A New Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy Method for the Study of Proteins in Solution

Oberg, Keith A.; Fink, Anthony L.

doi:10.1006/abio.1997.2486

Cited by 135 publications

(130 citation statements)

References 29 publications

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“…Raw spectra were further processed to enhance the component bands by second derivative analysis and Fourier self-deconvolution. Secondary-structure analysis was performed by using curve-fit spectra, as described (28)(29)(30)(31)(32). This approach has been shown to provide accurate secondary-structure analysis for different kinds of proteins of known structure (31,33,34).…”

Section: Methodsmentioning

confidence: 99%

Tau filaments from human brain and from in vitro assembly of recombinant protein show cross-β structure

Berriman

Serpell

Oberg

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

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Abnormal filaments consisting of hyperphosphorylated microtubule-associated protein tau form in the brains of patients with Alzheimer's disease, Down's syndrome, and various dementing tauopathies. In Alzheimer's disease and Down's syndrome, the filaments have two characteristic morphologies referred to as paired helical and straight filaments, whereas in tauopathies, there is a wider range of morphologies. There has been controversy in the literature concerning the internal molecular fine structure of these filaments, with arguments for and against the cross-␤ structure demonstrated in many other amyloid fibers. The difficulty is to produce from brain pure preparations of filaments for analysis. One approach to avoid the need for a pure preparation is to use selected area electron diffraction from small groups of filaments of defined morphology. Alternatively, it is possible to assemble filaments in vitro from expressed tau protein to produce a homogeneous specimen suitable for analysis by electron diffraction, x-ray diffraction, and Fourier transform infrared spectroscopy. Using both these approaches, we show here that native filaments from brain and filaments assembled in vitro from expressed tau protein have a clear cross-␤ structure.

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Section: Methodsmentioning

confidence: 99%

Tau filaments from human brain and from in vitro assembly of recombinant protein show cross-β structure

Berriman

Serpell

Oberg

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

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285

241

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“…The thin films prepared in this manner were transparent, indicating that no substantial aggregation of the protein occurred during sample preparation. If extensive protein aggregation/denaturation had occurred, it would have resulted in films with a frosted appearance [16]. For each spectrum, 1024 scans were accumulated at 2-cm Ϫ1 resolution and ratioed against that of a clean internal reflection element.…”

Section: Tyrosine N-acetyl-dl-tryptophan Amide N-acetyl-l-tryptophamentioning

confidence: 99%

Papaya glutamine cyclase, a plant enzyme highly resistant to proteolysis, adopts an all‐β conformation

Oberg

Ruysschaert

Azarkan

et al. 1998

European Journal of Biochemistry

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Glutamine cyclases catalyse the conversion of L-glutaminyl-peptides into 5-oxoprolyl-peptides with the concomitant liberation of ammonia. We report here biophysical characterisation of the glutamine cyclase present in the laticiferous cells of the plant Carica papaya. After purification to near homogeneity, this enzyme was subjected to limited proteolysis and found to exhibit a high resistance to degradation and nicking. The structural reasons for this property were examined using circular dichroism and infrared spectroscopies. By combining the analyses of the infrared and CD spectra of papaya glutamine cyclase, its susceptibility to proteolysis, and its hydrogen-deuterium exchange characteristics, we conclude that this protein contains extensive β-sheet structure and is likely to have only short immobile loops connecting its β-strands.Keywords : secondary structure ; circular dichroism; infrared spectroscopy ; limited proteolysis; hydrogendeuterium exchange.The aerial parts of the tropical plant Carica papaya contain laticiferous cells which constitute a particularly rich source of cysteine proteinases. The well-documented proteinases papain, glycyl endopeptidase, chymopapain and caricain are all secreted by these cells [1Ϫ4]. Besides these proteinases, minor protein constituents including two chitinases [5,6], a glutamine cyclase [7] and a serine proteinase inhibitor [8] have been isolated and partially characterised.Although they are synthesised as inactive preproenzymes, the four papaya proteinases exist in their mature forms in the laticifers [9] because freshly collected papaya latex exhibits full proteolytic activity. The catalytic competence of papain-like cysteine proteinases requires the generation of a catalytic-site imidazolium-thiolate ion pair and the protonic dissociation of a carboxylic acid function with a pKa value close to 4 [10], which controls the ion pair geometry. Three elements help sustain full proteolytic activity in the papaya laticiferous cells: (a) the absence of cysteine proteinase inhibitors, (b) the presence of a high concentration (about 20 mM) of low molecular-mass thiol-containing compounds, and (c) a buffering capacity that maintains the pH around 5.2. From a physiological point of view, papaya laticifers may therefore be regarded as an extreme milieu. The structural reasons for the ability of the latex enzymes to elude -A-benzoyl-DL-arginine-p-nitroanilide; BTPNA, N-A-benzoyl-DL-tyrosine-p-nitroanilide. Enzymes. Glutamine cyclases (EC 2.3.2.5); papain (EC 3.4.22.2) ; glycyl endopeptidase (EC 3.4.22.25); chymopapain (EC 3.4.22.6) ; caricain (EC 3.4.22.30). rapid in vivo degradation through autolysis and proteolysis has not previously been examined.Within this context, we present a study of a recently purified glutaminyl-peptide cyclotransferase from the laticifers of C. papaya (referred to here as papaya glutamine cyclase, or PQC). This enzyme catalyses the conversion of L-glutaminyl-peptides into 5-oxoprolyl-peptides with concomitant liberation of ammonia [11], as shown...

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“…44 ATR-IR has the advantage of reduced sample preparation time, and is relatively impervious to variations in sample thickness compared to TIR, making collection of high-quality spectra easier. 30,44,46 The objective of our study was to investigate the utility of previously built partial least squares (PLS) models for quantifying IgG for a new set of samples and to compare the performance of TIR and ATR-IR spectroscopic approaches (in combination with multivariate analysis) as the basis to predict IgG levels in bovine serum, and to identify FTPI in dairy calves.…”

Section: Introductionmentioning

confidence: 99%

Quantification of bovine immunoglobulin G using transmission and attenuated total reflectance infrared spectroscopy

et al. 2015

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Abstract. In this study, we evaluated and compared the performance of transmission and attenuated total reflectance (ATR) infrared (IR) spectroscopic methods (in combination with quantification algorithms previously developed using partial least squares regression) for the rapid measurement of bovine serum immunoglobulin G (IgG) concentration, and detection of failure of transfer of passive immunity (FTPI) in dairy calves. Serum samples (n = 200) were collected from Holstein calves 1-11 days of age. Serum IgG concentrations were measured by the reference method of radial immunodiffusion (RID) assay, transmission IR (TIR) and ATR-IR spectroscopy-based assays. The mean IgG concentration measured by RID was 17.22 g/L (SD ±9.60). The mean IgG concentrations predicted by TIR and ATR-IR spectroscopy methods were 15.60 g/L (SD ±8.15) and 15.94 g/L (SD ±8.66), respectively. RID IgG concentrations were positively correlated with IgG levels predicted by TIR (r = 0.94) and ATR-IR (r = 0.92). The correlation between 2 IR spectroscopic methods was 0.94. Using an IgG concentration <10 g/L as the cut-point for FTPI cases, the overall agreement between TIR and ATR-IR methods was 94%, with a corresponding kappa value of 0.84. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for identifying FTPI by TIR were 0.87, 0.97, 0.91, 0.95, and 0.94, respectively. Corresponding values for ATR-IR were 0.87, 0.95, 0.86, 0.95, and 0.93, respectively. Both TIR and ATR-IR spectroscopic approaches can be used for rapid quantification of IgG level in neonatal bovine serum and for diagnosis of FTPI in dairy calves.

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A New Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy Method for the Study of Proteins in Solution

Cited by 135 publications

References 29 publications

Tau filaments from human brain and from in vitro assembly of recombinant protein show cross-β structure

Tau filaments from human brain and from in vitro assembly of recombinant protein show cross-β structure

Papaya glutamine cyclase, a plant enzyme highly resistant to proteolysis, adopts an all‐β conformation

Quantification of bovine immunoglobulin G using transmission and attenuated total reflectance infrared spectroscopy

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