Folding of protein-like heteropolymers into unique 3D structures is in
vestigated using Monte Carlo simulations on a cubic lattice. We found
that the folding time of chains of length N scales as N-lambda at the
temperature of fastest folding. For chains with random sequences of mo
nomers lambda approximate to 6, and for chains with sequences designed
to provide a pronounced minimum of energy to their ground state confo
rmation lambda approximate to 4. Folding at low temperatures exhibits
a simple, Arrhenius-like behavior.