1. CARBOHYDRATE AND ENERGY
METABOLISM IN TRYPANOSOME AND
PLASMODIA
BY
ASARE, KUMI KWAME

2. TRYPANOSOMES
Trypanosomes go through a complex life cycle
involving vertebrate host and a vector tsetse
fly.
Vertebrate host comprising long slender,
intermediate and short stumpy form.
Vector phase comprising procyclic
trypomastigote, epimestigote and metacyclic
form.

3. T. brucei actively catabolize glucose, fructose,
mannose and glycerol.
Long slender form lack mitochondral TCA and
functional respiratory chain.
Short stumpy stages is able to utilize alpha
ketoglutarate, glucose, fructose and glycerol.
Blood stream form do not store energy
reserves.

4. AEROBIC CONDITION
The long slender forms metabolize glucose to
pyruvate with trace amount CO2 and sometimes
glycerol.
Lack lactate dehydrogenase, pyruvate
decarboxylase.
Short stumpy form contain mitochondra and
produce pyruvate, glycerol, acetate, succinate
and co2 .
Reoxidation of NADH in the glycosome is
mediated G3P-DHAP.

5. NAD-linked glycerol-3-phosphate
dehydrogenase and mitochondrial FAD-linked
glycerol-3-phosphate dehydrogenase-oxidase
complex.
The terminal oxidase reduce molecular oxygen
to water

6. ANAEROBIC CONDITION
Mitochondrial glycerol-3-phosphate oxidase is
inhibited with salicyl hydroxamic acid (SHAM).
Long slender forms continue to utilize glucose by
G3P-DHAP which prevent glycerol-3-phosphate.
Glycosomal ATP is trapped by the
phosphorylation of glucose.
Anaerobiosis leads to high glycerol-3-phosphate
and ADP with decrease ATP cause glycerol-3-
phosphate to diffuse out.

7. Causing reversal of glycerol kinase action to form
ATP from glycerol-3-phosphate and ADP.
In anaerobic condition glucose form equimolar
amounts of pyruvate and glycerol with a net ATP
of 1.
Cells survive and remain motile under anaerobic
condition with decrease ATP.
Glycerol can not serve as substrate because G3P
can not be oxidized to DHAP without molecular
oxygen.

8. VECTOR STAGE
Procyclic form metabolize glucose, fructose,
mannose and glycerol to produce acetate,
succinate, alanine, alpha ketoglutarate and CO2.
Under anaerobic condition utilize glucose and
glycerol and produce CO2 in a form of succinate
and acetate.
Glycosomal phosphoenolpyruvate carboxykinase
and malate dehydrogenase is present in procyclic
forms.

9. DIAGRAM

10. THE PLASMODIA
Erythrocytic stages of the malaria parasite do not
reserve carbohydrates.
Utilization of glucose increase to about 50-100
folds.
In infected red cells with P. falciparum utilize
glucose in anaerobic glycolysis to lactic acid.
Both the parasite and the host lack TCA cycle.
However, Avian malaria parasite under TCA cycle
with the presence of enzymes isocitrate
dehydrogenase and succinate dehydrogenase.

11. There is the presence malate dehydrogenase
in both mammalian parasite and avian
parasite but appears to cytosolic.
Although intraerythrocytic stages depend
mainly on glycolysis but mitochondria function
influence the parasite survival.
They are capable of oxidizing NADH, glycerol-
3-phosphate and succinate.

12. Mitochondria of P. falciparum oxidize
glutamate.
NADH-fumarate reductase involved in the
reoxidation of mitochondrial NADH.
P. falciparum has a complete set of glycolytic
enzyme which is high in the infected cells.

13. Several non-glycolytic enzymes such as
glucose-6-phosphate dehydrogenase,
diphosphoglycerate mutase and adenylate
kinase decreased in activity.
Most of the enzymes except for glucose-6-
phosphate dehydrogenase can be obtain from
the parasite after lysis.
The pathway for the synthesis of 2,3-
diphosphoglycerate is absent.