We have considered the problem of protein design based on a model wher
e the contact energy between amino acid residues is fitted phenomenolo
gically using the Miyazawa-Jernigan matrix. Due to the simple form of
the contact energy function, an analytical prescription is found which
allows us to design energetically stable sequences for fixed amino ac
id residue compositions and target structures. The theoretically obtai
ned sequences are compared with real proteins, and good correspondence
is obtained. Finally, we discuss the effect of discrepancies in the p
rocedure used to fit the contact energy on our theoretical predictions
.