Effect of herbicide tralkoxydim and 2-acylcyclohexane-1,3-diones on peroxidase activity

Effect of 2-acylcyclohexane-1,3-dione derivatives (tralkoxydim and its diketone precursors) on peroxidase-catalyzed oxidation of 3,3',5,5'-tetramethylbenzidine (TMB), o-phenylenediamine (PDA), and the phenol-4-aminoantipyrine (4-AAP) couple has been studied. This effect varies from horseradish peroxidase (HRP) inactivation to activation in the reactions of peroxidation ofTMB, PDA, and, to a lesser extent, the phenol-4-AAP couple. The diketone-mediated HRP activation depends strongly on pH, presence of dimethylformamide, the structures of tralkoxydim and other diketones, and the substrate nature. The type of activation in the course of peroxidation with the presence of tralkoxydim can be noncompetitive (PDA and TMB) or mixed (TMB) depending on conditions. The maximal level of the HRP activation mediated by diketones depends on their structure. It can reach 4000% of the initial HRP-catalyzed peroxidation rate for TMB and ca. 1000% for PDA. A test system is proposed for quantitative tralkoxydim assay at millimolar concentration. It includes HRP and TMB as the substrate with spectrometrical monitoring of the TMB peroxidation product at 655 nm.     

Cooxidation of phenol and 4-aminoantipyrin, catalyzed by polymers and copolymers of horseradish root peroxidase and Penicillium funiculosum 46.1 glucose oxidase

Polymers and copolymers of horseradish root peroxidase (HRP) and Penicillium funiculosum 46.1 glucose oxidase (GO) have been synthesized and their catalytic properties have been characterized (free and immobilized forms of each enzyme were studied). The cooxidation reaction of phenol and 4-aminoantipyrin (4-AAP), performed in an aqueous medium in the presence of equimolar amounts of GO and HRP, was characterized by effective K _M and k _cat of 0.58 mM and 20.9 s^?1 (for phenol), and 14.6 mM and 18.4 s^?1 (glucose), respectively. The catalytic efficiency of polymerization products (PPs) of GO (GO-PPs) depended on the extent of their aggregation. The combinations GO + HRP-PP and HRP + GO-PP, as well as the copolymer HRP*-GO-PP, proved promising as reagents for enzyme-based analytical systems. When adsorbed on aluminum hydroxide gels, GO-PPs exhibited higher catalytic activity than the non-polymeric enzyme. Maximum retention of GO-PP activity on the inorganic carrier was observed in the case of GO-PP copolymers with an activated HRP. Polymerization of HRP in the presence of a zinc hydroxide gel, paralleled by HRP-PP immobilization onto the gel, increased both the activity of the enzyme and its operational stability.     

The effect of tetrazole and its amino derivatives on the kinetics of peroxidase oxidation of chromogenic substrates

The peroxidase-catalyzed oxidation of 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), o-phenylenediamine (PDA), and 3,3',5,5'-tetramethylbenzidine (TMB) was found to be activated by tetrazole and 5-aminotetrazole (AT) and weakly inhibited by 1,5-diaminotetrazole. The activating action of tetrazole and AT on the PDA and TMB oxidation was clearly discompetitive and that on ABTS was non-competitive. The coefficients (degrees) of activation alpha were determined for three substrates and two activators; they depended on the substrate type and the buffer nature and increased along with the pH growth from 6.4 to 7.2. For AT and tetrazole, the maximal alpha values were 4140 and 800 M(-1), respectively, upon the PDA oxidation and 3570 and 540 M(-1), respectively, upon the TMB oxidation. Lower alpha values (145 and 58 M(-1) for tetrazole and AT, respectively) were characteristic of the peroxidase oxidation of ABTS. The activation of peroxidase oxidation of the substrates by tetrazole and AT at pH > or = 5.4 was explained by the nucleophilic nature of the activators interacting with the amino acid residues in the peroxidase active site according to the mechanism of acid-base catalysis. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2004, vol. 30, no. 3; see also http://www.maik.ru.     

Activation of Peroxidase-Catalyzed Oxidation of Aromatic Amines with 2-Aminothiazole and Melamine

The peroxidase-catalyzed oxidation of 3,3",5,5"-tetramethylbenzidine (TMB), ortho-phenylenediamine (PDA), and 5-aminosalicylic acid (5-ASA) is significantly accelerated in the presence of 2-aminothiazole (AT) and melamine (MA), and an increase in their concentrations is associated with a parallel increase in the k _cat and K _m values for TMB and PDA. The activation of the peroxidase-catalyzed oxidation of TMB and PDA is quantitatively characterized by a coefficient (degree) (M^–1) which significantly depends on pH in the range 6.2-6.4, 6.4-7.4, and 6.0-7.4 for the TMB–AT, TMB–MA, and PDA–MA pairs, respectively. An increase in the coefficient with increase in pH confirms nucleophilicity of activation of the peroxidase-catalyzed oxidation of the aromatic amines in the presence of AT and MA. Under optimal conditions the coefficients for the TMB–AT, PDA–AT, TMB–MA, and PDA–MA pairs vary in the limits of (1.90-3.53)·10³ M^–1.     

Micro-analytical GO/HRP bioreactor for glucose determination and bioprocess monitoring

A bi-enzymatic micro-analytical bioreactor integrated in a FIA system for glucose measurements is described. Its robustness and small dimensions (working volume of about 70 microl containing approximately 1.2 mg GO and 0.26 mg HRP) make it easy to operate. The column is based on immobilisation of glucose oxidase (GO) and horseradish peroxidase (HRP) on alkylamine controlled pore glass (CPG) beads. The column has excellent shelf life (no significant loss of activity after 1 year if kept at 4 degrees C), and a very high operational stability that was demonstrated through extensive usage for glucose determinations over 1 year period during which the column retained almost all of its activity. More importantly, this operational stability allows glucose monitoring in the culture media without a decay of signal over the experiment time and consequently no signal correction or re-calibration is needed. This high operational stability was also confirmed by continuous glucose conversion with 30% activity loss after converting quantity of glucose equivalent to 21600 FIA injections of 20 microl with 1.7 mM glucose. Such good performance is a result of an optimised immobilisation method and moreover of the implementation of in situ enzyme stabilisation strategy which consisted on promoting the instantaneous H2O2 consumption produced by the GO. This strategy has the additional advantage of allowing concomitant assay of the H2O2 based on the HAP catalysed co-oxidation of phenol-4-sulphonic acid (PSA) in the presence of 4-aminoantipyrine (4-AAP). The glucose measurements are reproducible with high precision against the standard HPLC method. Linear range and sensitivity depend on sample injection volume; the upper limit is about 1.1 g/l. Lower detection limit is 10mg/l. The column performance has been validated for E. coli and S. cerevisiae fermentation monitoring, and glucose measurements in an animal cell culture (rat Langerhans islets).     

Oxidising activity in root extracts from plants inoculated with virus or buffer that interferes with ELISA when using the substrate 3,3', 5,5'-tetramethylbenzidine

In indirect ELISA using protein A-horseradish peroxidase (HRP) as enzyme conjugate and 3,3′, 5,5′-tetramethylbenzidine (TMB) as substrate, extracts of roots of all cucumber, Chenopodium quinoa and Petunia hybrida plants previously inoculated with virus or buffer produced A₄₅₀ values up to seven-fold greater than those for comparable shoots or for extracts of roots from undisturbed, uninoculated plants, irrespective of the virus antiserum used for detection. This effect was also produced in tests in which no HRP conjugate was used, indicating that root extracts from virus-infected or physically injured plants, but not healthy uninjured plants, contain high levels of a factor able to oxidise TMB. The HRP conjugate/TMB substrate version of ELISA is therefore not reliable for detecting viruses in root extracts of herbaceous plants. In contrast, non-specific reactions were not obtained with root extracts, and viruses were reliably detected, when protein A-alkaline phosphatase was used as conjugate and p-nitrophenyl phosphate as substrate.     

Peroxidase-catalyzed co-oxidation of 3,3',5,5'-tetramethylbenzidine in the presence of substituted phenols and their polydisulfides

The steady-state kinetics of the horseradish peroxidase (HRP)-catalyzed oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) has been studied in the presence of 2-amino-4-nitrophenol (ANP), gallic acid (GA) or 4,4'-dihydroxydiphenylsulfone (DDS) and their polydisulfides poly(ADSNP), poly(DSGA), poly(DSDDS) at 20 degrees C in 10 mM phosphate buffer, pH 6.4, supplemented with 5-10% dimethylformamide. The second-order rate constants for the reactions of ANP, GA, poly(DSGA) and poly(DSDDS) with HRP-Compound I (k2) and Compound II (k3) have been determined at 25 degrees C in 10 mM phosphate buffer, pH 6.0 by stopped-flow spectrophotometry. ANP, GA and their polydisulfides strongly inhibited HRP-catalyzed TMB oxidation. Inhibition constants (Ki) and stoichiometric coefficients of inhibition (f) have been determined for these reactions. The most effective inhibitor was poly(DSGA) (Ki=1.3 microM, f=35.6). The oxidation of substrate pairs by HRP, i.e., TMB-DDS and TMB-poly(DSDDS) at pH 7.2 resulted in a approximately 8- and approximately 12-fold stimulation of TMB oxidation rates, respectively. The mechanisms of the HRP-catalyzed co-oxidation of TMB-phenol pairs are discussed.     

Cooxidation of phenol and 4-aminoantipyrin, catalyzed by polymers and copolymers of horseradish root peroxidase and Penicillium funiculosum 46.1 glucose oxidase

Polymers and copolymers of horseradish root peroxidase (HRP) and Penicillium funiculosum 46.1 glucose oxidase (GO) have been synthesized and their catalytic properties have been characterized (free and immobilized forms of each enzyme were studied). The cooxidation reaction of phenol and 4-aminoantipyrin (4-AAP), performed in an aqueous medium in the presence of equimolar amounts of GO and HRP, was characterized by effective K(M) and k(cat) of 0.58 mM and 20.9 s(-1) (for phenol), and 14.6 mM and 18.4 s(-1) (glucose), respectively. The catalytic efficiency of polymerization products (PPs) of GO (GO-PPs) depended on the extent of their aggregation. The combinations GO + HRP-PP and HRP + GO-PP, as well as the copolymer HRP*-GO-PP, proved promising as reagents for enzyme-based analytical systems. When adsorbed on aluminum hydroxide gels, GO-PPs exhibited higher catalytic activity than the non-polymeric enzyme. Maximum retention of GO-PP activity on the inorganic carrier was observed in the case of GO-PP copolymers with an activated HRP. Polymerization of HRP in the presence of a zinc hydroxide gel, paralleled by HRP-PP immobilization onto the gel, increased both the activity of the enzyme and its operational stability.     

Propyl gallate inhibition of iodide and tetramethylbenzidine oxidation catalyzed by human thyroid peroxidase

The kinetic characteristics (kcat, Km, and their ratio) for oxidation of iodide (I-) at 25 degrees C in 0.2 M acetate buffer, pH 5.2, and tetramethylbenzidine (TMB) at 20 degrees C in 0.05 M phosphate buffer, pH 6.0, with 10% DMF catalyzed by human thyroid peroxidase (HTP) and horseradish peroxidase (HRP) were determined. The catalytic activity of HRP in I- oxidation was about 20-fold higher than that of HTP. The kcat/Km ratio reflecting HTP efficiency was 35-fold higher in TMB oxidation than that in I- oxidation. Propyl gallate (PG) effectively inhibited all four peroxidase processes and its effects were characterized in terms of inhibition constants Ki and the inhibitor stoichiometric coefficient f. For both peroxidases, inhibition of I- oxidation by PG was characterized by mixed-type inhibition; Ki for HTP was 0.93 microM at 25 degrees C. However, in the case of TMB oxidation the mixed-type inhibition by PG was observed only with HTP (Ki = 3.9 microM at 20 degrees C), whereas for HRP it acted as a competitive inhibitor (Ki = 42 microM at 20 degrees C). A general scheme of inhibition of iodide peroxidation containing both enzymatic and non-enzymatic stages is proposed and discussed.     

A colorimetric-based amplification system for proteinases including MMP2 and ADAM8

We have developed a new amplification system for proteinases that is sensitive, simple, and inexpensive to run, exemplified by a horseradish peroxidase (HRP)-conjugated, dual MMP2 (matrix metalloproteinase 2) and ADAM8 (a disintegrin and metalloproteinase 8) peptide substrate assay presented herein. The HRP-conjugated substrate is attached to beads through a 6× histidine tag and then incubated with the target enzyme, cleaving the HRP reporter. This product is subsequently removed from the unreacted bound portions of the substrate by magnetic deposition of the beads. The amount of product is then quantified using a standard HRP color development assay employing 3,3′,5,5′-tetramethylbenzidine (TMB) and hydrogen peroxide (H₂O₂). This HRP amplification system represents a new approach to proteinase assays and could be applied to other enzymes, such as lipases, esterases, and kinases, as long as the unreacted substrate can be physically separated from the product and catalysis by the enzyme to be quantified is not impaired dramatically by steric hindrance from the HRP entity.     

Stabilization of the tetramethylbenzidine (TMB) reaction product: application for retrograde and anterograde tracing, and combination with immunohistochemistry

Tetramethylbenzidine (TMB) as a substrate for horseradish peroxidase (HRP) histochemistry is more sensitive than other chromogens. Its instability in aqueous solutions and ethanol, however, has limited its application. We now report a method for stabilizing TMB by incubation in combinations of diaminobenzidine (DAB)/cobalt (Co2+)/H2O2. The stabilized TMB product was unaffected by long-term exposures to ethanol, neutral buffers, and subsequent immunohistochemical staining procedures. A procedure is recommended for optimal stabilization of TMB that affords a sensitivity for demonstrating retrogradely labeled perikarya comparable to standard TMB histochemistry. The physical characteristics of the reaction product make it suitable for combination with the unlabeled antibody, peroxidase-antiperoxidase (PAP) immunohistochemical staining procedure. This was established by staining retrogradely labeled neurons in the basal forebrain with a monoclonal antibody against choline acetyltransferase. Because the stabilized TMB product exhibited a superior sensitivity over cobalt ion intensification of the DAB-based reaction product (DAB-Co), it offers a distinct advantage over previously described combination procedures.     

The Effect of Tetrazole and Its Amino Derivatives on the Kinetics of Peroxidase Oxidation of Chromogenic Substrates

The peroxidase-catalyzed oxidation of 2,2-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), o-phenylenediamine (PDA), and 3,3,5,5-tetramethylbenzidine (TMB) was found to be activated by tetrazole and 5-aminotetrazole (AT) and weakly inhibited by 1,5-diaminotetrazole. The activating action of tetrazole and AT on the PDA and TMB oxidation was clearly discompetitive and that on ABTS was non-competitive. The coefficients (degrees) of activation were determined for three substrates and two activators; they depended on the substrate type and the buffer nature and increased along with the pH growth from 6.4 to 7.2. For AT and tetrazole, the maximal values were 4140 and 800 M^–1, respectively, upon the PDA oxidation and 3570 and 540 M^–1, respectively, upon the TMB oxidation. Lower values (145 and 58 M^–1 for tetrazole and AT, respectively) were characteristic of the peroxidase oxidation of ABTS. The activation of peroxidase oxidation of the substrates by tetrazole and AT at pH 5.4 was explained by the nucleophilic nature of the activators interacting with the amino acid residues in the peroxidase active site according to the mechanism of acid–base catalysis.     

Molecular cloning, overexpression, and characterization of autophosphorylation in calcium-dependent protein kinase 1 (CDPK1) from Cicer arietinum

In plants, calcium-dependent protein kinases (CDPKs) are key intermediates in calcium-mediated signaling that couple changes in Ca²⁺ levels to a specific response. In the present study, we report the high-level soluble expression of calcium-dependent protein kinase1 from Cicer arietinum (CaCDPK1) in Escherichia coli. The expression of soluble CaCDPK1 was temperature dependent with a yield of 3–4 mg/l of bacterial culture. CaCDPK1 expressed as histidine-tag fusion protein was purified using Ni–NTA affinity chromatography till homogeneity. The recombinant CaCDPK1 protein exhibited both calcium-dependent autophosphorylation and substrate phosphorylation activities with a V _max and K _m value of 13.2 nmol/min/mg and 34.3 μM, respectively, for histone III-S as substrate. Maximum autophosphorylation was seen only in the presence of calcium. Optimum temperature for autophosphorylation was found to be 37 °C. The recombinant protein showed optimum pH range of 6–9. The role of autophosphorylation in substrate phosphorylation was investigated using histone III-S as exogenous substrate. Our results show that autophosphorylation happens before substrate phosphorylation and it happens via intra-molecular mechanism as the activity linearly depends on enzyme concentrations. Autophosphorylation enhances the kinase activity and reduces the lag phase of activation, and CaCDPK1 can utilize both ATP and GTP as phosphodonor but ATP is preferred than GTP.     

Peroxidase-Like Catalytic Activity of Ag3PO4 Nanocrystals Prepared by a Colloidal Route

Nearly monodispersed Ag₃PO₄ nanocrystals with size of 10 nm were prepared through a colloidal chemical route. It was proven that the synthesized Ag₃PO₄ nanoparticles have intrinsic peroxidase-like catalytic activity. They can quickly catalyze oxidation of the peroxidase substrate 3, 3, 5, 5-tetramethylbenzidine (TMB) in the presence of H₂O₂, producing a blue color. The catalysis reaction follows Michaelis-Menten kinetics. The calculated kinetic parameters indicate a high catalytic activity and the strong affinity of Ag₃PO₄ nanocrystals to the substrate (TMB). These results suggest the potential applications of Ag₃PO₄ nanocrystals in fields such as biotechnology, environmental chemistry, and medicine.     

Polyoxometalates as peroxidase mimetics and their applications in H2O2 and glucose detection

Polyoxometalates (H(3)PW(12)O(40), H(4)SiW(12)O(40) and H(3)PMo(12)O(40)) have been proven to possess intrinsic peroxidase-like activity for the first time, which can catalyze oxidation of the peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) by H(2)O(2) to form a blue color in aqueous solution. Among them, H(3)PW(12)O(40) (PW(12)) exhibits higher catalytic activity to TMB than natural enzyme HRP and other two POMs. In addition, H(3)PW(12)O(40)/graphene exhibited higher activity than H(3)PW(12)O(40) in this catalytic oxidation reaction due to the effect of graphene in promoting the electron transfer between the substrate and catalyst. POMs/H(2)O(2)/TMB system provides a simple, accurate approach to colorimetric detection for H(2)O(2) or glucose. The colorimetric method based on POMs showed good response toward H(2)O(2) and glucose detection with a linear range from 1.34×10(-7) to 6.7×10(-5) mol/L and 1×10(-7) to 1×10(-4) mol/L, respectively. The results showed that it is a simple, cheap, more convenient, highly selective, sensitive, and easy handling colorimetric assay.     

Oxidative modification of human low-density lipoprotein by horseradish peroxidase in the absence of hydrogen peroxide

Heme-peroxidases, such as horseradish peroxidase (HRP), are among the most popular catalysts of low density lipoprotein (LDL) peroxidation. In this model system, a suitable oxidant such as H₂O₂ is required to generate the hypervalent iron species able to initiate the peroxidative chain. However, we observed that traces of hydroperoxides present in a fresh solution of linoleic acid can promote lipid peroxidation and apo B oxidation, substituting H₂O₂.

Spectral analysis of HRP showed that an hypervalent iron is generated in the presence of H₂O₂ and peroxidizing linoleic acid. Accordingly, careful reduction of the traces of linoleic acid lipid hydroperoxide prevented formation of the ferryl species in HRP and lipid peroxidation. However, when LDL was oxidized in the presence of HRP, the ferryl form of HRP was not detectable, suggesting a Fenton-like reaction as an alternative mechanism. This was supported by the observation that carbon monoxide, a ligand for the ferrous HRP, completely inhibited peroxidation of LDL.

These results are in agreement with previous studies showing that myoglobin ferryl species is not produced in the presence of phospholipid hydroperoxides, and emphasize the relevance of a Fenton-like chemistry in peroxidation of LDL and indirectly, the role of pre-existing lipid hydroperoxides.     

Stimulation of the activity of horseradish peroxidase by nitrogenous compounds

A variety of nitrogenous compounds broaden the activity versus pH profile for the peroxidation of dianisidine catalyzed by horseradish peroxidase (HRP), but not by myeloperoxidase, chloroperoxidase, Escherichia coli hydroperoxidase I, methemoglobin, or microperoxidases. The peroxidation of dianisidine catalyzed by cytochrome c peroxidase was affected by the nitrogenous compounds, but to a lesser extent than was the action of HRP. The peroxidations of a variety of phenols by HRP exhibited broad activity versus pH profiles and were unaffected by the nitrogenous compounds. The energy of activation for the peroxidation of dianisidine by HRP was unaffected by changes of pH in the range 6.5-8.5 and was unchanged by the presence of the nitrogenous compounds. The nitrogenous compounds markedly increased Vm for the peroxidation of dianisidine by HRP, but did not change the slope of Lineweaver-Burk plots of kinetic data. These results are accommodated by a mechanism in which nitrogenous compounds hydrogen-bond to the distal histidine of HRP and in so doing raise its pK alpha. Since the acid form of the distal histidine is thought to facilitate peroxidations catalyzed by HRP by hydrogen bonding to the ferryl oxygen of compound II, raising its pK alpha broadens the activity versus pH profile for the peroxidation of anilino substrates, such as dianisidine. We propose that phenolic substrates hydrogen-bond directly to the ferryl oxygen, thus displacing the distal histidine and eliminating the possibility of being influenced by nitrogenous compounds.     

Immobilization of Horseradish Peroxidase on Multi-Wall Carbon Nanotubes and its Electrochemical Properties

Horseradish peroxidase (HRP) was immobilized on carboxylated multi-wall carbon nanotubes in the presence of a coupling reagent, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide. The immobilized HRP maintained its oxidative activity for guaiacol over a broad range of pH values (4–9). An electrode of graphite rod, 6 mm diam. was fabricated using the immobilized HRP. Cyclic voltammetry of the enzyme electrode confirmed electron transfer between the immobilized HRP and the electrode in the presence of H₂O₂ but without an added mediator or a reducing substrate.     

Human thyroid peroxidase: inhibition of iodide ion and 3,3',5,5'-tetramethylbenzidine hydrolysis by phenol antioxidants]

A comparative kinetic study on the poly(gallic acid disulfide) (poly(DSGA)) inhibition of the iodide ion oxidation and on the 2-hydroxy-3,5-di-tert-butyl-N-phenylaniline (butaminophene) inhibition of 3,3',5,5'-tetramethylbenzidine (TMB) oxidation involving human thyroid peroxidase (hTPO) and horseradish peroxidase (HRP) was performed. The inhibition processes were characterized with the inhibition constants Ki and stoichiometric inhibition coefficients f, indicating the number of radical particles perishing on one inhibitor molecule. In the case of poly(DSGA), the Ki values for the I- oxidation were 0.60 and 0.04 microM, and the coefficients f were 13.6 and 16.5 for hTPO and HRP, respectively, which evidences the regeneration and high effectiveness of the polymeric inhibitor. In the case of butaminophene, the Ki values for TMB oxidation were 38 and 46 microM for hTPO and HRP, respectively. The coefficients f were 1.33 and 1.47, respectively, to reveal that butaminophene does not regenerate. The inhibition mechanisms for I- and TMB oxidation involving the two peroxidases are discussed.     

Phage display identification of functional binding peptides against 4-acetamidophenol (Paracetamol): an exemplified approach to target low molecular weight organic molecules

Peptide-phage display has been widely used to explore protein-protein interactions, however, despite the potential range of applications the use of this technology to identify peptides that bind low molecular weight organic molecules has not been explored. In this current study, we identified a phage clone (PARA-061) displaying the cyclic 7-mer peptide sequence N' AC-NPNNLSH-CGGGS C' that binds the low molecular weight organic molecule 4-acetamidophenol (4-AAP; paracetamol). To avoid occupancy of key functional groups on the target 4-AAP molecule our panning strategy was directed against insoluble complexes of 4-AAP rather than against the target linked to a stationary support or bearing an affinity tag. To augment the panning procedure we deleted phage that also bound the 4-AAP isomers, 2-AAP and 3-AAP. The identified PARA-061 peptide-phage clone displayed functional binding properties against 4-AAP in solution, able in a peptide sequence-dependant manner to prevent the in vitro hepatotoxicity of 4-AAP and reduce ( approximately 20%) the permeability of 4-AAP across a semi-permeable membrane. Molecular dynamic simulations generated a stable binding conformation between the PARA-061 peptide sequence and 4-AAP. In conclusion, we show that a phage display library can be used to identify peptide sequence-specific clones able to modulate the functional binding of a low molecular weight organic molecule. Such peptides may be expected to find utility in the next generation of hybrid polymer-based biosensing devices.