The effect of Walterinnesia aegyptia venom proteins on TCA cycle activity and mitochondrial NAD(+)-redox state in cultured human fibroblasts.

Hazem K Ghneim,Mourad A M Aboul-Soud,Yazeed A Al-Sheikh

doi:10.1155/2015/738147

Hazem K Ghneim, Mourad A M Aboul-Soud + Show 1 more

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https://doi.org/10.1155/2015/738147

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Abstract

Fibroblast cultures were used to study the effects of crude Walterinnesia aegyptia venom and its F1–F7 protein fractions on TCA cycle enzyme activities and mitochondrial NAD-redox state. Confluent cells were incubated with 10 μg of venom proteins for 4 hours at 37°C. The activities of all studied TCA enzymes and the non-TCA mitochondrial NADP+-dependent isocitrate dehydrogenase underwent significant reductions of similar magnitude (50–60% of control activity) upon incubation of cells with the crude venom and fractions F4, F5, and F7 and 60–70% for fractions F3 and F6. In addition, the crude and fractions F3–F7 venom proteins caused a drop in mitochondrial NAD+ and NADP+ levels equivalent to around 25% of control values. Whereas the crude and fractions F4, F5, and F7 venom proteins caused similar magnitude drops in NADH and NADPH (around 55% of control levels), fractions F3 and F6 caused a more drastic drop (60–70% of control levels) of both reduced coenzymes. Results indicate that the effects of venom proteins could be directed at the mitochondrial level and/or the rates of NAD+ and NADP+ biosynthesis.

Highlights

Snake venoms are complex mixtures of protein and nonprotein components [1, 2]
Citrate synthase (CS) and Malate dehydrogenase (MDH) activities were 29.6 ± 2.33 nmoles/min/mg protein and 0.42 ± 0.03 μmoles/min/mg protein, respectively, in fibroblast cultures incubated with the crude venom, compared to 63.8 ± 5.12 nmoles/min/mg protein and 0.96 ± 0.08 μmoles/min/mg protein recorded for both enzymes, respectively, in control cultures not incubated with the crude venom (P < 0.0001)
This was true for the mitochondrial non-TCA cycle related enzyme NADP+-ICD, where the specific activity dropped from 3.38 ± 0.35 nmoles/min/mg protein in control cultures to 1.55 ± 0.14 nmoles/min/mg protein in cell cultures incubated with the crude venom

Summary

Introduction

Snake venoms are complex mixtures of protein and nonprotein components [1, 2]. Snake venom proteins are enzymes, toxins, or nerve growth factors. Snake venom toxins are proteins that can cause disruption of vital functions. Nerve growth factors are agents that cause differentiation of sympathetic or sensory neurons [4]. The nonprotein fraction of snake venoms includes sodium, potassium, phosphorus, chloride, zinc, magnesium, copper, and manganese. This fraction contains riboflavin, nucleosides, peptides, amides, lipids, and carbohydrates [5]. The clinical effects of venom proteins include neurotoxic ones causing sensory, motor, cardiac, and respiratory difficulties. The clinical manifestations of envenomation include local swelling, pain, and inflammation [8]. Renal and respiratory failure has been shown to occur leading to death [10]

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