Identification and characterization of the pseudopterosin diterpene cyclase, elisabethatriene synthase, from the marine gorgonian, Pseudopterogorgia elisabethae
作者:Amber C Kohl、Russell G Kerr
DOI:10.1016/j.abb.2004.01.019
日期:2004.4
The pseudopterosins are diterpene glycosides isolated from the marine gorgonian, Pseudopterogorgia elisabethae, which exhibit anti-inflammatory and analgesic activity greater than the industry standard, indomethacin. Previously, we isolated the pseudopterosin diterpenecyclase product, elisabethatriene, using a radioactivity-guided isolation. Identification of this metabolite, and the conversion of
Purification and kinetic properties of elisabethatriene synthase from the coral Pseudopterogorgia elisabethae
作者:Thomas B. Brück、Russell G. Kerr
DOI:10.1016/j.cbpb.2005.11.016
日期:2006.3
The Bahamian octocoral Pseudopterogorgia elisabethae is the source of pseudopterosins, diterpene glycosides with potent anti-inflammatory activity. The first committed step in pseudopterosin biosynthesis comprises the cyclisation of the universal diterpene precursor geranylgeranyl diphosphate to elisabethatriene. This reaction is catalysed by elisabethatriene synthase, which was purified to homogeneity from a crude coral extract. This represents the first purification to apparent homogeneity of a terpene cyclase from any marine source. The reaction kinetics of elisabethatriene synthase was examined using a steady state approach with H-3-labelled isoprenyldiphosphates varying in carbon chain length (C-10, C-15, C-20,). For the reaction of elisabethatriene synthase with its natural substrate geranylgeranyl diphosphate, values of K-m (2.3 x 10(-6) M), V-max (3.4 x 10(4) nM elisabethatriene*s(-1)) and the specificity constant (k(cat)/K-m =1.8 x 10(-10) M-1 *s(-1)) were comparable with diterpene cyclases from terrestrial plants. Elisabethatriene synthase also catalysed the conversion of C-15 and C-10 isoprenyldiphosphate analogues to monoterpene and sesquiterpene olefins, respectively. Kinetic parameters indicated that substrate specificity and K-m of elisabethatriene synthase decreased with decreasing isoprenoid carbon chain length. Furthermore, GC-MS analysis showed increased product diversity with decreasing isoprenoid carbon chain length. (C) 2005 Elsevier Inc. All rights reserved.
Radioactivity-Guided Isolation and Characterization of the Bicyclic Pseudopterosin Diterpene Cyclase Product from Pseudopterogorgia elisabethae
作者:Amber C. Coleman、Russell G. Kerr
DOI:10.1016/s0040-4020(00)00930-3
日期:2000.12
The intermediate representing the first committed step in the pseudopterosin biosynthetic pathway has been discovered using a radioactivity-guided isolation. This diterpene cyclase product was identified from a cell-free extract of the marine soft coral, Pseudopterogorgiaelisabethae, which was incubated with 3H-geranylgeranyl diphosphate. Structural studies of the compound have revealed an unexpected