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Sequence comparison revealed that the wheat lipid transfer protein is homologous to
mother maize ns-LTP whose 3D structure has been determined by 'H NMR
spectroscopy data (Gomar
el al.,
1996). Three-dimensional structure of wheat LTP
reported in this study was successfully stimulated by homology modeling tool,
molecular operating environment (MOE, version 2001.07) using maize ns-LTP as
template. The structure of wheat LTP shared 50% sequence identity with maize ns-
LTP (IAFH). The validity of the model was tested using WHATCHECK and
PROCHECK (Laskowski
et
a/.,
1993). The predicted 3D structural model of wheat
LTP is presented in Fig. 6A. The structure of wheat LTP revealed the absence of
P-
strands and presence of 6 a-helices, and 9 loop tums and the presence of 8 conserved
cysteine residues that are responsible for the formation of 4 disulphide bridges
(Cys29-77. Cys39-54, Cys55-97, Cys75-111). The active site residues Gly30. Pro5O.
Ala52 and Cys55 are responsible for catalyzing the reaction in lipid binding (Fig. 6B).
Root mean square deviation (RMSD) of query sequence structure and template
(IAFH) was found to be 0.932601
A.
The result of Ramachandran plot for wheat LTP
exhibited good stereochemistry since it has just 3.9% residues in disallowed regions.
76.3% and 19.7% in the most favoured and additionally allowed regions respectively
(Fig. 6C).
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