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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.