[Screening and identification of CD13-binding peptides with phage display peptide library].
OBJECTIVE
To screen and identify the peptides that specifically bind to CD13 on monocytes.


METHODS
The phages capable of specific binding to CD13 were screened in the phage-displayed 12-peptide library. The affinity of the selected phages with CD13 was verified with enzyme-linked immunosorbent assay (ELISA). The sequences of the peptides bound to the phages were deduced according to the phage DNA sequences, and the functional peptides aligned using the BLASTP on the Website NCBI were synthesized. To analyze the biological function of the screened peptides, the location of the peptides bound to THP-1 cells was detected using immunofluorescence assay. The blocking effect of WM15 on the peptide binding to THP-1 cells was assessed by immunofluorescence assay.


RESULTS
The phages that specifically bound to CD13 were effectively enriched to approach saturation after 4 rounds of panning. The recovery rate in the fourth round was 30 times that in the first round. Twenty selected phages were verified by ELISA, and the signals of 10 phages were higher than the control. The sequences of the peptides P9 and P7 showed 83% and 100% identity with those of human cytomegalovirus (HCMV) UL38 and UL105, respectively. The peptides bound to the cell membrane of THP-1 cells as shown by immunofluorescence assay. The binding of the peptides P9 and P7 to THP-1 cells was blocked by CD13-specific monoclonal antibody WM15 at different levels.


CONCLUSIONS
Two peptides (P7 and P9) that can specifically bind to CD13 have been screened successfully, and these two peptides show specific binding to CD13 on the membrane of THP-1 cells.
Zhang
Yong
Y
Department of Thoracic Surgery, First Affiliated Hospital of Xi'an Jiaotong University College of Medicine, Xi'an 710061, China. zhangyongyang05@163.com
Lü
Yi
Y
Zhang
Xu-feng
XF
Yu
Liang
L
Liu
Chang
C
Zhang
Ni
N
Wang
Hao-hua
HH
Wan
Zhen
Z
Xie
Zhan-tao
ZT
Hu
Liang-shuo
LS
Zhan
Han-xiang
HX
D000595:Amino Acid Sequence; D001667:Binding, Competitive; D018826:CD13 Antigens / Q000032:analysis / Q000378:metabolism*; D002460:Cell Line; D006801:Humans; D008969:Molecular Sequence Data; D019151:Peptide Library; D010455:Peptides / Q000378:metabolism; D011485:Protein Binding
D019151:Peptide Library; D010455:Peptides; D018826:CD13 Antigens