A polymer network structure of the matrix phase of wool fibers was modeled by polypeptide systems containing fragments of high sulfur (HS) proteins with Cys-residues oxidized in pairs to form a network. Our previous studies have shown that Cys-residues belonging to the two characteristic repeats (dipeptide and pentapeptide) from HS proteins of the matrix have a low propensity to serve as crosslinks of the matrix. This study reveals that Cys-residues located outside the two repeats have a higher propensity to serve as crosslinks of the network than Cys-residues belonging to the repeats. Effective crosslinking by the nonrepeat Cys-residues, on the one hand, and formation of intrarepeat loops by the residues of the repeats, on the other hand, can explain well-known macroscopic properties of the matrix phase, such as its elasticity and ability to swell in solvents.