Structural basis for an exceptionally strong preference for asparagine residue at the S2 subsite of Stenotrophomonas maltophilia dipeptidyl peptidase 7 oleh Akihiro Nakamura, Yoshiyuki Suzuki, Yasumitsu Sakamoto, Saori Roppongi, Chisato Kushibiki, Natsuri Yonezawa, Masato Takahashi, Yosuke Shida, Hiroaki Gouda, Takamasa Nonaka, Nobutada Tanaka, Wataru Ogasawara