Adenosine kinase and ribokinase--the RK family of proteins.

Ribokinase (RK) and adenosine kinase (AK) catalyze the phosphorylation of ribose and adenosine to ribose-5-phosphate and AMP, respectively. Belonging to the RK family of proteins, these enzymes share a number of unique structural and functional elements. Extensive work has been carried out on many aspects of these enzymes in recent years, and we summarize the wealth of information currently available on them. The topics covered include descriptions of the primary and three-dimensional structures of AK and RK, their phylogenetic relationships, biochemical aspects of these enzymes including their reaction mechanisms and ionic requirements, and also work on certain inhibitors of these enzymes. The cellular metabolism and transport of ribose and adenosine are also briefly discussed, as well as the beneficial effects of ribose and adenosine in physiology and how these effects can be harnessed for pharmacological purposes.