Front Matter
tina sui
(Tina Sui)
#1
Preface
In the last two decades, our understanding of biocatalysts has increased considerably,
as have the number of applications of biocatalysts for synthesis. The success of
biocatalysts stems from better availability of enzymes – mainly due to the vast pro-
gress in genetic engineering –, advances in bioreaction engineering, increasing de-
mands for environmentally-friendly processes, which makes a biocatalytic route
more attractive and often more cost-effective than a chemical one.
Most of the approximately 90 million metric tonnes of fats and oils produced
worldwide are used in human nutrition. However, not all fats and oils obtained
from animals or plants are necessarily ideal for the human diet, e.g., high contents
of saturated fatty acids can cause cardiovascular diseases. Beside physico-chemical
modifications and the introduction of genetically engineered plants producing
“designer-oils”, biocatalysts offer an alternative way to concert lipids into suitable
edible products as well as their conversion into “basic-chemicals” useful for,
e.g., synthesis of detergents or emulsifiers.
From all enzymes available in nature, hydrolases are probably most easy-to-use,
because they do not require cofactors and are usually rather stable under process
conditions. This holds especially true for lipases and phospholipases. A large num-
ber of lipases are commercially available, and several industrial processes use lip-
ases. As lipids are the natural substrates of lipases it is not surprising that most
chapters in this book review their application in lipid modification, such as hydro-
lysis to produce free fatty acids, synthesis of partial glycerides, enrichment/isolation
of polyunsaturated fatty acids which are important for the human diet. Also covered
are their cloning, expression and mutagenesis as well as attempts to understand the
molecular basis for their specificity and stereoselectivity. In addition, engineering
aspects and the choice of suitable solvent systems are addressed.
Availability and applications of phospholipases are still less developed compared
to lipases. The two chapters in this book allow the conclusion, that in the near future
drawbacks such as stability under process conditions and difficult expression in suit-
able hosts will be overcome.
Other enzymes frequently studied in lipid modification are lipoxygenases and
P450-monooxygenases, which are reviewed in the remaining chapters. They are
very attractive for organic synthesis, because they allow functionalization of fatty
acids in order to generate, e.g., flavors and emulsifiers such as sophorose lipids.
I am convinced that this book – reflecting the state-of-the-art of enzymatic lipid
modification written by leading experts in their field – will provide the reader with
guidelines how to select suitable enzymes and how to apply them efficiently.
Comments and suggestions are welcome and will be posted together with updates
