Lanthanide complexes in multifunctional asymmetric catalysis.

Multi-enzymatic cascade reactions, i.e., the combination of several enzymatic transformations in concurrent one-pot processes, offer considerable advantages: the demand of time, costs and chemicals for product recovery may be reduced, reversible reactions can be driven to completion and the concentration of harmful or unstable compounds can be kept to a minimum. This review summarizes the developments in multi-enzymatic cascades employed for the asymmetric synthesis of chiral alcohols, amines and amino acids, as well as for CC bond formation. In addition, a general classification of biocatalytic cascade systems is provided and bioprocess engineering aspects associated with the topic are discussed.

Multi-Enzymatic Cascade Reactions: Overview and Perspectives

Recent Advances in the Chemoenzymatic Synthesis of Carbohydrates and Carbohydrate Mimetics.

Lipases are endowed with a substrate specificity that surpasses that of any other known enzyme. This confers on these enzymes an application potential that is literally boundless. Lipases can be employed in the production of pharmaceuticals, cosmetics, leather, detergents, foods, perfumery, medical diagnostics, and other organic synthetic materials. This review attempts to present a comprehensive discussion on the present status of this unique group of enzymes in industry, as well as the actual potential. It represents an endeavor to provide a sincere answer to the question, “What can be done with this enzyme?” as well as, “Can lipase be utilized for this purpose?” It is intended that the manuscript will cover or at least mention all known applications, based on the exploitation of a particular type of reaction catalyzed by lipases. An attempt will be made to cover as large a number of references as possible, so as to further underline the importance and significance of lipase action for industry.

Applications of lipase

Enzyme-catalyzed synthesis of carbohydrates

Abst6ct : p-Fructosc-1,6-b isphosphate a ldo lase f rom rabbi t musc le (RA\ tA, EC 4.1.2 l3) is a synthet ica l ly uscfu lcata lys t for the stcreoselective aldolcbndensation between dihydroxyacetone phosphate (DHAP, l) and aldehl 'des having a rangc of structurcs. This paper dcmonstratcs that more than 50 aldehydcs [in addition to its natural substratc, >glyccraldehyde 3-phcPFtc' G-3-P (2) l arc iu6st ra tes for RAMA. Unhindered a l iphat ic , a-heteroarom-subst r tu ted, an d i f ie rent ia l ly protectcd.a lkory and amino aldehydes are substi tutes;sterical ly hindercd al iphatic and a,6-unsaturated aldehydes are not. Aromatic aldehydcs are either poot "t substrates or they do not react. Phosphorylated aldehydcs react more rapidly than thcir unphosphorylated counterparts, and aldehydes substi tuted in the a posit ion with an electroncgative group react more rapidl l ' than unsubsti tutcd al iphatic aldehydes. Pcrmissible variat ions in t t ie structure of the DHAP moiety' are much more restr icted; only two-I,3' d ihydroxy-2-butanone 3-phosphate (68) and 1,4-d ihydroxy-3-butanonel -phosphonate (69)-o f I I DHAP analogues tcs tcd weic substrates for RA\{A. neVn is stable under tire reattion conditions used in synthetic applications: it withstands organic cosolvents (up to 207o D\1SO or EIOH); i t can be uscd in immobil ized iorm, in soluble form, or enclosed within a mcmbranc; i t is a lso a i r -s tab le . Synthcscs of 5 ,6-d ideoxy-Dthreo-2-hexulose l -phosphate (82) ,5-O-methy l -Df ructose (85) , o-xy lu lcc (8t), and peracetylatedvglycero-o-altru2-octulose (91) on scales of 4 mmol-l moldemonstrate practical appl icat iongf thit catalyt ic synthetic methodoiogy. In a l imited srudy of kinetic diastereoselectivi ty, RAMA exhibits useiul select ivi ty in tyo cascsl * i t i r (*)-glyccraldchydc 3-phosphate [2; 20: ' l rat io, the major isomer being >fructose 1,6-bisphosphate (3)] andwilh (+)-2-(benzyloxyipropanal [19; 3:t rai io, t i r i major isomer being (S,S,R)-5-(benzyloxy)-3,4-dihydroxy' l-(phosphon*xl) ' h.*"n-i-on. igtlj 'When 1+j-f -hydroxybuunal (lm) reacs with DHRP, high thermodynamic diasterecelectivity was sbccnrcd: the ratio of the two stcrcoisomers (ror to lo{) is 97:3 and the major isomer is 5,?-didcoxy-t-gluco2-heptulopyrance l'phcpbatc (103) .

Mj Kim

Papers

Rabbit muscle aldolase as a catalyst in organic synthesis

Enzymes in organic synthesis

Enzymes in organic synthesis

Enzymes in Organic Synthesis