Summary. Relation between Structure and Function

At the nonspecific level, the —SH group can be pictured to play an in vivo role in providing protection against ionizing rays, heavy metal and, mitotic poisons, or as in regulating the activity of metal-dependent enzymes, by its power to complex metals. 

Glutathione is known to participate, through its y-peptide linkage, in a transpeptidation reaction which may have an extraordinary interest as a mechanism for the synthesis of larger and more varied peptides and which has only begun to be investigated. The importance of glutathione in these transpeptidation reactions is difficult to evaluate until both the diversity and quantitative extent of such reactions are known. 

On the other hand, as Binkley and Nakamura have reported (68), the a-peptide bond of cysteinylglycine, which is normally sensitive to peptidases when this dipeptide is free, is in some way stabilized by its association, with the 7-peptide linkage when cysteinylglycine is part of glutathione. 

The attractive hypothesis that the GSH occupies a key position in peptide synthesis as a donor peptide or peptide bond reservoir for transpeptidation reactions has been given support by the work of Hanes et al. (252,253). 

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