Читать книгу Plant Nucleotide Metabolism - Hiroshi Ashihara - Страница 76

Deoxyribonucleoside kinases salvage deoxyribonucleosides by transfer of a phosphate group to the 5′ position of a deoxyribonucleoside. This salvage pathway is well characterized in mammals, but little is known about deoxyribonucleoside salvage enzymes in plants.

Relatively high activity of deoxyadenosine kinase (dAK, EC 2.7.1.76) and deoxyguanosine kinase (dGK, EC 2.7.1.113) was detected in extracts of potato tubers (Katahira and Ashihara 2006) (see Table 5.1) and A. thaliana (Clausen et al. 2012). There are two types of genes that encode deoxyribonucleoside salvage enzymes in the A. thaliana genome. One is a single AtdNK gene which codes deoxynucleoside kinase (dNK, EC 2.7.1.145). The enzyme is able to use deoxyadenosine, deoxyguanosine, and deoxycytidine as substrates. Another is a thymidine kinase-like enzyme which participates in pyrimidine salvage (Clausen et al. 2012; Clausen et al. 2008) (see Part III). These findings suggest that the activity of dAK and dGK detected in plant extracts may be due to dNK which possesses broad substrate specificity.