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Table 2 Secondary Structure Analysis of Purified U24 by CD Spectroscopy

From: Overexpression and purification of U24 from human herpesvirus type-6 in E. coli: unconventional use of oxidizing environments with a maltose binding protein-hexahistine dual tag to enhance membrane protein yield

U24 samplea Secondary Structure Fractionb NRMSDc
  αR αD βR βD T U  
C41(DE3) 0.412 0.208 0.006 0.032 0.113 0.234 0.150
C41(DE3) + TCEP 0.367 0.212 0.018 0.035 0.127 0.243 0.143
Origami 0.379 0.223 0.023 0.032 0.120 0.222 0.130
Origami + TCEP 0.341 0.201 0.021 0.041 0.134 0.256 0.130
SHuffle 0.411 0.204 0.003 0.03 0.117 0.231 0.156
SHuffle + TCEP 0.401 0.212 0.013 0.032 0.112 0.239 0.147
  1. aU24 protein that had been isolated from various E.coli cell strains was reconstituted in 10 mM Tris·HCl, 10 mM NaCl, 10 mM SDS, pH 7.5 and far-UV CD was run (260-195 nm) in the presence and absence of tris(2-carboxyethyl)phosphine (TCEP) reducing agent.
  2. bFractions of secondary structure were determined by combining the software analysis results of the CONTIN/LL, SELCON3 and CDSSTR programs [27] using the SMP56 reference data set. Structural classes are given as: αR, regular α-helix; αD, distorted α-helix; βR, regular β-strand; βD, distorted β-strand; T, turns; U, unordered.
  3. cNormalized Root-Mean-Square Deviation. NRMSD is defined as Σ[(θexp - θcal)2/(θexp)2]1/2, summed over all wavelengths, and where θexp and θcal are, respectively, the experimental ellipticities and ellipticities of the back-calculated spectra for the derived structure [27, 35]. It has been suggested [36] that experimental and calculated spectra are in good agreement if NRMSD < 0.1, are similar if 0.1 < NMRSD < 0.2, and are in poor agreement if NRMSD > 0.2.