Rigorous calculations were performed for spin-orbit coupling terms of the Breit-Pauli Hamiltonian in the calculation of the parity-violating energy shifts E-pv using the sum-over-state perturbation theory, and the role of one-electron and two-electron spin-orbit coupling terms was examined. Calculations on amino acids and helical n-alkanes have suggested that inclusion of one-center terms both of one-and two-electron spin couplings is sufficient to estimate the E-pv values quantitatively.