Deconvolution of the circular dichroism spectra of proteins: The circular dichroism spectra of the antiparallel β‐sheet in proteins
ABSTRACT A recently developed algorithm, called Convex Constraint Analysis (CCA), was successfully applied to determine the circular dichroism (CD) spectra of the pure β-pleated sheet in globular proteins. On the basis of X-ray diffraction determined secondary structures, the original data set used (Perczel, A., Hollosi, M., Tusnady, G. Fasman, G.D. Convex constraint analysis: A natural deconvolution of circular dichroism curves of proteins, Prot. Eng., 4:-669–679, 1991), was improved by the addition of proteins with high β-pleated sheet content. The analysis yielded CD curves of the pure components of the main secondary structural elements (α-helix, antiparallel β-pleated sheet, β-turns, and unordered conformation), as well as a curve attributed to the “aromatic contribution” in the wavelength range of 195–240 nm. Upon deconvolution the curves obtained were assigned to various secondary structures. The calculated weights (percentages determining the contributions of each pure component curve in the measured CD spectra of a given protein) were correlated with the X-ray diffraction determined percentages in an assignment procedure and were evaluated. The Pearson product correlation coefficients (R) are significant for all five components. The new pure component curves, which were obtained through deconvolution of the protein CD spectra alone, are promising candidates for determining the percentages of the secondary structural components in globular proteins without the necessity of adopting an X-ray database. The CD spectrum of the CheY protein was interesting because it has the characteristic shape associated with the α-helical structure, but upon analysis yielded a considerable amount of β-sheet in agreement with the X-ray structure. © 1992 Wiley-Liss, Inc.
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ABSTRACT: The acid proteinase penicillopepsin has been isolated from the culture filtrate of the mould Penicillium janthinellum, grown in submerged culture in a 1500 l fermentor. After concentrating the enzyme by adsorption on diethylaminoethylcellulose, it was purified by chromatography on aminoethylcellulose and phosphocellulose. The yield of the purified enzyme was about 2.6 g (37% recovery). It was shown to be homogeneous on acrylamide gel. Crystals suitable for X-ray analysis were prepared from the pure enzyme. Both the N- and the C-terminal amino acids appear to be alanine, although N-terminal serine has also been found in varying amounts. The purified enzyme is stable to prolonged exposure in the pH range 2.2–6.0, and at pH 4.9 retains 100% activity for 1 h at 55°. The crystals retain full activity at room temperature for many weeks.Canadian journal of biochemistry 05/1970; 48(4):425-31.
- Biopolymers 08/1987; 26(7):1115-24. · 2.88 Impact Factor
- Methods in Enzymology 02/1973; 27:675-735. · 2.00 Impact Factor