These results clearly demonstrate that unfolding of aFGF in STCA proceeds with the accumulation of an intermediate state(s) resembling the molten globule (MG).

(a) 0% w/v STCA, (b) 5% w/v STCA, and (c) 50% w/v STCA. Recombinant aFGF was prepared from transformed Escherichia coli BL21(DE3)pLysS. [Fig.4(B)].4(B)]. Sivaraman T, Kumar TKS, Jayaraman G, Yu C. The mechanism of 2,2,2-trichloroacetic acid-induced protein precipitation. The protein precipitation effects of TCA were studied on four proteins [lysozyme, acidic fibroblast growth factor (aFGF), carbonic anhydrase, and bovine serum albumin] with varying isoelectric points and molecular masses. Protein Science : A Publication of the Protein Society, sodium dodecyl sulfate polyacrylamide gel electrophoresis. In addition, the wavelength of maximum emission of the dye shifts by about 10 nm from 506 nm to 496 nm when the protein is treated with 5% w/v STCA. Hsieh SY, Zhuang FH, Wu YT, Chen JK, Lee YL. Results of the 1-anilino-8-napthalene sulfonate (ANS) and size-exclusion chromatography, obtained using acidic fibroblast growth factor (aFGF), show that a stable molten globule-like partially structured intermediate accumulates maximally in 5% (w/v) of trichloroacetate. PMC legacy view Owing to the high content of arginine and lysine residues in aFGF, we opted to probe the conformational flexibility of the partially structured intermediate state(s) that accumulates in 5% (w/v) STCA. It is important to mention that such partially unfolded intermediate(s) also accumulate in the STCA-induced unfolding pathway of other proteins, such as lysozyme (Supporting Fig. Labeled 15NH4Cl and D2O were purchased from Cambridge Isotope Laboratories. [Fig.7(A,B)].7(A,B)]. Carpentier SC, Witter E, Laukens K, Deckers P, Swennen R, Panis B. Residues that show significant decrease in intensity and chemical shift perturbation in presence of 5% w/v STCA are depicted in green. Li X, Xu S, Pan C, Zhou H, Jiang X, Zhang Y, Ye M, Zou H. Enrichment of peptides from plasma for peptidome analysis using multiwalled carbon nanotubes. Blank corrections were made in all of the spectra using 10 mM phosphate buffer containing 100 mM NaCl. [Fig.6(A)].6(A)]. It should be important to mention that the percentage of protein(s) precipitated in various concentrations of TCA is independent of the protein concentration (in the range of 5 to 250 M) used. Of these acids, only TFA showed a strong tendency to cleave the protein [Fig. NMR resonance assignments of aFGF in its native conformation are available, and therefore structural changes that occur as a function of increasing concentrations of STCA can be conveniently monitored based on the 1H-15N chemical shift perturbation observed in the 2D 1H-15N HSQC spectra. All NMR experiments were performed on a Bruker Avance-700 MHz NMR spectrometer equipped with a cryoprobe at 25C. Biological processes and functions of proteins with long disordered regions. S2). The acid(s) treated proteins solutions were incubated at 25C for 1 h. The precipitated proteins samples were pelleted down by centrifugation at 12,000 rpm for 20 min. Fluorescence measurements were made at a protein concentration of 0.1 mg/mL in 10 mM phosphate buffer containing 100 mM NaCl. The flow rate of the eluent was set at 1 mL/min. The 1H-15N HSQC spectrum is a fingerprint of the backbone conformation of a protein under given experimental conditions.351H-15N HSQC of aFGF in 0% (w/v) STCA is well-dispersed indicating that the protein is well-structured in its native conformation [Fig. Far UV circular dichroism (CD) spectrum of aFGF in its native conformation shows a strong positive ellipticity band (between 225 and 230 nm) typical of -barrel proteins [Fig. Size exclusion chromatogram of the protein sample extracted in 500 mM bicarbonate showed only a major peak (retention time 81) corresponding to the native conformation of aFGF [Fig. In this context, the lower tendency of unstructured/disordered proteins to precipitate in TCA can result in failure to detect a number of intrinsically disordered proteins that play crucial roles in cell signaling and regulation. Proteolysis as a measure of the free energy difference between cytochrome c and its derivatives. [Fig.6(A)].6(A)]. These residues are mostly located in -strand I, -strand II, -strand VIII, and the loop connecting -strands VIII and IX, and -strand XI [Fig. However, protein solutions containing 1530% STCA turned mildly turbid after 4 h of incubation at room temperature. The concentration of the protein sample used was 0.1 mM in 90% H2O and 10% D2O prepared in 10 mM phosphate buffer containing 100 mM NaCl. The broad minor peak (with an average retention time of 40 min) observed in the FPLC profile possibly represents the population of oligomeric species formed in the TCA-induced protein precipitate. [Fig.55(B)]. Ahmad A, Madhusudanan KP, Bhakuni V. Trichloroacetic acid and trifluoroacetic acid-induced unfolding of cytochrome c: stabilization of a native-like folded intermediate. ; and (4) What is the general mechanism underlying TCA-induced protein precipitation? Elution of the protein (at 25C) was carried out using 10 mM phosphate buffer containing 100 mM NaCl. 8600 Rockville Pike The TCA precipitation profile of aFGF, monitored using SDS PAGE, is also bell-shaped [Fig. The authenticity of the truncated sample was verified by ES-Mass analysis. Arunkumar AI, Kumar TKS, Kathir KM, Srisailam S, Wang HM, Leena PS, Chi YH, Chen HC, Wu CH, Wu RT, Chang GG, Chiu IM, Yu C. Oligomerization of acidic fibroblast growth factor is not a prerequisite for its cell proliferation activity. Undigested aFGF yields a band on SDS-PAGE, which corresponds to a molecular mass of about 16 kDa [Fig. 1H-15N chemical shift perturbation data obtained using NMR spectroscopy indicate that interactions stabilizing the -strands at the N- and C- terminal ends (of aFGF) are disrupted in the trichloroacetate-induced MG-like state. TCA is significantly less effective in precipitating unfolded states of proteins. [Fig.2(A)].2(A)]. Panel (C) Crosspeak intensity of residues in the 1H-15N HSQC spectrum of aFGF obtained in the presence of 5% w/v STCA. Isaacson T, Damasceno CM, Saravanan RS, He Y, Catala C, Saladie M, Rose JK. The site is secure. (a) 0% w/v STCA, (b) 5% w/v STCA, and (c) 50% w/v STCA. Panel (A) Fluorescence spectrum of aFGF, (a) extracted in 10 mM tris (pH 7.5), and (b) extracted in 10 mM tris (pH 7.5) containing 500 mM sodium bicarbonate. Ishida T, Kinoshita K. Prediction of disordered regions in proteins based on the meta approach. The secondary structural elements in aFGF include 12 beta strands arranged into a -trefoil motif. aFGF, in its native conformation (at pH 7.0), elutes as a single peak with an elution time of 83 1.0 min [Fig. All protein samples were prepared in 10 mM phosphate buffer (pH 7.0) containing 100 mM NaCl.

Learn more The Lane-1 represents the trypsin digestion products after various time periods of incubation of native aFGF with trypsin. Changes in the emission intensity at 520 nm and the shift in wavelength emission maximum on ANS are represented in closed and open circles, respectively. In this context, in this study, we make an attempt to provide a comprehensive understanding of the mechanism underlying the TCA-induced protein precipitation. [Fig.1(B)].1(B)]. Panel (A) SDS-PAGE analysis of the TCA-induced precipitation of lysozyme, aFGF, carbonic anhydrase, and BSA. These results suggest that acidic property of TCA and the trichloroacetate moiety are both important for inducing protein precipitation. The potency of an acid to precipitate proteins appears to depend not only on the nature of the anion but also on its ability to stabilize the precipitation-competent intermediate(s). de Roos B, Duthie SJ, Polley AC, Mulholland F, Bouwman FG, Heim C, Rucklidge GJ, Johnson IT, Mariman EC, Dnaiel H, Elliott RM. The results discussed so far clearly suggest that TCA-induced protein precipitation is a reversible association reaction. Trichloroacetic acid-induced molten globule state of aminoacylase from pig kidney. TCA-induced protein precipitation curves are U-shaped and the shape of the curve is observed to be independent of the physicochemical properties of proteins. [Fig.6(B-b)].6(B-b)]. Such precipitation-competent intermediate(s) plausibly do not accumulate in the unfolding pathway(s) of some of other acids, and therefore these acids are unable to mimic the protein-precipitation action of TCA. The column was equilibrated with two-bed volumes of the buffer (10 mM phosphate buffer containing 100 mM of NaCl) at the appropriate concentration of STCA (w/v). The precipitation efficiency of various halogenated derivatives of acetic acid was examined to understand the role of the trichloroacetate moiety in inducing protein precipitation [Fig. Development and application of a two-phase, on-membrane digestion method in the analysis of membrane proteome. Received 2008 Sep 22; Revised 2009 Feb 23; Accepted 2009 Feb 25. protein precipitation, NMR spectroscopy, molten globule-like state(s), protein isolation, proteomics, fibroblast growth factors. Similar trends were observed using lysozyme (Supporting Fig. The https:// ensures that you are connecting to the In our opinion, the mechanism proposed in this study will provide valuable clues for the development of efficient protocols to capture the entire proteome. Intrinsic disorder and functional proteomics. The results of the ANS binding and the SEC experiments analyzed in conjunction, clearly suggest that a MG-like intermediate state(s) maximally accumulates in 5% (w/v) STCA. Sample extraction techniques for enhanced proteomic analysis of plant tissues. Panel (B)The percentage of TCA-induced protein precipitation of lysozyme (open circle), aFGF (filled square), carbonic anhydrase (open square), and BSA (open triangle) was measured based on the intensity (after Coomassie blue staining) of the bands of the corresponding proteins on the polyacrylamide gel.

The spectra were processed on a Windows workstation using Xwin-NMR and Sparky softwares.39, National Library of Medicine about navigating our updated article layout.

Time-dependent trypsin digestion of the proteins in their native (at pH 7.0) and partially unfolded (in 5% (w/v) STCA) states of aFGF was monitored by SDS-PAGE analysis. [Fig.3(B)].3(B)]. S100A13-lipid interactions-role in the non-classical release of the acidic fibroblast growth factor. These results clearly suggest that the acid nature of TCA does not solely contribute to its protein precipitation property [Fig. hurana R, Gillespie JR, Talapatra A, Minert LJ, Ionescu-Zanetti C, Millet I, Fink AL. Desalting of the purified protein was achieved by ultrafiltration using an Amicon set-up. Panel (B) The percentage of protein precipitated in TCA (open circle), dichloroacetic acid (filled circle), perchloric acid (open square), hydrochloric acid (filled square), tribromoacetic acid (filled triangle), trifluoroacetic acid (open triangle), and sodium trichloroacetate (X), was measured based on the intensity (of the Coomassie blue stained) of the 16 kDa protein band (on the polyacrylamide gel). [Fig.6(B-c)].6(B-c)]. These results show that STCA is a protein denaturant, and the unfolding of aFGF is complete in concentrations of STCA greater than 20% w/v [Fig. To examine this aspect, aFGF precipitated using 30% w/v TCA was redissolved in 10 mM tris buffer (pH 7.5) containing different concentrations of sodium bicarbonate. Protein precipitation curves obtained by monitoring the intensity of the Coomassie-stained protein bands on SDS gels are bell-shaped [Fig. Uniform 15N labeling aFGF was achieved using M9 minimal medium containing 15NH4Cl. At low concentrations, the negatively charged tricholoroacetate ions plausibly trigger protein unfolding by disrupting the electrostatic interactions that stabilize the native conformation of proteins. Tanford C. Cohesive forces and disruptive reagents. The expressed proteins were purified on a heparin-sepharose affinity column over a NaCl gradient (01.5M). The dye exhibits weak binding to both the native and extensively unfolded states of proteins.19,20 However, it binds quite strongly to solvent-accessible hydrophobic pockets in stable intermediates such as the molten globule state(s).20 In this context, the binding affinity of aFGF to ANS was monitored at different concentrations of STCA (090% w/v) [Fig. Subsequently, several other studies suggested that the acidic nature of TCA is important for the conformational changes that trigger protein precipitation.1921 However, the mechanism by which TCA precipitates proteins is not clearly understood.



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