Interaction landscape of a 'CαNN' motif with arsenate and arsenite: a potential peptide-based scavenger of arsenic.

Subhankar Sahu,Tridip Sheet,Raja Banerjee

doi:10.1039/c8ra08225a

Subhankar Sahu, Tridip Sheet + Show 1 more

Open Access

https://doi.org/10.1039/c8ra08225a

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Abstract

Arsenic (As) is a toxic metalloid that has drawn immense attention from the scientific community recently due to its fatal effects through its unwanted occurrence in ground water around the globe. The presence of an excess amount of water soluble arsenate and/or arsenite salt (permissible limit 10 μg L−1 as recommended by the WHO) in water has been correlated with several human diseases. Although arsenate (HAsO42−) is a molecular analogue of phosphate (HPO42−), phosphate is indispensable for life, while arsenic and its salts are toxic. Therefore, it is worthwhile to focus on the removal of arsenic from water. Towards this end, the design of peptide-based scaffolds for the recognition of arsenate and arsenite would add a new dimension. Utilizing the stereochemical similarity between arsenate (HAsO42−) and phosphate (HPO42−), we successfully investigated the recognition of arsenate and arsenite with a naturally occurring novel phosphate binding ‘CαNN’ motif and its related designed analogues. Using computational as well as biophysical approaches, for the first time, we report here that a designed peptide-based scaffold based on the ‘CαNN’ motif can recognize anions of arsenic in a thermodynamically favorable manner in a context-free system. This peptide-based arsenic binding agent has the potential for future development as a scavenger of arsenic anions to obtain arsenic free water.

Highlights

Arsenic (As) contamination in ground water is a global health issue.[1,2,3,4,5] It is one of the largest worldwide health disasters affecting around 150 million people who are at high risk.[6]
Because arsenic anions interfere with the metabolic pathway and normal cellular activity, priority was given to those conjugate bases of arsenic acids which exist at the physiological pH range i.e., arsenate and results related to arsenite are beyond the scope of this discussion
In comparison to HAsO42À, distributed partial charges with oxygen atoms are somewhat higher in HAsO32À due to the lower oxidation state of As (+3) enhancing the affinity of interaction

Summary

Introduction

Arsenic (As) contamination in ground water is a global health issue.[1,2,3,4,5] It is one of the largest worldwide health disasters affecting around 150 million people who are at high risk.[6]. Arsenic contamination in water has been found to be linked with numerous human diseases[20,21] which include cardio vascular abnormalities,[22,23,24,25] risk of malignancy,[3,26,27,28] diabetes,[29,30,31] gastrointestinal anomalies,[4,5] nervous system dysfunction,[32,33,34] respiratory distress and obstructive lung diseases,[35,36] dermatological lesions,[37,38] etc At this point, it is worthy to focus on aspects of arsenic removal from water. Recombinant DNA technologies have been employed to develop an arsenic-binding DNA aptamer for arsenic removal.[43]

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