ELECTRON MICROSCOPY

Sample

pre-translocational E. coli ribosome

Specimen Preperation
Sample Aggregation State PARTICLE
Vitrification Instrument ?
Cryogen Name ETHANE
Sample Vitrification Details rapid-freezing in liquid ethane
3D Reconstruction
Reconstruction Method SINGLE PARTICLE
Number of Particles 52181
Reported Resolution (Å) 15
Resolution Method ?
Other Details WITH THE USE OF APPROPRIATE STEREOCHEMICAL CONSTRAINTS, AN ATOMIC MODEL FITTED INTO AN EM MAP YIELDS AN ACCURACY OF 5-FOLD BETTER THAN THE NOMINAL RESOLUTION OF THE EM MAP. THE RESOLUTION OF THE ATOMIC MODEL FITTED INTO EMD-1056 (NOMINAL RESOLUTION 15.0 ANGSTROMS) IS THUS ESTIMATED TO BE BETWEEN 2-3 ANGSTROMS. REAL-SPACE REFINEMENT USING RIGID BODIES INTO EM MAP EMD-1056 (FILTERED TO A NOMINAL RESOLUTION OF 15 ANGSTROMS). RIGID BODY DEFINITION: AN AUTONOMOUS SECONDARY STRUCTURE UNIT (E.G. HELIX SEGMENT, HAIRPIN) OF THE RIBOSOMAL RNA; AN AUTONOMOUS RIBOSOMAL PROTEIN DOMAIN. THE ATOMIC MODEL USED WAS GENERATED FROM E. COLI MODELS OF X-RAY CRYSTALLOGRAPHY STRUCTURES OF RIBOSOMES FROM OTHER ORGANISMS. IN THE ABSENCE OF E. COLI MODELS, STRUCTURES WERE DERIVED DIRECTLY FROM THE X-RAY CRYSTALLOGRAPHY STRUCTURES OF RIBOSOMES FROM OTHER ORGANISMS.
Refinement Type
Symmetry Type POINT
Map-Model Fitting and Refinement
ID 1
Refinement Space REAL
Refinement Protocol OTHER
Refinement Target Minimization of number of poor van der Waals contacts and maximation of correlation coefficient
Overall B Value ?
Fitting Procedure ?
Details REFINEMENT PROTOCOL--CNS implementation of RSRef
Data Acquisition
Detector Type KODAK SO-163 FILM
Electron Dose (electrons/Å2) 20
Imaging Experiment
Date of Experiment 2002-07-01
Temprature (Kelvin)
Microscope Model FEI TECNAI F20
Minimum Defocus (nm) 1.1
Maximum Defocus (nm) 3.8
Minimum Tilt Angle (degrees) 0
Maximum Tilt Angle (degrees) 0
Nominal CS 2.0
Imaging Mode BRIGHT FIELD
Specimen Holder Model ?
Nominal Magnification 50000
Calibrated Magnification 49696
Source FIELD EMISSION GUN
Acceleration Voltage (kV) 200
Imaging Details ?
Imaging Experiment
Task Software Package Version
MODEL FITTING CNS ?
RECONSTRUCTION SPIDER ?
Image Processing
CTF Correction Type CTF Correction Details Number of Particles Selected Particle Selection Details
. CTF correction of 3D-maps by Wiener filtration