Hamann KJ et al. (1990) J Immunol "In vitro killing of microfilariae of Brugia pahangi and Brugia malayi by eosinophil granule proteins."

Loegering DA, McCall JW, Gleich GJ, Barker RL, Checkel JL, Hamann KJ

[J Immunol, 1990]

Eosinophil infiltration and degranulation around the tissue-invasive stages of several species of helminths have been observed. Release of eosinophil granule contents upon the worms is supported by localization of two of the major granule proteins, major basic protein (MBP) and eosinophil peroxidase (EPO), on and around species of trematodes, nematodes, and cestodes. In the case of filarial worms, MBP is deposited on degenerating microfilariae (mf) of Onchocerca volvulus. Here, we performed in vitro assays of the toxicity of four purified eosinophil granule proteins, namely, MBP, EPO, eosinophil cationic protein (ECP), and eosinophil-derived neurotoxin (EDN), for the mf of Brugia pahangi and Brugia malayi. MBP, ECP, and EDN killed these worms in a dose-related manner although relatively high concentrations of EDN were necessary. EPO, in the presence of a H2O2-generating system and a halide, was the most potent toxin on a molar basis; here, the most potent halide was I- followed by Br- and Cl-. Surprisingly, EPO in the absence of H2O2 killed mf at concentrations comparable to those required for MBP and ECP. The toxicity of EPO + H2O2 + halide was inhibited by heparin, catalase, or 1% BSA, whereas the toxicity of EPO alone was inhibited only by heparin. Heparin also inhibited killing by both MBP and ECP. Despite the homology of ECP with certain RNases, placental RNasin, an RNase inhibitor, was unable to inhibit ECP-mediated toxicity. These results indicate that all of the eosinophil granule proteins are toxic to mf and they support the hypothesis that eosinophil degranulation causes death of mf in vivo.

Verma A et al. (2016) Int J Biol Macromol "NADP(+) binding effects tryptophan accessibility, folding and stability of recombinant B. malayi G6PD."

Verma A, Siddiqi MI, Suthar MK, Chandra S, Saxena JK, Doharey PK

[Int J Biol Macromol, 2016]

Brugia malayi Glucose 6-phosphate dehydrogenase apoenzyme (BmG6PD) was expressed and purified by affinity chromatography to study the differences in kinetic properties of enzyme and the effect of the cofactor NADP(+) binding on enzyme stability. The presence of cofactor NADP(+) influenced the tertiary structure of enzyme due to significant differences in the tryptophan microenvironment. However, NADP(+) binding have no effect on secondary structure of the enzyme. Quenching with acrylamide indicated that two or more tryptophan residues became accessible upon cofactor binding. Unfolding and cross linking study of BmG6PD showed that NADP(+) stabilized the protein in presence of high concentration of urea/GdmCl. A homology model of BmG6PD constructed using human G6PD (PDB id: 2BH9) as a template indicated 34% -helix, 19% -sheet and 47% random coil conformations in the predicted model of the enzyme. In the predicted model binding of NADP(+) to BmG6PD was less tight with the structural sites (-10.96 KJ/Mol binding score) as compared with the coenzyme site (-15.47 KJ/Mol binding score).

Nicholas WL et al. (1978) Nematologica "The calorific value of C. elegans (Rhabditidae)."

Stewart AC, Nicholas WL

[Nematologica, 1978]

The calorific value of populations of Caenorhabditis elegans was measured by bomb-calorimetry. A value of 27.59 kJ per g ash-free dry weight was obtained (=6,316 calories per g). This value is high, but agrees well with calculations based on previously published analyses of lipid and glycogen reserves in Caenorhabditis sp. It is suggested that when harvested from a rich culture of bacteria Caenorhabditis has substantial lipid reserves accounting for its high calorific value.

Krishna NR et al. (2013) J Enzyme Inhib Med Chem "Physicochemical characterization of an aspin (rBm-33) from a filarial parasite Brugia malayi against the important human aspartic proteases."

Krishna NR, Gunasekaran K, Krushna NS, Rajan SS, Narayanan RB

[J Enzyme Inhib Med Chem, 2013]

The aspartic protease inhibitory efficiency of rBm-33, an aspin from a filarial parasite Brugia malayi was investigated. rBm-33 was found to be thermostable up to 90C and it forms a stable 'enzyme-product' complex with human pepsin. Aspartic protease inhibitory activity was investigated using UV spectroscopy and isothermal titration calorimetry. Our results suggest that rBm-33 inhibits the activity of important human aspartic proteases that were examined with binding constants (Kb) values between 10.23 x 10(3) and 6.52 x 10(3) M(-1). The binding reactions were enthalpy driven with Hb values between -50.99 and -46.07 kJ mol(-1). From kinetic studies, pepsin inhibition by rBm-33 was found to be linear competitive with an inhibition constant (Ki) of 2.5 (+/-0.8) nM. Because of the inhibitory efficacy of Bm-33 against important human aspartic proteases which play a vital role in immune-regulation along with other functions, Bm-33 can be projected as a drug target for the filariasis.