Fig. 5: Structures of pro-neprosin and neprosin.
From: Molecular and in vivo studies of a glutamate-class prolyl-endopeptidase for coeliac disease therapy
a Orthorhombic crystals of pro-neprosin (left panel) contained a complex of the cleaved PD (p) and the CD (e) (centre-left panel). Mature enzyme crystals were monoclinic (centre-right panel, crystal form I; right panel, crystal form II). The experiment of the centre-left panel was performed once. b The structure of pro-neprosin was solved using a lutetium derivative. At one site (left panel), the Lu3+ cation (green sphere) was nona-coordinated by two carboxylate oxygens plus five nitrogen atoms from the organic scaffold and the carboxylate oxygens of protein residue E89 at distances spanning 2.40–2.65 Å. Final (2mFobs-DFcalc)-type Fourier map of the derivative contoured at 1.3 σ (right panel). c Ribbon-type plot of pro-neprosin in frontal (left panel) and lateral (right panel) perspectives. The PD is gold with magenta helices. The mature enzyme is shown in salmon. Disordered/cleaved segments are indicated by grey dashed lines. The two glycosylation sites at N145 and N152, the seven cysteines, A60, and the two catalytic glutamates (E188 and E297) are shown for their side chains and labelled. The final Fourier map around the two glycan chains is pictured at 0.6 σ. d Topology of pro-neprosin with strands as arrows (labelled β1–β22) and the two short helices (α1 and α2) as magenta rods. The terminal residues of each secondary structure element are indicated. The PD has yellow strands and magenta helices, the front sheet of the mature enzyme moiety is in orange, and the back sheet is in brown. The seven cysteines are further indicated in green, the glycans are shown as green rhombi. The catalytic glutamates are marked for reference. e The top row shows the front view of pro-neprosin as in (c) (left) and the back view (right), both depicting the PD as yellow ribbon and the Coulombic surface of the CD (red, –10 kcal/mol·e; blue, +10 kcal/mol·e) computed with Chimera85. The calculated pI of the mature enzyme component is 4.3. The bottom row shows the same except that here the PD is shown for its Coulombic surface (pI = 9.5) and the CD as salmon ribbon.
