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BIOCHEMICAL PROCESSES AND MACROMOLECULAR STRUCTURES

Discovery and Characterization of a Novel Lachrymatory Factor Synthase in Petiveria alliacea and Its Influence on Alliinase-Mediated Formation of Biologically Active Organosulfur Compounds^1,[W],[OA]

Department of Chemistry, University at Albany, State University of New York, Albany, New York 12222

A novel lachrymatory factor synthase (LFS) was isolated and purified from the roots of the Amazonian medicinal plant Petiveria alliacea. The enzyme is a heterotetrameric glycoprotein comprised of two -subunits (68.8 kD each), one -subunit (22.5 kD), and one -subunit (11.9 kD). The two -subunits are glycosylated and connected by a disulfide bridge. The LFS has an isoelectric point of 5.2. It catalyzes the formation of a sulfine lachrymator, (Z)-phenylmethanethial S-oxide, only in the presence of P. alliacea alliinase and its natural substrate, S-benzyl-L-cysteine sulfoxide (petiveriin). Depending on its concentration relative to that of P. alliacea alliinase, the LFS sequesters, to varying degrees, the sulfenic acid intermediate formed by alliinase-mediated breakdown of petiveriin. At LFS:alliinase of 5:1, LFS sequesters all of the sulfenic acid formed by alliinase action on petiveriin, and converts it entirely to (Z)-phenylmethanethial S-oxide. However, starting at LFS:alliinase of 5:2, the LFS is unable to sequester all of the sulfenic acid produced by the alliinase, with the result that sulfenic acid that escapes the action of the LFS condenses with loss of water to form S-benzyl phenylmethanethiosulfinate (petivericin). The results show that the LFS and alliinase function in tandem, with the alliinase furnishing the sulfenic acid substrate on which the LFS acts. The results also show that the LFS modulates the formation of biologically active thiosulfinates that are downstream of the alliinase in a manner dependent upon the relative concentrations of the LFS and the alliinase. These observations suggest that manipulation of LFS-to-alliinase ratios in plants displaying this system may provide a means by which to rationally modify organosulfur small molecule profiles to obtain desired flavor and/or odor signatures, or increase the presence of desirable biologically active small molecules.

² Present address: Department of Applied Chemistry, University of South Bohemia, Braniovská 31, 370 05 eské Budjovice, Czech Republic.

The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Rabi A. Musah (musah{at}albany.edu).

^[W] The online version of this article contains Web-only data.

^[OA] Open Access articles can be viewed online without a subscription.

www.plantphysiol.org/cgi/doi/10.1104/pp.109.142539

^* Corresponding author; e-mail musah{at}albany.edu.

Received June 6, 2009; accepted August 6, 2009; published August 19, 2009.

This article has been cited by other articles:

				R. A. Musah, Q. He, R. Kubec, and A. Jadhav Studies of a Novel Cysteine Sulfoxide Lyase from Petiveria alliacea: The First Heteromeric Alliinase Plant Physiology, November 1, 2009; 151(3): 1304 - 1316. [Abstract] [Full Text] [PDF]