I faced a strange issue while I was trying to run CCP4-chainsaw. I used EBI-Clustal omega to prepare the desired alignement. Next, I copied the output into a text file and renamed it to alignment.aln. When I chose this file in chainsaw it gave me back this kind of error:
format error in ALN/Clustal file
No CLUSTAL keyword
This is the first line of my file : CLUSTAL O(1.2.4) multiple sequence alignment
I also typed CLUSTAL W instead of CLUSTAL O but ccp4 gave me the same error message.
Any suggestion will be appreciated.