FIG. 1. The sequence and structure of the L. mexicana chitinase.

A. The deduced amino acid sequence of the L. mexicana chitinase 1 (LmexCht1) gene. The underlined sequence delineates a putative 28 aa signal peptide (Met¹ – Ser²⁸). The light gray boxes (marked: I [Leu¹²³-Ala¹³⁹] and III [Leu²⁴⁹-Gly²⁶⁴]) indicate the two putative substrate binding sites and the open box (marked: II [Arg150- Thr¹⁷⁹]) indicate the putative catalytic/active site of this enzyme. The bold-italicized residues within the open box (Leu¹⁶⁷- Glu¹⁷⁵) represent the signature sequence of the Chitinase-18 Protein Family. The two potential N-linked glycosylation sites (Asn⁴⁸ and Asn³⁸⁴) are marked with an asterisk and the single potential O-linked glycosylation site (Thr⁵²) is indicated by (τ). The dashed-underlined aa sequences (designated as Pep1-Pep4) represent regions with high levels of conservation to antigenic peptide epitopes in the L. donovani Cht1 deduced protein. B. Comparison of the conserved functional domains of the L. mexicana Cht1 (L. mex.) and L. donovani Cht1 (L.d.) chitinases. The conserved substrate binding sites (i.e. Regions I and III) and the conserved catalytic/active site (i.e. Region II) are indicated. The divergent aa residues between these two proteins are shown in bold-face.