3.4.23.44	D75E	no maturation cleavage	
3.4.23.44	D75N	no maturation cleavage	
3.4.23.44	D75T	no maturation cleavage	
3.4.23.44	D75V	no maturation cleavage	
3.4.23.44	N363T	drastically slowed cleavage