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PubMed1982

[Inhibition of cytochrome b2 by acrylamide].

Acrylamide (0.4--0.9 M) irreversibly inhibits reduced (Ered) cytochrome b2 (L (+) -lactate: cytochrome c oxidoreductase) from the yeast Hansenula anomala (ki = 1,67 min-1 at 35 degrees in 0.73 M solution of acrylamide). Changes in fluorescence of FMN, which reflect the changes in protein structure occur symbatically to the inactivation. The rate of inactivation depends on concentration of acrylamide in a degree of 6.4. The inactivation of the oxidized enzyme occurs faster than that of th reduced one at concentrations less than 0.5 M. The inactivation of Ered by acrylonitrile and acrylic acid occurs 10 times slower and does not correlate with the rate of mercaptoethanol binding to the monomers. The inhibition of Ered is caused by specific effects of carylamide and modification of the enzyme active center.

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PubMed2001

Protein alkylation by acrylamide, its N-substituted derivatives and cross-linkers and its relevance to proteomics: a matrix assisted laser desorption/ionization-time of flight-mass spectrometry study.

The present review highlights some important alkylation pathways of proteins, as measured by matrix assisted laser desorption/ionization-time of flight (MALDI-TOF)-mass spectrometric analysis, engendered by acrylamide and a number of its derivatives, including N-substituted acrylamides, cross-linkers and Immobilines (the acrylamido weak acids and bases used to create immobilized pH gradients). The present data are of relevance in two-dimensional maps and proteome analysis. It is shown that acrylamide can alkylate the -SH group of proteins even when engaged in disulfide bridges. An order of reactivity is obtained for a series of cross-linkers, which are shown to have an extremely reacting double bond, with the second one almost unreactive, originating "pendant, unreacted ends", which can subtract proteins migrating in a gel by covalently affixing them to it. An analogous reactivity scale is constructed also for the Immobiline chemicals, whose reactivity is shown to be linearly dependent on the pK values, the least reacting species being the acidic compounds. When analyzing real-life samples by two-dimensional (2-D) maps, like milk powders, a number of modifications can be detected by MALDI-TOF mass spectra of eluted spots, including variable phosphorylation sites (up to nine) and lactosyl moieties. If, for eluting such spots, formic acid is used, MALDI-TOF mass spectrometry (MS) reveals an incredible number of formylation sites, on Ser and Thr residues.

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PubMed2002

In situ alkylation with acrylamide for identification of cysteinyl residues in proteins during one- and two-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis.

Cysteinyl residues in proteins were alkylated with acrylamide during sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) to yield a thioether derivative, cys-S-beta-propionamide (PAM cys). The process was termed in situ alkylation with acrylamide. Using this method, the recovery of PAM-cys peptides from bovine serum albumin (BSA) was 88.6% at 10 picomol in one-dimensional (1-D) SDS-PAGE and 97.1% at 50 picomol in two-dimensional (2-D) SDS-PAGE. The coverage of tryptic peptide of BSA in 1-D and 2-D SDS-PAGE was 83.7% and 81.1%, respectively. The advantages of in situ alkylation with acrylamide were the following: (i) cysteinyl peptides were effectively derived in a single PAM cys and then proteins were precisely identified using databases; (ii) marked reduction of salts compared with post alkylation, e.g., using carboxymethylamide (CAM), resulting in higher signal intensity and wider coverage of cysteinyl peptides from PAM cys, compared with those of CAM derivatives, in mass spectrometry peptide mapping; and (iii) shorter duration by excluding the processes of post alkylation and desalting before peptide mapping.

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PubMed1991

Acrylamide neuropathy in a South African factory: an epidemiologic investigation.

Acrylamide monomer concentrations and peripheral neurotoxicity were investigated in workers at a factory producing polymer. Monomer levels ranged from 0.07 to 2.5 times the recommended exposure limit of the U.S. National Institute for Occupational Safety and Health (1988). Those workers with exposure exceeding the limit had increased prevalences of acrylamide-related abnormalities. Logistic regression showed dose-response relationships with exposure for symptoms, abnormal sensation, decreased motor strength, abnormal gait or rombergism, and skin abnormalities. The overall prevalence of acrylamide-related abnormality was 32% in the total work force and 67% among those exceeding the limit compared with 14% in those exposed below the limit. Environmental exposure determinations and conventional clinical approaches are relatively insensitive measures. Associations might have been stronger if a biological exposure measure had existed and if quantitative neurometric techniques had been applied. Electrophysiological methods are not readily available in many settings; the use of the Vibration II for quantitative field testing holds promise.

Acrylamides↗

PubMed1996

Comparison of behavior of N-substituted acrylamides and celluloses on double-stranded DNA separations by capillary electrophoresis at 25 degrees and 60 degrees C.

The behavior of N-substituted poly(acrylamides) and of cellulose in the separation of double-stranded DNA by capillary zone electrophoresis (CZE) is evaluated. Contrary to previously held belief, which attributed best separations in poly(acrylamides) to small DNA fragments (typically in the 50-1000 bp size range) and in celluloses to large DNA fragments, we show that also celluloses can achieve fine sieving of short DNA sizes provided they are used at much higher concentrations than previously reported. For example, in the case of hydroxyethylcellulose (HEC), typically used at 0.2-0.8% concentrations, levels of 3% produce excellent patterns, at 25 degrees C, in the 50-600 bp size range. If separations are conducted at 60 degrees C, sieving is lost in most liquid polymers. However, if the concentration of HEC is raised to 6% and that of hydroxypropylmethylcellulose (HPMC) above 1%, sieving is fully restored. Also, N-substituted acrylamido derivatives, notably N-acryloylaminoethoxyethanol (AAEE) and N-acryloylaminopropanol (AAP) offer excellent performance at both 25 degrees and 60 degrees C, whereas plain poly(acrylamide) irreversibly collapses at high temperatures, possibly due to intrinsic instability of the amido bond under such harsh conditions. Among all the polymers investigated, an 8% solution of poly(AAP) offers the best performance and highest theoretical plates in the 25 degree-60 degree C interval. Separations at high temperatures are necessary when dealing with detection of point mutations in temperature-programmed CZE and are preferred in DNA sequencing. Two additional advantages are evident when running DNA separations at 60 degrees C: a marked reduction of analysis times and a linearization of the transit times of the larger (434-587 bp) DNA fragments, in all polymers tested.

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PubMed2004

Microemulsion electrokinetic chromatography for the analysis of acrylamide in food.

The influence of microemulsion electrokinetic chromatography (MEEKC) operating conditions, such as the type of water-immiscible alcohol, aqueous phosphate buffer concentration, pH, as well as the addition of methanol and 2-propanol, on acrylamide migration has been studied. These parameters have been optimized taking into account the presence of matrix signals, in order to avoid the interference of these peaks in acrylamide determination. The best separations were achieved using a microemulsion consisting of 0.8% m/v n-amyl alcohol, 3.3% m/v sodium dodecyl sulfate (SDS), 6.6% m/v 1-butanol, and 89.3% m/v 40 mM phosphate buffer at pH 6.5 working at 15 kV in uncoated silica capillaries. Linear calibration curves over the range studied (1.25-125 microg x mL(-1)), the detection limit (0.70 microg x mL(-1)), and both run-to-run (up to 3.4% for concentration and 1.6% for time values) and day-to-day precision (lower than 11.6% for concentration) have been established. Finally, the applicability of the MEEKC method developed has been demonstrated by analyzing levels of acrylamide present in samples of home-made French fries.

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PubMed1981

Acrylamide neurotoxicity in the mouse: a behavioral, electrophysiological and morphological study.

The development of acrylamide induced neurotoxicity was followed for 3 weeks in the mouse by behavioral testing, determination of conduction velocities and electron microscopic examination of peripheral nerves. Neurotoxic signs began to appear during the second week of treatment. A condition of severe intoxication developed within 21 days. Behavioral assessment for neurological deficits proved to be more sensitive than sensory or motor conduction velocity determinations either in isolated preparations or in situ. In general, such electrophysiological determinations did not result in reproducible, statistically significant, differences from control animals until the third week of acrylamide administration. However, there was a suggestion that temperature reduction may provide a provocative change to increase the sensitivity of such electrophysiological measurements. Electron microscopic examination of the nerves of severely poisoned animals revealed myelin corrugation and delamination to be the most consistent damage. Acrylamide appeared to produce a nonselective attack since degenerating fibers were found intermingled with almost normal fibers of approximately the same diameter. In general, the production of neurotoxicity in the mouse closely resembled that seen in the rat but some differences were noted.

Acrylamides↗

PubMed2000

Acrylamide quenching of apo- and holo-alpha-lactalbumin in guanidine hydrochloride.

We have examined the fluorescence properties and acrylamide quenching of calcium-loaded (holo) and calcium-depleted (apo) alpha-lactalbumin (alpha-LA) as a function of guanidine hydrochloride (GDN/HCl) concentration. The spectral changes accompanying increasing GDN/HCl are consistent with protein unfolding and a release of internal fluorescence quenching, which occurs among the three tryptophan residues located in the region of the so-called "tertiary fold." Values for the intrinsic fluorescence emission, the wavelength maximum of the emission, the Stern/Volmer dynamic quench constant, and the static quench constant are consistent with a significant stabilization effect by calcium against protein unfolding. The dynamic quench constant of apo-alpha-LA increases fourfold to its maximum, in the transition from the native state to protein in 1.5 M GDN/HCl. The dynamic quench constant for holo-alpha-LA remains unchanged until exposed to 2.5 M GDN/HCl, but increases by threefold with addition denaturant to 4 M GDN/HCl. The static quench constant of the apo-protein in the native solvent, approximately 0.2 M(-1), declines to zero in 1 M denaturant, where the molten globule folding intermediate is most populated. A more protracted denaturant-dependent decline in the static quench constant occurs for the holo-protein. Sharp increase in the static quenching occurs for apo-alpha-LA and holo-alpha-LA above 1.5 M GDN/HCl and 3.5 M GDN/HCl, respectively. The results for apo-alpha-LA in dilute GDN/HCl suggest that acrylamide can penetrate the protein molecule (as judged by the collision quenching) but is unable to form a stable complex within the quenching domain for the tryptophans (as judged by the absence of the static quench constant). It seems reasonable to suggest that the protein folding intermediate which occurs in dilute denaturant represents a structure in which the tryptophans are, on average, more accessible to collisional quenching but sufficiently compact to prevent formation of a stable, dark equilibrium complex with acrylamide.

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PubMed2005

In vitro studies of the influence of certain enzymes on the detoxification of acrylamide and glycidamide in blood.

Several enzymes involved in the metabolism of xenobiotic substances are polymorphic in humans. Inter-individual differences in response to certain chemicals, such as acrylamide, as a result of such genetic polymorphisms might affect health-risk assessments. Detoxification by, for example, conjugation with glutathione (GSH) will decrease the concentration. The dose of the compound and enzymes that enhance the conjugation with GSH will increase the detoxification rate. The dose of acrylamide or glycidamide has been measured in blood samples from individuals with defined genotypes for the glutathione transferases GSTT1 and GSTM1 after in vitro incubation with these compounds. The results indicate that these enzymes have no significant effect on the blood dose, measured as Hb adducts over time, after exposure to acrylamide or glycidamide.

Acrylamide↗

PubMed2005

Determination of acrylamide in various food matrices: evaluation of LC and GC mass spectrometric methods.

Recent concerns surrounding the presence of acrylamide in many types of thermally processed food have brought about the need for the development of analytical methods suitable for determination of acrylamide in diverse matrices with the goals of improving overall confidence in analytical results and better understanding of method capabilities. Consequently, the results are presented of acrylamide testing in commercially available food products--potato fries, potato chips, crispbread, instant coffee, coffee beans, cocoa, chocolate and peanut butter, obtained by using the same sample extract. The results obtained by using LC-MS/MS, GC/MS (El), GC/HRMS (El)--with or without derivatization--and the use of different analytical columns, are discussed and compared with respect to matrix borne interferences, detection limits and method complexities.

Acrylamide↗

PubMed2005

Model systems for evaluating factors affecting acrylamide formation in deep fried foods.

Simulated food pieces constructed from fiberglass pads (models for French fries and chips) were used as carriers for defined aqueous solutions, dispersions of test substances and ingredients to evaluate acrylamide formation. The pads were loaded with a solution containing asparagine and glucose (10 mM each) plus selected reaction modulators before deep fat frying and analysis for acrylamide. Data from fiberglass models along with companion sliced potato samples were used in developing hypotheses for the mechanisms involved in the suppression of acrylamide formation by polyvalent cations, polyanionic compounds, pH, and altered food polymer states in fried potato products.

Acrylamide↗

PubMed1981

Enhancement of sensitivity to acrylamide after nerve ligature.

Acrylamide given to rats after damage to the posterior tibial nerve by a tight ligature causes retrograde degeneration of axons. The number of fibres affected and the extent of degeneration towards the cell body are dose dependent. The effect is the same whether the acrylamide is given immediately after ligature or one week later. The degeneration is delayed several days after giving acrylamide. Before axonal disintegration occurs, focal accumulations of SER, vesicle and multivesicular bodies are seen beneath the axon membrane. Associated with these changes larger vacuoles occur, either in the axon or external to it. It is suggested that these early changes are a response by the axon and perikaryon to the local metabolic damage caused by the toxic chemical. Somewhat similar changes also occur in early predegenerative INH intoxication, and before the axon degeneration in O-P neurotoxicity.

Acrylamides↗

PubMed1981

'Acrylamide-induced' neuropathy and impairment of axonal transport of proteins. II. Abnormal accumulations of smooth endoplasmic reticulum as sites of focal retention of fast transported proteins. Electron microscope radioautographic study.

The distribution of fast axonally transported proteins was studied by electron microscope radioautography in ciliary ganglia of chickens treated or not treated with acrylamide. At 3 h after the intracerebral injection of [3H]lysine, the preganglionic axons of the untreated chickens displayed few silver grains, mainly associated with smooth endoplasmic reticulum (SER) profiles. In most axons of acrylamide-treated chickens, a similar pattern was observed, except in axons which exhibited focal and intense labeling underneath the axolemma: clusters of silver grains indeed overlayed peripheral accumulations of tubulovesicular profiles of SER, dense core vesicles and mitochondria. After impregnation with heavy metals, electron microscope observation of 1 micrometer thick sections showed a locally disorganized SER forming a complex network of tubules intermingled with vesicles and mitochondria. Such a local disorganization of the peripheral SER in the distal part of the axons, could be responsible for the focal stasis of fast transported proteins; it seems to be one of the earliest changes detectable in axons damaged by acrylamide treatment.

Acrylamides↗

PubMed1987

Properties of acrylamide gels cross-linked with low concentrations of N,N'-diallyltartardiamide.

The behavior of proteins on acrylamide gels cross-linked with low concentrations of N,N'-diallyltartardiamide (DATD) has been studied from a theoretical and practical point of view. Modifications in methodology and a technique for calculation of apparent molecular weights (MWs) allowed accurate determinations on gels from 7 up to 15% acrylamide. Comparison of viral protein patterns obtained with DATD- or N,N'-methylenebisacrylamide-cross-linked gels indicated greater resolution by DATD gels, particularly in the higher MW range. The polymerization reaction was studied kinetically and found to be efficient so long as the ratio of DATD to acrylamide was low. High resolution of DATD gels was attributed to the spontaneous formation of a gradient over much of the gel that retarded diffusion of the protein bands.

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PubMed1980

Effect of diethyl maleate on acrylamide induced neuropathy in rats.

Pre-administration of diethyl maleate (DEM) to rats resulted in an earlier onset and development of hind limb paralysis following acrylamide administration than in rats treated with acrylamide only. A marked depletion of brain biogenic amine content and of glutathione levels was also observed in the DEM pretreated groups. Depletion of cellular glutathione would appear to lead to an increased neurotoxicity of acrylamide.

Acrylamides↗

PubMed1981

Effects of acrylamide given during gestation on dopamine receptor binding in rat pups.

Acrylamide (20 mg/kg) was administered by gavage to time-pregnant Fischer 344 rats daily from day 7 to day 16 of gestation. Acrylamide did not affect the number, size, or body weights of litters obtained but did decrease the [3H]spiroperidol binding in striatal membranes of 2-week-old pups. This effect could not be seen at 3 weeks of age. Scatchard analysis showed that acrylamide changed the affinity as well as the number of dopamine receptor sites. There were no signs of maternal toxicity in dosed mothers as evaluated by their body weights or general appearance.

Acrylamides↗

PubMed1985

Effect of acrylamide and related compounds on glycolytic enzymes of rat brain.

The in vitro effect of acrylamide and its analogues on rat brain glycolytic enzymes was examined to elucidate the biochemical lesions responsible for the pathogenesis of acrylamide-induced neuropathy. All test compounds inhibited glyceraldehyde-3-phosphate dehydrogenase, irrespective of their neurotoxicity, and their inhibitory potency was a linear function of the rate constant with reduced glutathione. Phosphofructokinase was also inhibited by some of the test compounds, independently of their neurotoxicity. The rate-limiting enzymes in glycolysis, hexokinase and pyruvate kinase, were not inhibited by acrylamide.

Acrylamides↗

PubMed2005

Development of a quantitative method for determination of acrylamide in infant powdered milk and baby foods in jars using isotope dilution liquid chromatography/electrospray ionization tandem mass spectrometry.

An improved method has been developed for the determination of acrylamide in infant powdered milk and baby foods in jars, a particular class of foodstuffs which represent an important source of nutrition for young infants and babies. This method uses isotope dilution liquid chromatography coupled to a tandem mass spectrometer with electrospray ionization and is significantly more sensitive than previous published methods with a limit of quantification estimated at 1 microg kg(-1). The new method offers effective sample preparation procedures including defatting with petroleum ether, extraction with aqueous solution of sodium chloride, further liquid-liquid extraction with ethyl acetate and clean-up by solid-phase extraction (SPE) with HLB 200 mg cartridges. The analytical method was well validated and good results were obtained with respect to repeatability (RSD < 5%) and recovery (86-97%) which fulfilled the requirements defined by European Union (EU) legislation. The acrylamide level in infant powdered milk and baby foods in jars were 3.01-9.06 microg kg(-1) and 6.80-124.93 microg kg(-1), respectively. Especially, this new method is successfully applied to the trace quantification of acrylamide in infant/baby foods, the content of which is less than 10 microg kg(-1).

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