ABSTRACT
The use of proteases in synthetic peptide chemistry is not confined solely to the basic step of peptide bond formation. In addition, proteases have also been described as useful and efficient agents for the introduction and removal of protecting groups. Consequently, a major part of peptide synthetic chemistry has been concerned with the development of suitable protecting groups, which are commonly subdivided into two categories: semipermanent and temporary blocking groups. Satisfactory temporary protecting groups must be selectively removable under mild conditions without injuring semipermanent blocking groups or, as a matter of course, the peptidic backbone. The deprotection step is not the only source of side reactions in synthetic peptide chemistry. Undesired by-products may also be created during the introduction of protecting groups. This problem can be overcome most efficiently, if the introduction of protecting groups is also carried out via enzyme-catalysis. Studies dealing with the enzymatic removal of side-chain protecting groups have been reported in relatively few instances.
