Enzymes Bradyzoite Tachyzoite
UDP-glucose phosphorylase
Starch (glycogen) synthase
Branching enzyme 1
Branching enzyme 2
D-enzyme (α-1,4-glucanotransferase)
α-glucan 0
α-amylase 0
α-glucosidase 0
R1 protein
(α-glucan water dikinase)
Debranching enzyme
↑↑: Markedly increased gene expression; ↑: Increased expression; ↑: Weak expression; 0: No gene present; T. gondii enzymes were identified at the genome Web site: htttp://www.toxodb.org. The parasite genome encodes two fructose 1,6-biphosphatase isoenzymes, a single pyruvate-carboxylase, and two PEP-carboxykinases. The conversion from glucose-6-phosphate into glucose-1-phosphate,which forms the link between amylopectin metabolism and gluconeogenesis, is catalysed by two isoforms of glucosephosphate-mutase [365]. The following soluble tachyzoite antigenic proteins have been identified: a putative protein disulfide isomerase, Hsp60, Hsp70, a pyruvate kinase, a putative glutamate dehydrogenase, a coronin, a protein kinase C receptor 1, a malate dehydrogenase, a major surface antigen 1, an uridine phosphorylase, and a peroxiredoxin [93]
Table 21: Bradyzoite and tachyzoite stage-specifically expressed genes coding the enzymes involved in T. gondii amylopectin metabolism (Coppin et al. [386]; with own modification).