ated ▁am ino ▁ac ids ▁and ▁the ▁number ▁of ▁mut ations ▁The ▁value ▁ ▁represents ▁the ▁number ▁of ▁mut ations ▁that ▁occur ▁per ▁ 1 0 0 ▁am ino ▁ac ids , ▁however ▁this ▁value ▁is ▁rarely ▁accessible ▁and ▁often ▁estimated . ▁However , ▁when ▁comparing ▁two ▁prote ins ▁it ▁is ▁easy ▁to ▁calculate ▁ ▁instead , ▁which ▁is ▁the ▁number ▁of ▁mut ated ▁am ino ▁ac ids ▁per ▁ 1 0 0 ▁am ino ▁ac ids . ▁Despite ▁the ▁random ▁nature ▁of ▁mut ation , ▁these ▁values ▁can ▁be ▁approximately ▁related ▁by ▁ ▁{ | ▁class =" to cc ol ours ▁col laps ible ▁col lapsed " ▁width =" 6 0 %" ▁style =" text - align : left " ▁! Der iv ation ▁of ▁relationship ▁between ▁ ▁and ▁ ▁| - ▁| ▁Mut ations ▁in ▁the ▁primary ▁structure ▁of ▁a ▁protein ▁can ▁occur ▁anywhere ▁along ▁the ▁sequence . ▁If ▁it ▁is ▁assumed ▁the ▁distribution ▁of ▁the ▁mut ations ▁among ▁am ino ▁acid ▁positions ▁is ▁uniform , ▁the ▁problem ▁is ▁analog ous ▁to ▁a ▁distribution ▁of ▁" ball s ▁into ▁b ins ", ▁a ▁common ▁problem ▁in ▁combin ator ics . ▁In ▁a ▁case ▁where ▁ ▁balls ▁( i . e . ▁mut ations ) ▁are ▁distributed ▁amongst ▁ ▁b ins ▁( am ino ▁acid ▁positions ), ▁the ▁number ▁of ▁b ins ▁containing ▁at ▁least ▁one ▁ball , ▁ ▁has ▁a ▁distribution ▁with ▁a ▁mean ▁given ▁by ▁ ▁If ▁the ▁rate ▁of ▁mut ation ▁is ▁ ▁mut ations ▁per ▁ 1 0