A well-behaved
model chemistry previously validated for the study
of the chemical reactivity of peptides was considered for the calculation
of the molecular properties and structures of a group of five new
antifungal tripeptides, namely (2
R
)-2-[(2
S
)-2-[(2
S
)-2-amino-3-phenylpropanamido]propanamido]-5-[(diaminomethylidene)amino]pentanoic
acid, (2
S
)-2-[(2
S
)-2-[(2
S
)-2-amino-3-phenyl propanamido]propanamido]-3-(4-hydroxyphenyl)propanoic
acid, (2
S
)-2-[(2
S
)-2-[(2
S
)-2-amino-3-phenylpropanamido]-3-methylbutanamido]-3-(4-hydroxyphenyl)propanoic
acid, (2
R
)-2-[(2
S
)-2-[(2
S
)-2-amino-3-phenylpropanamido]-3-(1
H
-indol-3-yl)propanamido]-3-sulfanylpropanoic
acid, and (2
S
)-2-[(2
S
)-2-[(2
S
)-2-amino-3-phenylpropanamido]-3-(1
H
-indol-3-yl)propanamido]-3-(4-hydroxyphenyl)propanoic
acid, according to their amino acid sequences. A methodology based
on conceptual density functional theory was chosen for the determination
of the reactivity descriptors. The molecular active sites were associated
with the active regions of the molecules that were associated with
the nucleophilic, electrophilic, and radical Fukui functions. Additionally,
the p
K
a
values for the different peptides
are predicted with great accuracy, which constitutes a useful knowledge
for the process of drug design. Finally, the bioactivity scores for
the new antifungal peptides are predicted through a homology methodology
relating them with the calculated reactivity descriptors.