F7H/K/R、F51A/I/L/V/Y、T143A/G/S/V、A150G/V、N200H/K/Q/R、I202G/L/V、S224C/F/H/I/L/P/Y、L227D/E/K/R、V228P、P229H/K/R、V230H/K/L/R、I255A/G/N/P/S/T/V/Y、P256A/K/N/Q/R/S/T/W、A257F/H/I/L/V/Y、L259F/Y、和W260D/E/F/H/I/L/N/Q/S/T/Y,或选自以下的取代使用SEQ ID NO2用于位置编号的H198A/D/E/F/G/I/L/N/Q/S/T/V/Y、F7H/K/R、F51A/I/L/V/Y、T143A/G/S/V、A150G/V、N200H/K/Q/R、I202G/L/V、S224C/F/H/I/L/P/Y、L227D/E/K/R、V228P、P229H/K/R、V230H/K/L/R、I255A/G/N/P/S/T/V/Y、T256A/K/N/Q/R/S/P/W、A257F/H/I/L/V/Y、L259F/Y、和W260D/E/F/H/I/L/N/Q/S/T/Y。