The enormous advances made in the last ten years in the understanding of protein structure and function have been causing a quiet revolution in biology. But with the greater awareness of the multiple functions of proteins and the wide- spread technical capabilities for studying proteins, it became apparent that complete metabolic blocks are only the extreme expression of a continuum of effects

(or malfunctioning), enzyme that has become an important issue in inherited disease, and new strategies for therapy are being devised to compensate for the misbehavior of such enzymes.