in reply to cleaving a sequence with specific alphabets

Like this (before a K or R not followed by P) 

print for split '(?=[KR][^P])', 
'APADPKGSTIDRPDAARTLTVHKCEQTDTRGVKEGTRNEDPQAECKPVSDVEFTITKLNVD';;

APADP
KGSTIDRPDAA
RTLTVH
KCEQTDT
RGV
KEGT
RNEDPQAECKPVSDVEFTIT
KLNVD

[download]

Or maybe like this (After a K or R not followed by P): 

print for split '(?<=[KR](?!P))', 
'APADPKGSTIDRPDAARTLTVHKCEQTDTRGVKEGTRNEDPQAECKPVSDVEFTITKLNVD';;

APADPK
GSTIDRPDAAR
TLTVHK
CEQTDTR
GVK
EGTR
NEDPQAECKPVSDVEFTITK
LNVD

[download]
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