Splitting the characters of string

For example I have a string that is, aatcgatcaagtca and I want to split it into four letters each that is,aatc,atcg,tcga,cgat and so on.

Answer 1

[KSSV]

str = 'aatcgatcaagtca' ;
iwant = [str(1:end-3)' str(2:end-2)' str(3:end-1)' str(4:end)'] ;

There could be more elegant way...