodoacetic acid formed "6S' ER with 14C-activities under hypotonic conditions. This clearly excluded the possibility that component B is a catalyzer of self-association (dimerization) of vero-ER.

Animals↗
PubMed1981

Alkylation of a ribonuclease from Streptomyces erythreus with iodoacetate and iodoacetamide.

1. RNase St was inactivated by iodoacetate. The inactivation was most rapid at pH 5.0-7.0. Competitive inhibitors protected RNase St from inactivation by iodoacetate. The protective effect of 2'-GMP was most effective among nucleotides tested. 2. RNase St was inactivated with the concomitant incorporation of one molar equivalent of carboxymethyl group. The carboxymethyl group incorporated into RNase St was liberated by treatment with 0.2 N NaOH or 1 M hydroxylamine. Thus the incorporation of a carboxymethyl group into a carboxyl group was demonstrated. 3. 14C-labeled CM-RNase St was digested successively with alkaline protease and aminopeptidase M. The 14C-labeled amino acid was identified as the carboxymethyl ester of glutamic acid by means of column chromatography. 4. By digestion of reduced carboxymethylated CM-RNase St with trypsin, a peptide containing a 14C-carboxymethyl group was isolated by Dowex AG-50W colum chromatography. alpha-Chymotryptic digestion of the radioactive tryptic peptide, Glu48-Lys65, produced a tetrapeptide containing a 14C-carboxymethyl group, that is, Tyr59-His60-Glu61-Tyr62. Therefore, it was concluded that Glu61 in RNase St was the site of carboxymethylation. 5. When RNase St was inactivated by iodoacetamide at pH 8.0, about 2 histidine residues were modified. The molar ratio of the products of carboxyamidomethylation were 52.3%, 21.7%, 21.0%, and 4.8% for 3-CAM-His, 1,3-di-CAM-His, 1-CAM-His, and di-CM-Lys, respectively. 6. CD spectra of CM-RNase St and CAM-RNase St were practically the same as that of the native RNase St indicating the maintenance of the native conformation during modification. 7. The binding constants of CM-RNase St and CAM-RNase St with 2'-GMP were about 1/150 and 1/38 of that of the native enzyme, respectively.

Alkylation↗
PubMed1988

[Perifusion of monolayer-cultured B cells of the infant rat: a comparative study of the effects of 2-deoxy-2-fluoroglucose and iodoacetic acid].

Cell culture techniques for monolayer islets of 3-week-old rat pancreases and the responsiveness of B cells are described. In this procedure, whole pancreatic tissues from 3-week-old rats were enzymatically dispersed and then cultured in a medium with 5.5 mM glucose plus 1 mM 2-deoxy-2-fluoroglucose or with 5.5 mM glucose following a 3-day exposure to a medium with 5.5mM glucose plus 5 microM iodoacetic acid. The use of 2-deoxy-2-fluoroglucose or iodoacetic acid allowed a selective deletion of fibroblasts, yielding large clusters that consisted mostly of islet cells. The immunocytochemical evaluation of the islet cells in these cultures showed that approximately 70% are B-cells, 20% A-cells, and 10% D-cells. On day 0, the response to 16.7 mM glucose included only a small rise in insulin secreted during the first and the second phase, and the response to 10 mM of leucine or 2-ketoisocaproate was monophasic. After being cultured for 7 days, all three secretagogues markedly stimulated insulin secretion by B cells cultured in both media, resulting in an enhancement of the biphasic pattern. However, quantitative relationships differed. Thus, the total response from B cells in 2-deoxy-2-fluoroglucose during a 30-min stimulation with glucose and leucine was significantly higher (1.6- and 1.9-fold respectively) than that from B cells in 5.5 mM glucose, although there was no significant difference in insulin secretion evoked by 2-ketoisocaproate. Furthermore, in the former B cells, the amount of insulin secreted during the second phase was 84-94% of the total insulin secretion, and in the latter it was 66-76%. Addition of 1 mM 3-isobutyl-1-methylxanthine and 10 microM forskolin resulted in a significant increase in insulin secretion by B cells in 2-deoxy-2-fluoroglucose, whereas there was no difference in the increase of insulin secretion induced by 16.7 mM glucose and 200 nM 12-o-tetradecanoyl phorbol-13-acetate. In monolayer cultures that had been maintained in both media for 15 days, the second phase of insulin secretion due to the secretagogues was slightly decreased, but the biphasicity in the response was well preserved. In conclusion, the present results suggest that B cells of 3-week-old rats may be still immature, and that the medium with 2-deoxy-2-fluoroglucose is beneficial to the continued maturation of the B-cell function in vitro.

Animals↗
PubMed1992

[A biochemical study of an animal model with defective muscle glycolysis, induced by iodoacetate administration].

A rat model produced by intraaortic injection of sodium iodoacetate was analyzed biochemically. Hind leg muscles obtained from iodoacetate-injected site showed a selective inhibition of the glyceraldehyde-3-phosphate dehydrogenase (G3PD) activity less than 10% of control mean. No loss of mitochondrial enzyme activity was observed. Electrical stimulation at the sciatic nerve revealed muscle contractures and this muscle showed a mild degeneration in histochemically. This study indicates that this model will be useful to study the pathophysiology of human muscle glycogen storage diseases.

Animals↗
PubMed1981

Effects of iodoacetic acid on relaxation parameters of the rabbit papillary muscle.

Measurements have been made of isometric contractions and diastolic oscillations (after-contractions) in right ventricular rabbit papillary muscles at a temperature of 14.5 degrees C. The relaxation courses can be described as damped harmonic oscillations superposed on an exponential descending carrier function by using a model with six parameters. The influence of iodoacetic acid (10(-4) M) was investigated on contraction and relaxation parameters which result from approximation of the measured force values. The following changes were observed: 1. Decrease of the contraction height as well as of the amplitudes of diastolic oscillations. 2. Increase in the damping ratio and in the period of diastolic oscillations both calculated from relaxation parameters. 3. Diminution of the force range which is passed by the carrier function within 6 s of relaxation time accompanied by a transition to contracture. A fast and a slow Ca sequestration process are supposed to exist. The results indicate that both of them are influenced by iodoacetic acid.

Animals↗
PubMed2004

Phospholipase C is involved in the adenosine-activated signal transduction pathway conferring protection against iodoacetic acid-induced injury in primary rat neuronal cultures.

We have demonstrated before that exposure of neuronal cultures to poisoning by iodoacetic acid, followed by "reperfusion" (iodoacetate-"reperfusion" insult; IAA-R insult), results in severe cytotoxicity. This insult was found to be associated with ATP depletion and generation of reactive oxygen species. The cultured neurons could be protected against the insult by activation of the adenosine A1 receptors and by presence of antioxidants. Previous studies in our laboratory demonstrated that the adenosine-activated signal transduction pathway (Ado-STP) conferring protection against the IAA-R insult, involves activation of protein kinase C-epsilon (PKCepsilon) and opening of ATP sensitive potassium (K(ATP)) channels. In this respect, the adenosine-activated protective mechanism against the IAA-R insult is similar to the Ado-STP in the neurons and in cardiomyocytes against ischemia-reperfusion injury. Phospholipase C (PLC) is an additional component demonstrated recently to participate in the myocardial Ado-STP protecting against ischemia-reperfusion. Here we provide proof for the involvement of PLC also in the neuronal Ado-STP protecting against the IAA-R insult. Primary rat neuronal cultures were exposed to the IAA-R insult. The neurons could be protected against this insult by activation of the adenosine A1 receptors by N6-(R)-phenylisopropyladenosine (R-PIA), a specific A1 adenosine receptor agonist. Exposure of the cultures to the PLC inhibitor U73122, abrogated the protection. The exposure of the cultures to R-PIA was found to enhance PLC activity, an effect that could be abrogated by presence of U73122. The R-PIA-induced increase in PLC activity was short-lived, in the range of minutes. These results demonstrate that activation of PLC is a vital step in the neuronal protective Ado-STP, but that it does not contribute directly to the relatively long time window of the protection signal shown previously to characterize the neuronal mechanism. The results also support the suggestion that the Ado-STP protecting against the IAA-R insult and that protecting against ischemia-reperfusion may represent the same mechanism.

Adenosine↗
PubMed1959

The creatine phosphoryltransfer reaction in iodoacetate-poisoned muscle.

The iodoacetate-nitrogen-poisoned muscle offers the possibility of studying the stoichiometry of the single muscle twitch since metabolic resynthesis by glycolysis and oxidative phosphorylation are blocked, and there remains as an energy source only the creatine phosphoryltransfer system, creatine phosphate reacting with adenosinediphosphate to give the triphosphate and creatine. It is shown, preparatory to a determination of the amount of phosphocreatine split in a single twitch, that iodoacetate does not inhibit creatine phosphoryltransferase at concentrations which block glycolysis. An analysis is developed which assumes that the transferase maintains the creatine phosphoryl transfer reaction in equilibrium following contraction, and further that the creatine phosporyltransfer reaction and the myokinase reaction are isolated in muscle. On the basis of this analysis and the data obtained, an estimate of the equilibrium constant of the creatine phosphoryl reaction in muscle is obtained which agrees with values determined in vitro. Using the estimated equilibrium constant, and the concentrations of creatine, creatine phosphate, and adenosinetriphosphate found, a value for the concentration of free adenosinediphosphate is obtained which is considerably less than that found by direct chemical analysis.

Adenosine Diphosphate↗
PubMed1975

The structure of dihydrofolate reductase. Identification of methionine residues carboxymethylated by iodoacetate with loss of catalytic activity.

Dihydrofolate reductase from the amethopterin-resistant mutant (strain A) of Streptococcus faecium var. Durans was reacted with iodo[14C]acetate according to three procedures; (a) in the absence of an inhibitor, (b) in the presence of aminopterin, and (c) in absence of inhibitor, but after treatment with unlabeled iodoacetate in presence of aminopterin. The first and last procedures resulted in the loss of approximately 90% of the catalytic activity, whereas in the presence of aminopterin essentially no activity was lost. Peptides were produced from all three labeled proteins by tryptic digestion after citraconylation of the lysine residues. From the amino acid compositions and partial amino acid sequences of these peptides the position of all modified methionines in the sequence was determined. The extent of labeling at each methionine, in enzyme labeled in the different procedures, indicated that methionines 28 and 50 may be at the binding site for inhibitors and that residue 50 is less accessible to iodoacetate than is residue 28. It is likely that carboxymethylation of residue 28 is responsible for the loss of enzyme activity.

Aminopterin↗