creators_name: Dave, Sandeep
creators_name: Dkhar, H Kitdorlang
creators_name: Singh, Manvendra Pratap
creators_name: Gupta, Garima
creators_name: Chandra, Vemika
creators_name: Mahajan, Sahil
creators_name: Gupta, Pawan
type: article
datestamp: 2011-12-08 19:31:41
lastmod: 2011-12-08 19:31:41
metadata_visibility: show
title: Hexafluoroisopropanol-induced helix-sheet transition of stem bromelain: correlation to function.
ispublished: pub
subjects: QR
full_text_status: none
note: Copyright of this article belongs to Elsevier Science
abstract: Stem bromelain is a proteolytic phytoprotein with a variety of therapeutic effects. Understanding its structural properties could provide insight into the mechanisms underlying its clinical utility. Stem bromelain was evaluated for its conformational and folding properties at the pH conditions it encounters when administered orally. It exists as a partially folded intermediate at pH 2.0. The conformational changes to this intermediate state were evaluated using fluorinated alcohols known to induce changes similar to those seen in vivo. Studies using circular dichroism, fluorescence emission spectroscopy, binding of the hydrophobic dye 1-anilino-8-naphthalene sulfonic acid and mass spectrometry indicate that treatment with 10-30% hexafluoroisopropanol induces the partially folded intermediate to adopt much of the native protein's secondary structure, but only a rudimentary tertiary structure, characteristic of the molten globule state. Addition of slightly higher concentrations of hexafluoroisopropanol caused transformation from an alpha-helix to a beta-sheet and induced formation of a compact nonnative structure. This nonnative form was more inhibitory of cell survival than either the native or the partially folded intermediate forms, as measured by enhanced suppression of proliferative cues (e.g., extracellular-signal-regulated kinase) and initiation of apoptotic events. The nonnative form also showed better antitumorigenic properties, as evaluated using an induced two-stage mouse skin papilloma model. In contrast, the nonnative state showed only a fraction of the proteolytic activity of the native form. This study demonstrates that hexafluoroisopropanol can induce a conformational change in stem bromelain to a form with potentially useful therapeutic properties different from those of the native protein.
date: 2010-06
date_type: published
publication: The international journal of biochemistry & cell biology
volume: 42
number: 6
publisher: Elsevier Science
pagerange: 938-47
refereed: TRUE
issn: 1878-5875
official_url: http://www.sciencedirect.com/science/article/pii/S1357272510000610
related_url_url: http://www.sciencedirect.com/science/article/pii/S1357272510000610
related_url_type: pub
citation:   Dave, Sandeep and Dkhar, H Kitdorlang and Singh, Manvendra Pratap and Gupta, Garima and Chandra, Vemika and Mahajan, Sahil and Gupta, Pawan  (2010) Hexafluoroisopropanol-induced helix-sheet transition of stem bromelain: correlation to function.  The international journal of biochemistry & cell biology, 42 (6).  pp. 938-47.  ISSN 1878-5875