Method for properly accounting for CTF averaging - all files

Oct. 4, 1999

This protocol is used to average several tubes of several different helical symmetries. It involves
1) reindexing all tubes to a common helical symmetry
2) determining backround (ice) FFTs and reindexing them to a common symmetry
3) adding ctf values to reindexed files by "reindexing" ctf
4) adding all Big G files by vector addition, so that signal is allowed to accumulate over "noise"
5) Near and far sides kept separate until very end so that near/far stats can be determined and quality of data assessed.

Assumed- already have fitted all near/far averaged little-g files to a common symmetry and reference. (ie have made tubename.hlxshiftlg control files)

Assumed- already have made ice file stuff

Assumed - already have optimised CTF for each tube

Commands you enter are in red courier

Output files are in blue.

 
 

  Run ssadd.com on ctfb{tubename}ac300.nea and .far files:

ssadd.com {tubename}ac300.nea

ssadd.com {tubename}ac300.far
 
 

Makes ctfb{tubename}ac300add.nea and .far files.

These files have amplitudes multiplied by |CTF|, and backgrounds squared and multiplied by |CTF|. The ctf column is replaced by (ctf)^2.

The background will not be used. Could therefore also run this on ctf{tubename}ac300 files.

The CTF will also not be used.
 
 
 
 

2 Run farfliplim.com to "flip" far side. (ie add 180 deg to phase if n is odd)
 
 

farflip.com ctf{tubename}ac300add
 
 

Outputs file ctf{tubename}ac300flip.far file.
 
 

3 Edit hlxfb.cnt file to work on files created in steps 2 and 3.

Output files ctf{tubename}ac300nea.lg2

                       ctf{tubename}ac300farflip.lg2
 
 

hlxfb-ascii hlxfb
 
 

4 Reindex .lg2 files to common symmetry, using already-created littleg_reindex.com

Output files ctf{tubename}ac300near.lg2

                      ctf{tubename}ac300farflipr.lg2
 
 

ltlg_reindex.com ctf{tubename}ac300nea

ltlg_reindex.com ctf{tubename}ac300farflip
 
 

5 Edit {tubename}.hlxshftlg to work on files created in step 5.

Save as {tubename}ac300near.hlxshftlg and {tubename}ac300farflipr.hlxshftlg.

Output files ctf{tubename}ac300nearshft.lg2

                       ctf{tubename}ac300farfliprshft.lg2
 
 

hlxshftlg.com {tubename}ac300near

hlxshftlg.com {tubename}ac300farflipr
 
 

6 Edit and run matchltlg.com to match reindexed little g files with reference file.

Run on both nea and far files.

       matchltlg.com

Outputs ctf{tubename}ac300nearshftm.lg2

                ctf{tubename}ac300farfliprshftm.lg2

Purpose: 1) Ensures that all layer lines will work in reverse Fourier-Bessel transform

                  2) Makes radius of tube match that of reference tube.
 
 

7 Edit hfbr.cnt to work on reindexed, shifted, matched little-g near and far files.

hlxfbr-ascii hfbr

Output files: ctf{tubename}ac300nea.cor

                       ctf{tubename}ac300far.cor
 
 

8 Run convavg.com to convert above files to Unwin Big G format.

convavg.com ctf{tubename}ac300nea

convavg.com ctf{tubename}ac300far

Output files: ctf{tubename}ac300neaun.cor

                       ctf{tubename}ac300farun.cor
 
 

9 Edit above .cor files with emacs: Use "replace" command to replace AVG with NEA and FAR as appropriate.
 
 

10 Edit ctfplotreindex.cnt file - use same parameters as from ctfplot.cnt for particular tube. Add proper helical symmetry info.

ctfplotreindex.com

Output files: ctf{tubename}ac300neaunc.cor

                        ctf{tubename}ac300farunc.cor

Purpose -adds ctf column to files, should be proper ctf according to original helical symmetry.
 
 

11 Now start work on ice files

Edit {tubename}.hlx file to extract ice .fft rather than tube .fft file.

hlxfl

Output: {tubename}ice.nea

               {tubename}ice.far
 
 

12 Edit ctfplot.cnt file to work with ice nea and far files.

ctfplotr.com

Generates ctf{tubename}ice.nea and .far files
 
 

13 Run nfadd to add nea and far sides and multiply by ctf.

\public\bin\rice\nfadd

ctf{tubename}ice.nea

ctf{tubename}ice.far

ctf{tubename}ice.avg

1 1 0.0

Generates ctf{tubename}ice.avg
 
 

14 Edit hlxfb.cnt to work with above lim file, and make little g file.

hlxfb-ascii hlxfb

Generates ctf{tubename}ice.lg2
 
 

15 Run ltlg_reindex.com to reindex above little-g file.

ltlg_reindex.com ctf{tubename}ice.lg2

Generates ctf{tubename}icer.lg2
 
 

16 Create {tubename}ice.hlxshftlg to shift little-g file. [OPTIONAL]

hlxshftlg.com {tubename}ice

Generates ctf{tubename}iceshft.lg2
 
 

17 Edit matchltlg.com to match ice and reference layer lines

matchltlg.com

Generates ctf{tubename}iceshftm.lg2
 
 

18 Edit hfbr.cnt to work with matched little g file

hlxfbr-ascii hfbr

Generates ctf{tubename}ice.cor
 
 

19 Run convavg.com to convert to Unwin's format Big G file

convavg.com ctf{tubename}ice

Generates ctf{tubename}iceun.cor
 
 

20Edit bkgadd.cnt to add background column. Start with scale factor 1.

bkgadd.com

Check log file and adjust scale factor accordingly. Re-run.

Generates ctfb{tubename}neaunc.cor

                     ctfb{tubename}farunc.cor
 
 

21 Run ctfsqr - replaces ctf and bkg with ctf2 and bkg2

ctfsqr

Generates cctfb{tubename}neaunc.cor

                     cctfb{tubename}farunc.cor
 
 

22 Edit tubeadd.cnt file for number of tubes and each tube's scale factor.

tubeadd.com

Generates ctfbavgfar.cor

                    ctfbavgnea.cor
 
 

23 Edit divtcfbp1.com to divide amplitudes by ctf2. Also eliminates points below snc cutoff.

divctfbp1.com

Generates ctfbavgfar.lim

                     ctfbavgnea.lim
 
 

24 Edit ctfavg.nfstat to determine near/far phase residuals for various resolution shells.

nfstat.com ctfavg

Generatesnfstat.log file. Examine log file for results.
 
 

25 Edit twofold.cnt file. Run hlx2fld to determine % of data included in various resolution shells.

hlx2fld twofold
 
 

26 Repeat steps 23-25 until desired snc cutoff determined. Note % data included in shells - this is important for determining snc cutoff of near/far averaged file
 
 

27 Run nfadd to average near and far averaged files.

/public/bin/rice/nfadd

Generates ctfbavgall.cor
 
 

28 Run divctfbp1.com on ctfbavgall.cor. Run hlx2fld. Repeat until desired % data inclusion is reached.

Generates ctfbavgall.lim
 
 

29 Finally, edit htrunc.com to truncate data beyond set resolution.

htrunc.com

Generates ctfbavgall12A.lim

Use this file to make little g file and eventual map.