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PubMed1989

Assessment of the role of tryptophan residues in phospholipase A2 by fluorescence quenching.

Tryptophan (Trp) fluorescence of two phospholipases A2 (PLA2) from Naja naja atra and Naja nigricollis snake venoms was quenched by acrylamide and iodide. Trp residues in N. naja atra PLA2 were equally accessible to acrylamide and iodide. Iodide quenching studies indicate that there are two classes of Trp fluorophores in N. nigricollis CMS-9. The accessible class consists of Trp-18 and Trp-19. Removal of the N-terminal octapeptide caused a perturbation of the micro-environment of the Trp residues in the PLA2 enzymes. The presence of a substrate lowers the susceptibility of the Trp residues to iodide quenching in N. naja atra PLA2, suggesting that all three Trp residues are at the substrate binding site, but in N. nigricollis CMS-9 Trp-18 and Trp-19 are related to substrate binding.

Acrylamide↗
PubMed1990

Methyl vinyl sulphone: a new class of Michael-type genotoxin.

Methyl vinyl sulphone (MVS) is a labile, Michael-reactive chemical, similar in structure to acrylamide (AA). Given that acrylamide is a reference mammalian mutagen and a rodent carcinogen, studies were undertaken to evaluate the potential genotoxicity of MVS. In common with AA, MVS was non-mutagenic to Salmonella but active as an aneugen to cultured mammalian cells. It is concluded that vinyl sulphones should be regarded as representative of a new class of genotoxic chemical whose mode of action is probably primarily dependent upon Michael reactivity to proteins.

Acrylamide↗
PubMed1988

Fluorescence studies on the dissociation and denaturation of pigeon liver malic enzyme.

Exposure of pigeon liver malic enzyme [S)-malate:NADP+ oxidoreductase (oxaloacetate-decarboxylating), EC 1.1.1.40) in medium concentrations of guanidine-HCl at 25 degrees C and pH 7.45 caused biphasic conformational changes of the enzyme molecule. Molecular weight determination confirmed that the enzyme tetramers were dissociated to monomers in phase I transition. Enzymatic activity was completely lost in this phase. Recovery of the enzyme activity was only possible in the early stages of the phase I transition. Phase II was due to enzyme unfolding, as judged by circular dichroism and the fluorescence parameters of the enzyme. The steps of the transformation of native malic enzyme into a completely denatured state were in the following sequence: tetramer----monomer----random coil. Extensive denaturation of the enzyme molecule resulted in irreversible aggregation. Dissociation and denaturation were accompanied by a red-shift of the fluorescence spectrum (328----368 nm). Fluorescence quenching studies indicated that tryptophan residues of the enzyme molecule were buried deeply in the interior of the molecule. The tryptophan residues were only partially accessible by acrylamide and almost inaccessible by KI. Dissociation and denaturation were accompanied by exposure of the tryptophan residues, as manifested by the accessibility of the enzyme molecule toward KI or acrylamide.

Acrylamide↗
PubMed1988

Fluorescence quenching studies of bovine growth hormone in several conformational states.

The use of steady-state fluorescence quenching methods is reported as a probe of the accessibility of the single fluorescent tryptophan residue of bovine growth hormone (bGH, bovine somatotropin, bSt) in four solution-state conformations. Different bGH conformations were prepared by using previous knowledge of the multi-state nature of the equilibrium unfolding pathway for bGH: alterations in denaturant and protein concentration yielded different bGH conformations (native, monomeric intermediate, associated intermediate and unfolded). Because the intramolecular fluorescence quenching which occurs in the native state is reduced when the protein unfolds to any of the other conformations, steady-state fluorescence intensity measurements can be used to monitor bGH unfolding as well as the formation of the associated intermediate. These steady-state intensity changes have been confirmed with fluorescence lifetime measurements for the different conformational states of bGH. Fluorescence quenching results were obtained using the quenchers iodide (ionic), acrylamide (polar) and trichloroethanol (non-polar). Analysis of the results for native-state bGH reveals that the tryptophan environment is slightly non-polar (in agreement with the emission maximum of 335 nm) and the tryptophan is more exposed to acrylamide than most native-state tryptophan residues which have been studied. The tryptophan is most accessible to all quenchers in the unfolded state, because no steric restrictions inhibit quencher interaction with the tryptophan residue. The iodide quenching results indicate that the associated intermediate tryptophan is not accessible to iodide, probably due to negative charges inhibiting iodide penetration. The associated intermediate tryptophan is less accessible to all three quenchers than the monomeric intermediate tryptophan, due to tight packing of molecules in the associated intermediate state.

Acrylamide↗
PubMed1986

Viscosity dependence of the solute quenching of the tryptophanyl fluorescence of proteins.

We have studied the viscosity dependence of the acrylamide quenching of the fluorescence on the internal tryptophan residues in cod parvalbumin and ribonuclease T1, as well as the model systems. N-acetyl-L-tryptophanamide and glucagon. For the latter systems, the apparent rate constant, kq(app), for acrylamide quenching shows a typical diffusion-limited behavior. For parvalbumin and ribonuclease T1, however, the viscosity dependence of kq(app) is quite different. There is little change in the kq(app) values on increasing the bulk viscosity from 1 to 10 cP (by addition of glycerol), but a further increase from 10 to 100 cP results in a significant reduction in the kq(app). Both an unfolding mechanism and a quencher penetration mechanism are considered to explain the results. Only the penetration mechanism is found to be consistent, and our data are interpreted as indicating that the rate-limiting step for quenching goes from being that of diffusion through the protein matrix, at low viscosity, to diffusion through the bulk solvent, at high viscosity. By also considering the Kramers' relationship in fitting our data, we are able to obtain insight regarding the coupling between internal fluctuations in the structure of the protein and motion of the bulk solvent. For parvalbumin and ribonuclease T1, the internal dynamics are found to be very weakly coupled to the bulk.

Acrylamide↗
PubMed1993

Tryptophan fluorescence quenching in rabbit skeletal myosin rod.

The solvent accessibility of the four tryptophans of rabbit skeletal muscle myosin rod was investigated using steady-state and time-resolved fluorescence quenching by iodide, acrylamide, and cesium. The quenching by iodide and acrylamide was biphasic; the discrete, long lifetime component was quenched with bimolecular collision constants (kq) of 1 x 10(9) M-1 s-1 and 1.6 x 10(9) M-1 s-1, respectively, while the Gaussian distributed, short lifetime component was quenched with a kq value of 0.3 x 10(9) M-1 s-1 and 0.04 x 10(9) M-1 s-1, respectively. Comparison with kq values for N-acetyl-tryptophanamide indicated that the fractional solvent accessibility was about 25% for the long and less than 10% for the short lifetime component. Cesium quenching was monophasic and provided evidence of an excess of positive charge around these tryptophans. Our findings cast doubt on the general application of the simple coiled-coil model to describe coiled-coil interactions in this protein in solution.

Acrylamide↗
PubMed1996

Use of fluorescence decay times of 8-ANS-protein complexes to study the conformational transitions in proteins which unfold through the molten globule state.

The conformational transitions starting with the native protein, passing the molten globule state and finally approaching the unfolded state of proteins was investigated for bovine carbonic anhydrase B (BCAB) and human alpha-lactalbumin (alpha-HLA) by means of fluorescence decay time measurements of the dye 8-anilinonaphthalene-1-sulphonic acid (8-ANS). Stepwise denaturation was realized by using the denaturant guanidinium chloride (GdmCl). It was shown that 8-ANS bound with protein yields a double-exponential fluorescence decay, where both decay times considerably exceed the decay time of free 8-ANS in water. This finding reflects the hydrophobic environment of the dye molecules attached to the proteins. The fluorescence lifetime of the short-time component is affected by protein association and can be effectively quenched by acrylamide, indicating that 8-ANS molecules preferentially bind at the protein surface. The fluorescence lifetime of the long-time component is independent of the protein and acrylamide concentration and may be related to protein-embedded dye molecules. Changes of the long lifetime component upon GdmCl-induced denaturation and unfolding of BCAB and alpha-HLA correlate well with overall changes of the protein conformation. The transition from native protein to the molten globule state is accompanied by an increase of the number of protein-embedded 8-ANS molecules, while the number of dye molecules located at the protein surface decreases. For the transition from the molten globule to the unfolded state was the opposite behaviour observed.

Acrylamide↗
PubMed1993

Protective effects of SR 57746A in central and peripheral models of neurodegenerative disorders in rodents and primates.

Compounds possessing neurotrophic properties may represent a possible treatment for neurodegenerative disorders such as Alzheimer's disease. SR 57746A, 1-[2-(naphth-2-yl)ethyl]-4-(3-trifluoromethylphenyl)-1,2,5,6- tetrahydropyridine hydrochloride, is a new compound with neurotrophic activity in a number of in vitro preparations. The neurotrophic effects of this compound have been evaluated in vivo using four distinct rat models of neurodegeneration: transient global ischaemia produced by a four-vessel occlusion; septohippocampal lesion produced by injection of vincristine sulphate into the medial septum; sciatic nerve crushing; and acrylamide-induced peripheral neuropathy. Rats were administered vehicle or 2.5-10 mg/kg p.o. SR 57746A, after initiation of the degenerative process, then once daily for 10 days in the first two models, 16 days in the third and 26 days in the fourth model. Median scores for ischaemia-induced neuronal damage were reduced by 30-40% by SR 57746A treatment in hippocampal CA1, CA2, and CA3 regions, and in the dorsal striatum. Twelve days after intraseptal vincristine administration, there was a marked loss of septohippocampal cholinergic neurons, as indicated by reduced choline acetyltransferase activity in both the septum and hippocampus. SR 57746A dose-dependently reversed this reduction in both areas. These results were confirmed by histoenzymological evaluation of hippocampal acetylcholinesterase content. SR 57746A also reversed the loss of hippocampal choline acetyltransferase induced by intraseptal vincristine in marmosets. Behavioral deficits in these models (exploratory behaviour in the former and short-term social memory in the latter) were also significantly reduced by SR 57746A treatment. In the sciatic crush model, sensorimotor function improved more rapidly in rats treated with 10 mg/kg SR 57746A. In this same model, SR 57746A (10 mg/kg/day) also significantly increased the length of regenerated nerve eight days after the crush, as measured using the pinch test. Finally, SR 57746A retarded the onset, reduced the amplitude and accelerated the recovery of acrylamide-induced peripheral neuropathy. Thus, SR 57746A possesses notable neurotrophic activity in a variety of neurodegenerative models in vivo, suggesting that the compound may possess therapeutic potential for the treatment of neurodegenerative diseases.

Acetylcholinesterase↗
PubMed1993

The effect of organophosphates on a chicken brain or sea urchin egg kinesin-driven microtubule motility assay.

The effect of neuropathic and non-neuropathic organophosphates (OPs) and acrylamide on an in vitro kinesin-driven microtubule (MT) motility assay was compared. The goal of the study was to determine whether this in vitro assay could confirm that a mechanism of action of neuropathic OPs was to impair kinesin activity and, therefore, possibly fast axonal anterograde transport (FAAT) in vivo. For our study, kinesin from chicken brain (CK) and sea urchin egg (SUK) was initially purified. Western immunoblotting confirmed the close antigenic homology between CK and SUK, using a mouse monoclonal sea urchin kinesin heavy chain-specific antibody (SUK 4). In the presence of microtubules (MTs) and MgATP, both CK- and SUK-driven MT movement was measured using a video-enhanced differential interference contrast microscope system with computer-assisted analysis. Using this assay system, we then tested separately the effect of two neuropathic OPs (diisopropylfluorophosphate (DFP) and phenyl saligenin phosphate (PSP)) and a non-neuropathic OP (paraoxon (PO)) each at a concentration of 10(-2) M at 27 degrees C. Additionally, we tested acrylamide (10(-2) M), since it is one of the best-characterized neurotoxins impairing FAAT in vivo. Our results demonstrated that none of these compounds significantly affected kinesin-driven MT motility in vitro compared to the standard controls. Further, this assay system was thus not able to discriminate between the neuropathic and non-neuropathic effect of these OPs.

Acrylamide↗
PubMed1996

Characterization of pyridoxal phosphate as an optical label for measuring electrostatic potentials in proteins.

This paper presents data which allow one to characterize pyridoxal 5'-phosphate (PLP) as an optical label for electrostatic potential measurements in proteins. Experimental studies were carried out with 6-N-(5'-phosphopyridoxyl)-2-N-acetyl-lysyl methyl ester (PLP-ALME) as a model compound which simulates PLP covalently bound to a protein. Calculations of electrostatic potential maps were done using the model compound 2,4-dimethyl-3-hydroxy-5-hydroxymethyl phosphate-pyridine (DHHPP). Studies on relative changes in PLP-ALME fluorescence and absorbance vs. pH resulted in four pKa values of PLP-ALME in solution which can be used as intrinsic pKa values (pKint) of the ionizable groups of the label covalently bound to the protein. The pKa values obtained from fluorescence data are 4.1, 5.6, 8.7 and 11.1 and those from absorbance data are 3.1, 4.7, 8.7 and 11.0. The differences between corresponding pKa values are related to differences in PLP-ALME behaviour between the excited and ground electronic states and to intramolecular charge-charge interactions. Quenching of PLP-ALME fluorescence by I-, acrylamide and Cs+ at pH 6, 7 and 8 shows that in the case of I- and acrylamide the Stern-Volmer constants of quenching (Ksv) decrease with increasing pH, while the opposite is true for Ksv of Cs+. These results as well as the analysis of electrostatic potential maps of DHHPP show that with its ampholytic character PLP can be used to measure local electrostatic potentials in the pH range 5-9.

Acrylamide↗
PubMed1993

Electrophoresis of DNA in ultrathin planar-format linear polyacrylamide.

Linear or un-cross-linked polyacrylamides have been employed successfully in the field of capillary electrophoresis for the separation of nucleic acids. Typical acrylamide concentrations for those applications range from 3% to 14% (wt/vol), with consistencies ranging from virtually liquid to moderately viscous. Due to the absence of cross-links, and the relatively fluid nature of linear polyacrylamide at typically employed concentrations, its use in planar (slab) gel electrophoresis has been overlooked. We describe herein the application of ultrathin (100 microns) high-viscosity slabs of linear polyacrylamide to planar electrophoresis of nucleic acid fragments. The approach we describe is rapid and yields high-resolution separations of nucleic acid fragments in linear polyacrylamide supports. The mobilities of DNA fragments of various lengths in a range of concentrations of linear polymer are compared with those observed for conventional cross-linked gels. The reptative migration of larger DNA fragments in linear polymers is predictable from the models derived from work with cross-linked acrylamide and agarose. The migration of smaller fragments, however, is not entirely predicted by the Ogston model. The relative mobilities observed for very small DNA fragments are approximately half those predicted by the Ogston regimen.

Acrylamide↗
PubMed1987

Frequency domain measurements of the fluorescence lifetime of ribonuclease T1.

Using multifrequency phase/modulation fluorometry, we have studied the fluorescence decay of the single tryptophan residue of ribonuclease T1 (RNase T1). At neutral pH (7.4) we find that the decay is a double exponential (tau 1 = 3.74 ns, tau 2 = 1.06 ns, f1 = 0.945), in agreement with results from pulsed fluorometry. At pH 5.5 the decay is well described by a single decay time (tau = 3.8 ns). Alternatively, we have fitted the frequency domain data by a distribution of lifetimes. Temperature dependence studies were performed. If analyzed via a double exponential model, the activation energy for the inverse of the short lifetime component (at pH 7.4) is found to be 3.6 kcal/mol, as compared with a value of 1.0 kcal/mol for the activation energy of the inverse of the long lifetime component. If analyzed via the distribution model, the width of the distribution is found to increase at higher temperature. We have also repeated, using lifetime measurements, the temperature dependence of the acrylamide quenching of the fluorescence of RNase T1 at pH 5.5. We find an activation energy of 8 kcal/mol for acrylamide quenching, in agreement with our earlier report.

Acrylamide↗
PubMed1998

Spectroscopic properties and stability of the neurotoxic complex. Vipoxin and its components.

The neurotoxin Vipoxin from the venom of Vipera ammodytes meridionalis is a complex between a toxic basic phospholipase A2 (PLA2) and a non-toxic acidic protein inhibitor (Inh). Tryptophan fluorescence parameters are determined for the complex and for its components. Iodide, caesium and acrylamide are not efficient quenchers of the Vipoxin indole emission. Increased accessibilities of tryptophans to ionic and neutral quenchers are found after the dissociation of the complex. Trp 20 and Trp 31 became more 'exposed' in the separated individuals proteins. The indole rings of the complex are located in a positively charged environment. Inspection of the Vipoxin X-ray model showed that the three tryptophyl side chains are located in the interface region between the enzyme and the inhibitor and are completely 'exposed' in the separated components of the complex. In Vipoxin an efficient 'interchain' energy transfer between tyrosyl and tryptophyl residues from different polypeptide chains occurs. Static quenching with acrylamide is also detected in PLA2 and Inh. The free energy changes deltaG D for the unfolding reactions of Vipoxin, PLA2 and Inh are determined in circular dichroism spectroscopy. The complex formation between the toxic PLA2 and the inhibitor increases deltaG HD2O to 23.5 kJ mol-1.

Acrylamide↗
PubMed1993

Quenching of intrinsic fluorescence of yeast cytochrome c peroxidase by covalently- and noncovalently-bound quenchers.

The intrinsic steady-state fluorescence of the heme enzyme cytochrome c peroxidase (CCP) has been characterized as a probe of its structure in solution. The fluorescence is dominated by tryptophan emission, which has a quantum yield of 7% relative to the tryptophan standard N-acetyltryptophanamide, and an emission maximum at 324 nm indicative of a relatively hydrophobic environment for the fluorescent residues. These fluorescence properties are consistent with the known structure of CCP; six of the seven tryptophan residues are well within quenching distance for efficient Förster energy transfer to the heme, so that the intrinsic fluorescence arises largely from Trp101 which is approximately 26 A from the heme and partially buried. Quenching studies using Cs+, I-, and acrylamide are also consistent with this picture, since the charged species are poor quenchers, but acrylamide, which can penetrate the protein matrix, is a more effective quencher. The intrinsic fluorescence of two CCP derivatives with the quencher pentaammineruthenium(III) covalently attached to His6 and His60 has also been characterized. The His60 derivative, shown by X-ray analysis to be essentially structurally identical to native CCP, is 17% less fluorescent than native CCP, consistent with the quenching expected from distance calculations and the assignment of Trp101 as the major fluorescent center. The observed quenching of 38% in the second derivative is close to that predicted for ruthenation of His6 assuming that Trp101 is the major fluorophore. The fluorescence of compound I of CCP is also reported. This species, which has a ferryl (FeIV = O) heme and a protein radical purportedly on Trp191, exhibits 9% higher fluorescence than native CCP.(ABSTRACT TRUNCATED AT 250 WORDS)

Acrylamide↗
PubMed1994

Factors affecting the stability and conformation of Locusta migratoria apolipophorin III.

Apolipophorin III (apoLp-III) from the migratory locust, Locusta migratoria, represents the only full-length apolipoprotein whose three-dimensional structure has been solved. In the present study, spectroscopic methods have been employed to investigate the effects of deglycosylation (via endoglycosidase F treatment) and complexation with lipid on the stability and conformation of this protein. Addition of isolated lipid-free apoLp-III to sonicated vesicles of dimyristoylphosphatidylcholine (DMPC) resulted in the formation of relatively uniform disklike complexes with an average Strokes diameter of 13.5 nm. Flotation equilibrium experiments conducted in the analytical ultracentrifuge revealed a particle molecular mass of 588 500 Da. Chemical cross-linking and compositional analysis of apoLp-III.DMPC complexes indicated five apoLp-III molecules per disk and an overall DMPC:apoLp-III molar ratio of 122:1. Circular dichroism (CD) spectra of apoLp-III samples suggested a loss of alpha-helical structure upon deglycosylation, while complexation with DMPC did not significantly alter the helix content (estimated to be > 75%). Fluorescence spectroscopy revealed that the apoLp-III tryptophan fluorescence emission maximum was blue-shifted from 347 to 332 and 321 nm upon deglycosylation and complexation with DMPC, respectively. In quenching experiments with native apoLp-III, tryptophan residues were shielded from the positively charged quencher, CsCl. Increased exposure to KI, CsCl, and acrylamide was observed upon deglycosylation, whereas complexation with DMPC yielded lower Ksv values for KI and acrylamide and an increased value for CsCl versus native lipid-free apoLp-III. In guanidine hydrochloride denaturation studies monitored by CD or fluorescence, native, lipid-free apoLp-III displayed a denaturation midpoint of 0.60 M, and delta GDH2O = 5.37 kcal/mol was calculated.(ABSTRACT TRUNCATED AT 250 WORDS)

Acrylamide↗
PubMed1991

Intrinsic tryptophan fluorescence of Schizosaccharomyces pombe mitochondrial F1-ATPase. A powerful probe for phosphate and nucleotide interactions.

Mitochondrial F1 from the yeast Schizosaccharomyces pombe, in contrast to the mammalian enzyme, exhibits a characteristic intrinsic tryptophan fluorescence with a maximal excitation at 291 nm and a maximal emission at 332 nm. Low values of Stern-Volmer quenching constants, 4.0 M-1 or 1.8 M-1, respectively, in the presence of either acrylamide or iodide, indicate that tryptophans are mainly buried inside the native enzyme. Upon subunit dissociation and unfolding by 6 M guanidine hydrochloride (Gdn.HCl), the maximal emission is shifted to 354 nm, a value very similar to that obtained with N-acetyltryptophanamide, a solute-tryptophan model compound. The tryptophan content of each isolated subunit has been estimated by fluorescence titration in the presence of Gdn.HCl with free tryptophan as a standard. Two tryptophans and one tryptophan are found respectively in the alpha and epsilon subunits, whereas none is detected in the beta, gamma, and delta subunits. These subunit contents are consistent with the total of seven tryptophans estimated for native F1 with alpha 3 beta 3 gamma 1 delta 1 epsilon 1 stoichiometry. The maximal emission of the isolated epsilon subunit is markedly blue-shifted to 310-312 nm by interaction with the isolated delta subunit, which suggests that the epsilon subunit tryptophan might be a very minor contributor to the native F1 fluorescence measured at 332 nm. This fluorescence is very sensitive to phosphate, which produces a marked blue shift indicative of tryptophans in a more hydrophobic environment. On the other hand, ADP and ATP quench the maximal emission at 332 nm, lower tryptophan accessibility to acrylamide, and reveal tryptophan heterogeneity.

Acrylamide↗
PubMed1986

Fluorescence studies on a membrane-embedded peptide from the carboxy terminus of lipophilin.

Fluorescence of an intramembranous polypeptide (T-3) derived from the carboxy-terminal sequence of lipophilin was studied in aqueous solution, detergent micelles, and lipid vesicles. In all cases, the fluorescence of the only Trp (211) was indicative of a hydrophobic, buried residue. Addition of lysophosphatidylcholine (LPC) or phosphatidylcholine (PC) gave Trp-211 a more hydrophobic, less quenching environment as compared to that in aqueous solution. Energy transfer between Trp and Tyr observed in aqueous solution was decreased by the addition of lipid or detergent. There was limited quenching by acrylamide both in the aqueous and in the lipid or detergent environments. However, PC or LPC further decreased this quenching. Cs+ and I- were even less accessible than acrylamide to Trp, further proving that the Trp was located inside the lipid bilayer. The quenching indicated that I- binds to positive charges of the protein located on the surface of the membrane. This, combined with knowledge of the sequence of lipophilin, suggested that Trp-211 was located within the membrane but was close to amino acid residues that are external to the bilayer.

Acrylamide↗
PubMed1989

Time-resolved fluorescence spectroscopy of human adenosine deaminase: effects of enzyme inhibitors on protein conformation.

Adenosine deaminase, a purine salvage enzyme essential for immune competence, was studied by time-resolved fluorescence spectroscopy. The heterogeneous emission from this four-tryptophan protein was separated into three lifetime components: tau 1 = 1 ns and tau 2 = 2.2 ns an emission maximum at about 330 nm and tau 3 = 6.3 ns with emission maximum at about 340 nm. Solvent accessibility of the tryptophan emission was probed with polar and nonpolar fluorescence quenchers. Acrylamide, iodide, and trichloroethanol quenched emission from all three components. Acrylamide quenching caused a blue shift in the decay-associated spectrum of component 3. The ground-state analogue enzyme inhibitor purine riboside quenched emission associated with component 2 whereas the transition-state analogue inhibitor deoxycoformycin quenched emission from both components 2 and 3. The quenching due to inhibitor binding had no effect on the lifetimes or emission maxima of the decay-associated spectra. These observations can be explained by a simple model of four tryptophan environments. Quenching studies of the enzyme-inhibitor complexes indicate that adenosine deaminase undergoes different protein conformation changes upon binding of ground- and transition-state analogue inhibitors. The results are consistent with localized structural alterations in the enzyme.

Acrylamide↗

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