Nucleoside hydrolases from Trypanosoma cruzi

Area of Science:

• Biochemistry
• Parasitology
• Enzymology

Background:

• Nucleoside metabolism is crucial for parasitic organisms like Trypanosoma cruzi.
• Understanding enzymes involved in nucleoside breakdown can reveal potential therapeutic targets.

Purpose of the Study:

• To identify and characterize nucleoside cleaving enzymes in Trypanosoma cruzi epimastigotes.
• To investigate the substrate specificity and kinetic properties of these enzymes.

Main Methods:

• Enzyme extraction from Trypanosoma cruzi epimastigotes.
• Partial purification of nucleoside hydrolases.
• Substrate and inhibitor specificity studies.
• Determination of enzyme molecular weight using Sephadex chromatography.

Main Results:

• Four distinct nucleoside cleaving enzymes were identified: two nucleoside phosphorylases (pyrimidine-specific and purine-specific) and two nucleoside hydrolases.
• One hydrolase, inosine/guanosine hydrolase, cleaved purine nucleosides with a 9-beta-D-ribofuranosyl substituent at a common catalytic site.
• The second hydrolase was specific for 2 -deoxyinosine, accepting only purine substrates with a 6-oxo- and a 9-beta-D-2 -deoxyribofuranosyl substituent.
• Adenosine competitively inhibited inosine/guanosine hydrolase, highlighting the importance of hydroxyl groups for enzyme binding.

Conclusions:

• Trypanosoma cruzi epimastigotes possess multiple nucleoside cleaving enzymes with distinct specificities.
• The characterized nucleoside hydrolases represent potential targets for antiparasitic drug development.