Ribonucleotide reductases catalyze the reduction of ribonucleotides to deoxyribonucleotides, this reaction being vitally important for all organisms. The enzyme provides a link between RNA and DNA metabolisms. Several forms of the enzyme occur in nature and those differ in their structure and catalytic mechanisms. While the direct reduction of ribonucleotides via a radical mechanism is a general mode of dNTP synthesis in all organisms, the way in which this is achieved varies. The ability of the enzyme to control DNA synthesis is of considerable clinical interest. Selective inhibition of DNA synthesis is desired, for example, in clinical applications, such as restriction of tumour growth or virus replication.

Faculty of Natural Sciences Komensky University Bratislava Czechoslovakia