perl '-M5;@ar[map { ord } split "","\0ARNDBCEQZGHILKMFPSTWYV"] = 0..127' -alpe '($_=$F[0])=~s/(.)/($ar[ord $1])." "/ge' input.txt
# or
perl '-M5;@ar[map { ord } split "","\0ARNDBCEQZGHILKMFPSTWYV"] = 0..127' -alpe '($_=$F[0])=~s/(.)/(defined $ar[ord $1] ? $ar[ord $1] : $1 )." "/ge' input.txt