The ICChI is a 35-kDa, glycosylated protein isolated from the latex of the weed 
Ipomoea carnea. It displays chitinase and lysozyme activity, which could be 
important for the defense against pathogenic fungi, insects and bacteria. The 
ICChI enzyme was crystallized, and a diffraction data set was collected from a 
single crystal to 1.42 Å resolution. The crystals belong to the primitive 
tetragonal space group P43212, with unit-cell parameters a = b = 57.9, 
c = 172.0 Å, and α = β = γ = 90°. The structure was elucidated by molecular 
replacement method using a mixed model of three homologous structures from the 
N-terminal sequence of ICChI. The refined model consists of 272 amino acid 
residues and has a Rfactor of 18.93% and Rfree of 22.42%. The protein consists 
of a single globular domain with a (α/β)8 triosephosphate isomerase barrel fold. 
Three of the consensus sites for N-glycosylation viz., Asn45, Asn172, and Asn194 
containing carbohydrate moieties N-Acetylglucosamine (NAG), mannose, fucose, and 
xylose. The putative catalytic residues are Asp125, Glu127, and Tyr184. The 
crystal structure may provide fundamental information of GH18 family chitinases.