In this paper, we study the change mechanism of UV of three amino acids with positively charged R-group, which are
processed under alternating electric field. We prepared 0.01mol/L aqueous solution of lysine(K), arginine(R), histidine(H)
respectively, then disposed them at different frequency electric field for 5 minutes, scanning UV spectrum finally. As a
result, red/blue shift and hyperchromic/hypochromic effect arise in spectrums of these three amino acids. Compared with
control group, Δλ<sub>Kmax</sub> is between -0.4nm and 0.8nm, Δλ<sub>Rmax</sub> between -0.4nm and 0.8nm, Δλ<sub>Hmax</sub> between -2.2nm and
-0.6nm; Δε<sub>Kmax</sub> is between -2.657% and 2.143%, Δε<sub>Rmax</sub> between -4.997% and -1.581%, Δε<sub>Hmax</sub> between -2.098% and
0.314%. The levels of the amino acid molecules and the energy levels difference are affected by the excitation of
alternating electric field. The changes of energy level difference result in the occurrence of UV spectrum red/blue shift.
There is reduced trend of Δλ<sub>max</sub> along with increasing frequency. The number of molecules, which meet the energy levels
in the conditions of transition, is changed by the changes of molecular levels, so comes changes of
hyperchromic/hypochromic effect and the changes decrease with increasing frequency.