FIG 1.

HNP-1 can be effectively produced in E. coli expressing preproHNP-1 after IPTG induction. (A) The sequence of preproHNP-1 tagged with six histidine residues, which was cloned into the pET-28a(+) vector. (B) Growth curves of E. coli strain XPX-1 containing pET-28a(+)-preproHNP-1 with (+IPTG) or without (−IPTG) 1 mM IPTG induction. Asterisks represent significant differences from the −IPTG group. (C) High-resolution Tris-Tricine gel analysis for the total cell lysates prepared from E. coli strain XPX-1 with (+IPTG) or without (−IPTG) 1 mM IPTG induction. PreproHNP-1 and HNP-1 are displayed as indicated. (D) Representative MS₂ spectrum of peptide ADEVAAAPEQIAADIPEVVVSLAWDESLAPK from preproHNP-1. (E) Representative MS₂ spectrum of peptide YGTCIYQGR from HNP-1. Data were analyzed using a two-tailed Student's t test and plotted as the mean ± SD for each condition. **, P < 0.01.