Purification of a toxic cysteine protease produced by pathogenic Aeromonas hydrophila isolated from rainbow trout
✍ Scribed by Ping-Chung Liu; Wen-Hsiao Chuang; Chih-Ching Tu; Kuo-Kau Lee
- Publisher
- John Wiley and Sons
- Year
- 2010
- Tongue
- English
- Weight
- 434 KB
- Volume
- 50
- Category
- Article
- ISSN
- 0233-111X
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✦ Synopsis
Abstract
An extracellular lethal toxin produced by Aeromonas hydrophila strain RT860715K originally isolated from diseased rainbow trout (Oncorhynchus mykiss) was purified by using Fast Protein Liquid Chromatography system with hydrophobic interaction chromatography and anion exchange columns. The toxin was a cysteine protease, inhibited by L ‐cysteine, iodoacetic acid, N ‐ethylamleimide, P‐chloromercuibenzene‐sulfonic acid and N‐α‐p‐tosyl‐1‐lysine‐chloromethyl ketone (TLCK), and showed maximal activity at pH 6.0. The molecular weight of the purified enzyme proved to be 94 kDa as estimated by SDS‐PAGE. In addition, the toxin was also completely inhibited by HgCl~2~ but partially inhibited by ethylenediamine tetraacetic acid (EDTA) and CuCl~2~. Both the extracellular products of Aeromonas hydrophila RT860715K and the purified protease were lethal to rainbow trout (weighing 18 g) with LD~50~ values of 2.87 and 0.93 μg protein g^–1^ fish body weight, respectively. The addition of L‐cysteine completely inhibited the lethal toxicity of the purified protease, indicating that this cysteine protease was a lethal toxin produced by the bacterium. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)