Crithidia

The D-arabino-D-galactan of cells of the insect protozoon Crithidia fasciculata contains /3-D-(l—>3)-linked D-galactopyranosyl main-chain units, some of which are unsubstituted others are substituted at 0-2 by (single-unit) D-arabinopyranosyl groups. The 13C-n.m.r. spectrum shows that these are only partial structures, as the C-l region contained 8 signals.125... 

N-Ribohydrolases have been found to be involved in novel pathways of purine salvage in protozoan parasites as well as in nucleic acid repair, and exhibit other interesting biological activities [178]. In order to investigate the molecular electrostatic potential surface of the enzyme from the trypanosome Crithidia fasci-culata, several l,4-dideoxy-l,4-imino-D-ribitol derivatives were synthesized as nucleoside analogues and their inhibitory powers were tested [179,180]. In the course of this work, l,4-dideoxy-l,4-imino-l(S)-phenyl-D-ribitol (97) was found to inhibit this enzyme with K 30 nmol/1. 

Hard FU, Hlodan R, Langer T (1994) Molecular chaperones in protein folding the art of avoiding sticky situations. Trends Biochem Sci 19 20-25 Hausler T, Stierhof YD, Blattner J, Clayton C (1997) Conservation of mitochondrial targeting sequence function in mitochondrial and hydrogenosomal proteins from the early-branching eukaryotes Crithidia, Trypanosoma and Trichomonas. Eur J Cell Biol 73 240-251... 

Figure 5-16 (A) Electron micrograph of the network of catenated DNA circles in the mitochondrion of the trypanosome Crithidia fasciculata. (B) and (C) The same network after treatment with a topoisomerase from bacteriophage T4 that catalyzes a decatenation to form individual covalently closed circles (Chapter 27). Five times as much enzyme was added in (C) as in (B). Two sizes of circles are present. Most are "minicircles", each containing about 2300 bp but a smaller number of larger 35-kb "maxicircles" are also present. One of these is marked by the arrow. From Marini, Miller, and Englund.183...

D6. Deng, J. S., Sontheimer, R. D., Lipscomb, M. F., and Gilliam, J. N., The binding of antihistone antibodies to Crithidia luciliae kinetoplasts is growth cycle-dependent. Arthritis Rheum. 28, 163-168 (1985). 

J4. Jonsson, J., and Norberg, R., Effect of enzyme treatment of Crithidia luciliae on the reactivity of its kinetoplast with anti-DNA sera. Scand. J. Rheumatol. 5, 221-226 (1976). 

Infection with parasites e.g., Crithidia species (23), Leishmania major (24). 

Boulanger, N., Ehret-Sabatier, L., Brun, R., Zachary, D., Bulet, P, and Imler, J.L. (2001) Immune response of Drosophila melanogasterto infection with the flagellate parasite Crithidia spp. Insect Biochem. Mol. Biol. 31,129-137. 

Horenstein BA, Parkin DW, Estupinan B, Schramm VL (1991) Transition-state analysis of nucleoside hydrolase from Crithidia fasciculate. Biochemistry 30 10788-10795... 

Olivacine Growth inhibition of Trypanosoma cruzi and Crithidia — 290... 

Nucleoside hydrolase has been proposed to participate in purine salvage in the trypanosome Crithidia fasciculata. The enzyme hydrolyses the N-glycosidic linkage of the naturally occurring purine and pyrimidine nucleosides. A geometric model of the transition state for nucleoside hydrolase for the reaction (Horenstein et al., 1991)... 

Garlic has in vitro activity against Entamoeba histolytica, Giardia lamblia, Leishmania major, Leptomonas colsoma, and Crithidia fasciculate (40,47). In vivo and clinical data is needed before garlic can be used for treatment of infections with these organisms. 

A number of protozoal parasites such as Trypanosoma, Plasmodium, Ldslinmnin, Crithidia and Toxoplasma spp. have been shown to contain at least one of the three major anti-oxidant enzymes superoxide dismutase, catalase and glutathione peroxidase [32]. Thus, many of these parasites are able to quench or scavange the oxidants... 

Biopterin (1) is one of the potent natural pteridines isolated from human urine as the growth factor of Crithidia fasciculata It has attracted much attention as a precursor of (67 )-tetrahydrobiopterin, which was known as a coenzyme of aromatic amino acid monooxygenase. ... 

Corynanthe mayumbensis (tetrahydroalstonine), 389 Crithidia fasciculata (biopterin), 375 Crotalaria agatiflora (crotanecine), 240 Crotalaria amagyroids (anacrotine), 244 Crotalaria incana shrub (anacrotine and intergerrimine), 244... 

Large hydron KIEs have been observed in enzymatic reactions at sites far removed from where chemistry is occurring. In enzymatic hydrolysis and transfer reactions of A-ribosides, it has become a common pattern to observe an inverse 4 - H KIE and a normal 5 - H KIE. These KIEs are not intrinsic to the reaction as the KIEs at these positions are negligible in the non-enzymatic reactions. Examples of such enzymatic KIEs include inosine hydrolysis by lU-NH from Crithidia fasciculata, where 4 - H KIE = 0.992, 5 - H KIE = 1.051 and NAD+ hydrolysis by diphtheria toxin A-chain (DTA), where 4 - H KIE = 0.990, 5 - H KIE = 1.032. ... 

One eleven-amino acid segment of chain, from 70 to 80, was thought for many years to be absolutely essential because it was invariant among all species then known. More recently this invariance has been broken, but in a conservative manner. Tyrosine-74 has been observed as phenylalanine in Humicola and Crithidia, and isoleucine-75 is valine in Euglena and methionine in Crithidia. (These two species also have the anomalous alanine at position 14.) Such conservative changes in a small number of distantly related eukaryotic organisms do not detract from the prediction that the left side of the molecule, residues 70-80, must have an important functional role that keeps its sequence so nearly invariant. 

In trypanosomatids, glycosphingolipids have been studied in several species of Trypanosoma, Leishmania and lower trypanosomatides,such as species of Crithidia. Since glycolipids may be important in host-parasite interactions (38), a detailed knowledge of the primary structure of these molecules isolated from trypanosomatids could provide insight into the function, biosynthesis and antigenicity of parasite carbohydrates. 

Glycosphingolipids with similar structures are found in Crithidia spp, which are considered to be lower trypanosomatids as their habitat is in invertebrate and since they do not have a cycle involving vertebrates (39). Neutral glycosphingolipids were isolated and characterized in Crithidia luciliae, C.oncopelti and C.guilhermei (40). The major glycolipids of the three species of Crithidia detected by HPTLC chromatography contain... 

---