22149-65-1Relevant articles and documents
Mutated variants of squalene-hopene cyclase: Enzymatic syntheses of triterpenes bearing oxygen-bridged monocycles and a new 6,6,6,6,6-fusded pentacyclic scaffold, named neogammacerane, from 2,3-oxidosqualene
Fukuda, Yoriyuki,Watanabe, Takashi,Hoshino, Tsutomu
supporting information, p. 6987 - 7000 (2018/10/02)
Squalene-hopene cyclase (SHC) catalyzes the conversion of acyclic squalene molecule into a 6,6,6,6,5-fused pentacyclic hopene and hopanol. SHC is also able to convert (3S)-2,3-oxidosqualene into 3β-hydroxyhopene and 3β-hydroxyhopanol and can generate 3α-hydroxyhopene and 3α-hydroxyhopanol from (3R)-2,3-oxidosqualene. Functional analyses of active site residues toward the squalene cyclization reaction have been extensively reported, but investigations of the cyclization reactions of (3R,S)-oxidosqualene by SHC have rarely been reported. The cyclization reactions of oxidosqualene with W169X, G600F/F601G and F601G/P602F were examined. The variants of the W169L generated new triterpene skeletons possessing a 7-oxabicyclo[2.2.1]heptane moiety (oxygen-bridged monocycle) with (1S,2S,4R)- and (1R,2S,4S)-stereochemistry, which were produced from (3R)- and (3S)-oxidosqualenes, respectively. The F601G/P602F double mutant also furnished a novel triterpene, named neogammacer-21(22)-en-3β-ol, consisting of a 6,6,6,6,6-fused pentacyclic system, in which Me-29 at C-22 of the gammacerane skeleton migrated to C-21. We propose to name this novel scaffold neogammacerane. The formation mechanisms of the enzymatic products from 2,3-oxidosqualene are discussed.
Kinetic studies on the function of all the conserved tryptophans involved inside and outside the QW motifs of squalene-hopene cyclase: Stabilizing effect of the protein structure against thermal denaturation
Sato, Tsutomu,Hoshino, Tsutomu
, p. 1171 - 1180 (2007/10/03)
Site-directed mutagenesis experiments were carried out to identify the responsibility of the eight QW motifs for the reaction catalyzed by squalene-hopene cyclase (SHC). Alterations of the conserved tryptophans, which are responsible for the stacking structure with glutamine, into aliphatic amino acids gave a significantly lower temperature for the catalytic optimum as for the mutageneses of QW motifs 4, 5a and 5b, which are specifically present in SHCs. However, there was no change in the optimal temperatures of the mutated SHCs targeted at the other five motifs 1, 2, 3, 5c and 6. Thus, reinforcement against heat denaturation can be proposed as a function of the three QW motifs 4, 5a and 5b, but no function could be identified for the QW motifs 1, 2, 3, 5c and 6, although they are commonly found in all the families of prokaryotic SHCs and eukaryotic oxidosqualene cyclases. On the other hand, the three conserved tryptophans of W169, W312 and W489, which are located inside the putative central cavity and outside the QW motifs, were identified as components of the active sites, but also had a function against thermal denaturation. The other two tryptophan residues of W142 and W558, which are located outside the QW motifs, were found not to be active sites, but also had a role for stabilizing the protein structure. It is noteworthy that the mutants replaced by phenylalanine had higher temperatures for the catalytic optimum than those replaced by aliphatic amino acids. The catalytic optimal pH values for all the mutants remained unchanged with an identical value of 6.0.
Synthesis and enzymatic cyclization of (3S)11-fluoro-2,3-oxidosqualene
Robustell, Brian,Ikuro, Abe,Prestwich, Glenn D.
, p. 957 - 960 (2007/10/03)
A convergent asymmetric synthesis provided (3S)11-fluoro-2,3- oxidosqualene (11-FOS, 14), which was cyclized by bacterial squalene:hopane cyclase to a bridged ether. 11-FOS was neither a substrate nor an inhibitor for vertebrate oxidosqualene:lanosterol c
