Purine nucleoside phosphorylase variation in the brook lamprey, Lampetra planeri (Bloch) (Petromyzone, Agnatha): evidence for a trimeric enzyme structure

Specific adenosine phosphorylase from hepatopancreas of gastropod Helix pomatia

1. Specific adenosine phosphorylase from Helix pomatia hepatopancreas was separated from inosine-guanosine phosphorylase and purified 100-165 times; molecular weights were found to be 71,000 and 90,000, respectively. 2. The enzyme is specific for deoxy- and adenosine; it is inactive for 5'-methylthioadenosine and 5-amino-4-imidazole-carboxyamide riboside. Its sensitivity to several inhibitors differs from that of eucaryotic and bacterial purine nucleoside phosphorylases, and is not identical with the sensitivity of the S. mansoni adenosine-splitting enzyme. 3. H. pomatia adenosine phosphorylase differs in its mol. wt and Km values for P(i), ribose 1P, Ado and Ade from adenosine phosphorylase of B. subtilis.

Red blood cell enzymes in the diagnosis of genetic disease

Erythrocytes are uniform cells which contain only those proteins that are synthesized during the reticulocyte stage. The relationship of red cell enzymes to gene dosage and gene expression enables the use of red cell enzyme assays to determine the presence or absence of gene defects causing enzyme deficiencies leading to various metabolic diseases; in addition, the mode of inheritance of these defects can frequently be ascertained by analyzing red cell enzymes. However, indirect evidence favoring other enzyme deficiency states can sometimes be obtained from a study of red cell enzyme activities, because apparent enzyme deficiencies may result from the accumulation of inhibitory metabolites formed due to an enzyme deficiency in other tissues. The polymorphic expression of many red cell enzymes lends itself to biochemical analysis which can produce highly accurate and specific diagnostic information.

Purine-nucleoside phosphorylase expression in Eleutherodactylus and Leptodactylus frogs

Purine-nucleoside phosphorylase expression as ascertained electrophoretically is discussed for seven species of Eleutherodactylus and one species of Leptodactylus frogs from Costa Rica. Eleutherodactylus angelicus, E. bransfordii, and E. podiciferus exhibit intraspecific variation unlike the samples of the other five species. In E. angelicus, heterozygotes form a four-banded pattern on starch gels consistent with a trimeric enzyme structure. Heterozygotes of E. bransfordii and E. podiciferus are characterized by a two-banded pattern as the heterotrimeric isozymes are apparently not expressed. Such differences in gene expression are discussed in terms of their potential phylogenetic and systematic application and significance.