eSpCas9(1.1) is an engineered RNA-guided nuclease derived by structure-guided mutagenesis from the naturally occurring Cas9 endonuclease from Streptococcus pyogenes. It contains the amino acid substitutions K848A, K1003A and R1060A, resulting in reduced off-target effects compared to wild-type Cas9, but maintains robust on-target cleavage when targeted to a genomic target site of interest using a guide RNA (gRNA) (PMID:26628643).
