Protein structure of PgD5. (A) Comparison of the tertiary structure of PgD5 from Picea glauca (A) and defensin A from Nicotiana tabacum (B) by homology-based models. The α-helix and β-sheet structures are represented in pink and yellow, respectively. Models were developed using the I-TASSER website for protein structure and function predictions. (B) Secondary structure of PgD5. Secondary structure elements (α-helix and β-strands) of PgD5 are given below. Amino acid residues forming the α-core are underlined while the amino acid residues forming the γ-core are double underlined.