The oxylipin pathway generates not only prostaglandin-like jasmonates but also green leaf volatiles (GLVs), which confer characteristic aromas to fruits and vegetables. Although allene oxide synthase (AOS) and hydroperoxide lyase are atypical cytochrome P450 family members involved in the synthesis of jasmonates and GLVs, respectively, it is unknown how these enzymes rearrange their hydroperoxide substrates into different products. Here we present the crystal structures of Arabidopsis thaliana AOS, free and in complex with substrate or intermediate analogues. The structures reveal an unusual active site poised to control the reactivity of an epoxyallylic radical and its cation by means of interactions with an aromatic pi-system. Replacing the amino acid involved in these steps by a non-polar residue markedly reduces AOS activity and, unexpectedly, is both necessary and sufficient for converting AOS into a GLV biosynthetic enzyme. Furthermore, by combining our structural data with bioinformatic and biochemical analyses, we have discovered previously unknown hydroperoxide lyase in plant growth-promoting rhizobacteria, AOS in coral, and epoxyalcohol synthase in amphioxus. These results indicate that oxylipin biosynthetic genes were present in the last common ancestor of plants and animals, but were subsequently lost in all metazoan lineages except Placozoa, Cnidaria and Cephalochordata.

Structural insights into the evolutionary paths of oxylipin biosynthetic enzymes.

Molecular enzymology of lipoxygenases.

Allene Oxide Synthase-lipoxygenase Pathway in Coral Stress Response. Alleenoksiidi süntaas-lipoksügenaasi rada korallide stressivastuses

Structure of a calcium-dependent 11R-lipoxygenase suggests a mechanism for Ca2+-regulation

The N-terminal β-barrel domain of mammalian lipoxygenases including mouse 5-lipoxygenase is not essential for catalytic activity and membrane binding but exhibits regulatory functions

Identification of a functional allene oxide synthase-lipoxygenase fusion protein in the soft coral Gersemia fruticosa suggests the generality of this pathway in octocorals.

A total conformational analysis of diastereomeric esters was performed and the conformational shielding models (CSM) of the esters necessary for the NMR spectroscopic stereochemical assignment of carboxylic acids or alcohols were calculated. The esters of ( R )-2-butanol and both enantiomers of O -methylphenylacetic acid (MPA), 2-phenoxypropanoic, 2-(2-formylphenoxy)propanoic, 2-methoxy-3-phenyl-propanoic and 2-methoxy-2-methyl-3-phenylpropanoic acids were investigated. The calculation method used was DFT B3LYP/6-31+G ∗ (at the highest level in the optimization cascade). The Boltzmann weighting of individual conformers, covering an energy range of 2 kcal/mol, was used to evaluate the ring current effects of the aromatic group on the basis of a classical Pople point-dipole model describing anisotropy. The results afforded a CSM for the pairs of diastereomeric esters. The calculated CSM coincides with an empirical CSM of MPA and 2-phenoxycarboxylic acid esters and is in accordance with the experimental stereochemical results obtained for 2-methoxy-3-phenylpropanoic acid esters. The low values observed for the differential shieldings (Δ δ RS ) of 2-methoxy-2-methyl-3-phenylpropanoic acid esters were confirmed by their complex conformational equilibrium.

A total conformational analysis of diastereomeric esters and calculation of their conformational shielding models

An extension of the scope of the chemoenzymatic strategy for the synthesis of stereochemically pure pyranose deoxy sugar esters of different carboxylic acids has been achieved. The objective of the work was to extend the strategy to the synthesis of furanose deoxy sugar derivatives and additionally, to N-Boc-protected amino acid esters. With all used carboxylic acids (deoxycholic acid, α-methoxyphenylacetic acid, N-Boc- l -phenylalanine and N-Boc- l -tyrosine) the lipase-catalyzed stereoselective acetylation of furanose or pyranose hemiacetal moiety as a key step afforded one desired stereochemically pure acetylated hemiacetal deoxy sugar ester in high de.

A chemoenzymatic synthesis of deoxy sugar esters involving stereoselective acetylation of hemiacetals catalyzed by CALB

This chapter contains sections titled: Production of Isorhamnetin 3-O-Glucoside in Escherichia coli Using Engineered Glycosyltransferase Multienzymatic Preparation of (−)-3-(Oxiran-2-yl)Benzoic Acid Enzymatic Synthesis of Carbohydrates from Dihydroxyacetone and Aldehydes by a One Pot Enzyme Cascade Reaction Aldolase Based Multi-Enzyme System for Carbon[BOND]Carbon Bond Formation Tandem Biocatalytic Process for the Kinetic Resolution of β-Phenylalanine and its Analogs A Chemoenzymatic Synthesis of a Deoxy Sugar Ester of N-Boc-Protected L-Tyrosine Electrochemical Systems for the Recovery of Succinic Acid from Fermentations

Malle Kreen

Papers

Identification of a functional allene oxide synthase-lipoxygenase fusion protein in the soft coral Gersemia fruticosa suggests the generality of this pathway in octocorals.

A total conformational analysis of diastereomeric esters and calculation of their conformational shielding models

A chemoenzymatic synthesis of deoxy sugar esters involving stereoselective acetylation of hemiacetals catalyzed by CALB

Tandem and Sequential Multi-Enzymatic Syntheses