Propane-1,3-diols enzymatic

LB-ADH was used for the synthesis of vic-diols. Starting from benzaldehyde and acetaldehyde, (lS,2S)-l-phenylpropane-l,2-diol (de = 98%) and (lS,2R)-l-phenyl-propane-l,2-diol (de = 99%), respectively, could be produced in a stereoselective two-step enzymatic synthesis using benzaldehyde lyase (BAL) and accordingly benzoylformate decarboxylase (BFD) as well as LB-ADH [8] (Scheme 2.2.4.3). 

This whole-cell biotransformation is still a subject of research for several reasons Besides fhe desired product (1 )-PAC, several by-products are formed through enzymatic reduction of fhe product or fhe substrate benzaldehyde, resulting in the formation of l-phenylpropan-2,3-diol and benzylalcohol, respectively. Further byproducts are acetoin, butane-2,3-dione, l-phenyl-propane-2,3-dione, benzoic acid and 2-hydroxypropiophenone, leading to a reduced yield of the desired product and difficult product isolation. To circumvent fhis problem strain improvement and reaction engineering have been used [15, 16]. Application of an isolated enzyme in a two-phase system resulted in improved space-time yield and high product purity [17]. 

The enzymatic reactions in which adenosylcobalamin was known to serve as coenzyme by 1964 were those of glutamate mutase, methylmalonyl-CoA mutase (MCM), " propane-1,2-diol hydro-lyase (dioldehydrase, DDH), and glycerol hydro-lyase (glycerol dehydrase), shown in Equations (1)—(4). 

As an alternative to wet oxidation of organics, low temperature ashing in an oxygen plasma is possible, the ash can be dissolved in nitric acid (Waidmann et al., 1984). For subsequent determination by AAS, enzymatic solubilisation of tissues in alkaline solutions is sufficient, e.g. by the proteolytic enzyme subtilisin in the presence of trizma base (2-amino-2-hydroxymethyl propane (1,3)diol) at 55°C (Carpenter, 1981). 

Fatty acid esters of propane-1,2-diol (E477), also known as propylene glycol (11-62), and fatty acid esters of polyethylene glycol 8000 (11-63, E1521, the HLB value depends on the degree of ethoxylation) are obtained by direct esterification or by enzymatic reactions. These substances are used for oU-in-water emulsions (o/w emulsions for short). 

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