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based on
'H-NMR
data (Gincel
er a / . ,
1994). The polypeptide backbone appears to be
composed of four helices linked by flexible loops with a hydrophobic cavity that may
accommodate a variety of lipids (Lerche
ct
ol., 1997).
Crystallographic studies have been carried out in order to evaluate these
models. Although wheat (Pebay-Peyroula
er
crl., 1992) and rice (Hwang
er
ol., 1993)
LTPs have been crystallized, the first crystal structure was determined in maize LTP
(Shin
et
01..
1995). The 3D solution structure of wheat ns-LTP complexed with
prostaglandin B2, a lipid with both vinyl and hydroxylated groups has been
determined by
'H
2D NMR. The global fold of the protein is close to that of
previously published structures of wheat, maize, barley and rice ns-LTPs. Structural
comparisons of free and bound wheat ns-LTP reveal that the binding of prostaglandin
B2 hardly affects the global fold of the protein (Tassin-Moindrot
er
01.. 2000).
2.4.2. Biological roles and antimicrobial activity of LTP
Based on their in
vitro
properties in lipid transfer and acyl chains binding. the
LTPs could be involved in several functions of the cell, where movement of lipids is
thought to be vital, such as in membrane biogenesis. Plant LTPs have also been
reponed to involve in cutin formation (Pyee and Kolattukudy, 1995). embryogenesis
(Sterk
et
al. 1991), defense reactions against phytopathogens (Fleming
et
al., 1992;
Molina and Garcia-Olmedo, 1993; Thoma
et
a / . , 1993; Pyee
et
a!., 1994). symbiosis
(Krause
et
al., 1994) and adaptation of plants to various environmental conditions
(Hughes
er
at., 1992; White
et
al., 1994; Thoma
et
al.. 1994).
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