(A) Construction of Sumo-mCherry conjugated with peptide CSTSMLKAC. Peptides were mutated at 3′ end of mCherry cDNA and mCherry-peptides were cloned into the pE-SUMO vector. The molecular size and isoelectric point (pI) were calculated 40 kDa and 5.8, respectively. (B) Western analysis in post-ischemic cardiac tissues with an anti-mCherry antibody showed that a greater amount of protein complex was delivered to the ischemic left ventricle (LV) by the CSTSMLKAC peptide compared to negative controls (Upper panel). Lane 1–5, ischemic heart tissue samples from mice injected with PBS (Lane 1), Sumo-mCherry (vehicle) (Lane 2), Sumo-mCherry-STSMLKA (Lane 3), Sumo-mCherry-CSTSMLKAC (Lane 4), and Sumo-mCherry-scrambled peptide (Lane 5). Coomassie blue staining of the gel (lower panel) showed that each well was loaded with a comparable amount. (C) Quantitative ELISA analysis showed that significantly more Sumo-mCherry was delivered in mouse cardiac tissues by the CSTSMLKAC peptide compared with the negative controls: vehicle, STSMLKA, and the scrambled peptide (all p<0.05). In all groups except STSMLKA, there were significant differences between the ischemic and non-ischemic LV. +p<0.05, and ++p<0.0001. N=6 per group in three independent mice.