Effect of Organic Solvents
SYNTHETIC EXPLOITATION
OF ENZYMES:
BIOCATALYSIS IN ORGANIC
SOLVENTS: FUNDAMENTALS
ENZYMES IN ORGANIC SYNTHESIS
1. Enzymes catalyze a broad spectrum of reactions with high turnover numbers. Rate enhancements approach 1012 fold.
2. Enzymes may accept a wide range of substrates.
3. Enzymes are highly regio and stereoselective.
4. Enzyme reactions take place under mild conditions; this minimizes problems of isomerization and racemization.
5. Enzymatic processes are less hazardous and polluting than conventional chemistry-based methodologies.
Problems associated with enzyme use
1. Instability: immobilization, encapsulation, modification.
2. Cofactor requirements: regeneration of cofactor in situ.
3. Limited water solubility of many organic substrates.
Representations of some organic solvent systems
a)biphasic system b)reverse micellar system organic phase
aqueous phase
c) organic solvent system biocatalyst
Carrea, Trends in Biotechnology, 2, 102-106, 1984
Scheme of a biocatalytic biphasic system involving co-factor regeneration.
Fernandes and Cabral in “Organic Synthesis with Enzymes in Non-Aqueous
Media” Wiley-VCH, 2008, pp 191-210.
Advantages of using enzymes in water-organic solvent biphasic systems
Increased solubility of hydrophobic substrates
Smaller reaction volumes and increased volumetric productivity
Minimization of substrate/product inhibition of the biocatalyst, because of their low concentration in the aqueus phase where reaction takes place
Facilitated product recovery
Solvent requisites for application in biphasic systems
a) Biocompatible toward biocatalyst activity and/or stability
b) High capacity to dissolve substrates and/or products
c) Low cost
d) Non-biodegradable
e) Non-toxic
f) Relatively high boiling point
Solvent physical parameters that might be correlated with biocatalyst activity and/or stability
a) Log P (logarithm of partition coefficient between n-octanol and H2O)
OF ENZYMES:
BIOCATALYSIS IN ORGANIC
SOLVENTS: FUNDAMENTALS
ENZYMES IN ORGANIC SYNTHESIS
1. Enzymes catalyze a broad spectrum of reactions with high turnover numbers. Rate enhancements approach 1012 fold.
2. Enzymes may accept a wide range of substrates.
3. Enzymes are highly regio and stereoselective.
4. Enzyme reactions take place under mild conditions; this minimizes problems of isomerization and racemization.
5. Enzymatic processes are less hazardous and polluting than conventional chemistry-based methodologies.
Problems associated with enzyme use
1. Instability: immobilization, encapsulation, modification.
2. Cofactor requirements: regeneration of cofactor in situ.
3. Limited water solubility of many organic substrates.
Representations of some organic solvent systems
a)biphasic system b)reverse micellar system organic phase
aqueous phase
c) organic solvent system biocatalyst
Carrea, Trends in Biotechnology, 2, 102-106, 1984
Scheme of a biocatalytic biphasic system involving co-factor regeneration.
Fernandes and Cabral in “Organic Synthesis with Enzymes in Non-Aqueous
Media” Wiley-VCH, 2008, pp 191-210.
Advantages of using enzymes in water-organic solvent biphasic systems
Increased solubility of hydrophobic substrates
Smaller reaction volumes and increased volumetric productivity
Minimization of substrate/product inhibition of the biocatalyst, because of their low concentration in the aqueus phase where reaction takes place
Facilitated product recovery
Solvent requisites for application in biphasic systems
a) Biocompatible toward biocatalyst activity and/or stability
b) High capacity to dissolve substrates and/or products
c) Low cost
d) Non-biodegradable
e) Non-toxic
f) Relatively high boiling point
Solvent physical parameters that might be correlated with biocatalyst activity and/or stability
a) Log P (logarithm of partition coefficient between n-octanol and H2O)