Insect Biochemistry and Insect Biochemistry and Molecular Bio

rsity form ine a s an adenosine deaminase gene. A deficiency in the gene encoding the major enzyme is lethal in mouse and Drosophila and leads to severe combined deficiency (SCID) in human. In these organisms, enzyme deficiency causes increased adenosine/deoxyadenosine adenosine and 2-deoxyadenosine (referred to as deoxy-adenosine) into inosine and 20-deoxyinosine, respectively active site are retained in all organisms from Escherichia coli to human (Chang et al., 1991). Drosophila melanogaster and human, contain genes of both subfamilies (Table 1). Phylogenetic analysis of been studied for more than three decades. They are characterized by a relatively short N-terminal region and predominantly cytoplasmic localization. Proteins ARTICLE IN PRESSbelonging to this subfamily have been discovered in all organisms that have been investigated, includin