The codons for the 84~(th) and 122~(th) amino acids of hFL were changed to those for E and R, and N terminal codons were changed to the optimal ones for Pichia pastoris to elevate the expression level and to increase the biological activity.

• hFL第84位和122位氨基酸的密码子分别改造为E和R的密码子，并在N端采用甲醇酵母偏爱密码子，以提高hFL的活性和表达量。