Identification of arsenite-and arsenic diglutathione-binding proteins in human hepatocarcinoma cells

Journal Article · Fri Jan 15 00:00:00 EST 2010 · Toxicology and Applied Pharmacology

DOI:https://doi.org/10.1016/j.taap.2009.10.013· OSTI ID:21344832

Mizumura, Ayano; Watanabe, Takayuki ^[1]; Kobayashi, Yayoi ^[1]; Hirano, Seishiro ^[1]

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1. Graduate School of Pharmaceutical Sciences, Chiba University, Yayoi, Inage, Chiba 263-8522 (Japan)

It is generally accepted that trivalent arsenicals are more toxic than the corresponding pentavalent arsenicals, since trivalent arsenicals bind the thiol groups of biomolecules, leading to a deterioration in cellular functions. In the present study, we prepared three different arsenic-bound sepharoses and investigated the binding of hepatic cytosolic proteins to pentavalent, trivalent, and glutathione-conjugated trivalent arsenicals. SDS-PAGE showed no proteins bound to pentavalent arsenic specifically. In contrast, we found a number of proteins that have specific and high affinity for trivalent arsenic. Two of those proteins were identified: protein disulfide isomerase-related protein 5 (PDSIRP5) and peroxiredoxin 1/enhancer protein (PRX1/EP). These proteins have vicinal cysteines, as previously reported. In contrast, one of the prominent proteins that did not bind to trivalent arsenic was identified as calreticulin precursor. Although there are 3 cysteines in calreticulin precursor, two of the cysteines are spaced more than 25 amino acids apart. Five synthetic peptides containing 2 vicinal cysteines were prepared to study whether they would inhibit the binding of PDSIRP5, PRX1/EP, and other arsenic-binding proteins to trivalent arsenicals. Only two of the five peptides effectively inhibited binding, suggesting that other amino acids besides the 2 vicinal cysteines may modulate the affinity of cysteine-rich proteins for trivalent arsenicals. We further investigated hepatic cytosolic proteins that bound specifically to glutathione-conjugated trivalent arsenic, which is the most abundant form of arsenical in bile fluid. Four proteins that bound specifically to glutathione-conjugated trivalent arsenic were identified; interestingly, these proteins were different from the trivalent arsenic-binding proteins. These results suggest that although glutathione-conjugation is an important process in the metabolism, excretion, and detoxification of arsenicals, glutathione-conjugated arsenicals can still react with some proteins in hepatic cells.

• OSTI ID: 21344832
• Journal Information: Toxicology and Applied Pharmacology, Vol. 242, Issue 2; Other Information: DOI: 10.1016/j.taap.2009.10.013; PII: S0041-008X(09)00451-7; Copyright (c) 2009 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0041-008X
• Country of Publication: United States
• Language: English

Related Subjects

60 APPLIED LIFE SCIENCES
ARSENIC
BILE
CYSTEINE
DETOXIFICATION
GLUTATHIONE
HEPATOMAS
LIVER
MEN
METABOLISM
TOXICITY
AMINO ACIDS
ANIMALS
BIOLOGICAL MATERIALS
BODY
BODY FLUIDS
CARBOXYLIC ACIDS
CARCINOMAS
DIGESTIVE SYSTEM
DISEASES
DRUGS
ELEMENTS
GLANDS
MALES
MAMMALS
MAN
MATERIALS
NEOPLASMS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
ORGANS
PEPTIDES
POLYPEPTIDES
PRIMATES
PROTEINS
RADIOPROTECTIVE SUBSTANCES
RESPONSE MODIFYING FACTORS
SEMIMETALS
THIOLS
VERTEBRATES