for the production of chemicals, represent an important pillar in the building of
catalysis.
2 Within the area of biotechnology, biocatalysis has been coined as White
Biotechnology
3 and more than 300 industrial-scale processes are documented
worldwide [6].
1.2 Common Prejudices Against Enzymes
If one uses enzymes for the transformation of nonnatural organic compounds, the
following prejudices are frequently encountered: [7]
• ‘Enzymes are sensitive’.
This is certainly true for most enzymes if one thinks of boiling them in water,
but that also holds for most organic reagents, e.g., butyl lithium. When certain
precautions are met, enzymes can be remarkably stable.
4 Some candidates can
even tolerate hostile environments such as temperatures greater than 100
C and
pressures beyond several hundred bars [8–10].
• ‘Enzymes are expensive’.
Some are, but others can be very cheap if they are produced on large scale
[11]. In bulk, prices of enzymes range from ~100,000 $ per kg for a diagnostic
enzyme to ~100 $ for crude preparations, which are adequate for most chemical
reactions. Due to the rapid advances in molecular biology, costs for enzyme
production are constantly dropping and proteins can be reused if they are
immobilized.
• ‘Enzymes are only active on their natural substrates’.
This statement is certainly true for enzymes derived from the primary metabolism, which provides energy for the maintenance of life. However, it is definitely false for proteins involved in secondary metabolism, which ensures
detoxification of xenobiotics, defence against offenders and adaption to a constantly changing environment. Much of the early research on biotransformations
was impeded by a tacitly accepted dogma of traditional biochemistry which
stated that ‘enzymes are nature’s own catalysts developed during evolution to
enable metabolic pathways’. This narrow definition implied that man-made
organic compounds could not be regarded as substrates. Once this scholastic
problem was surmounted [12], it turned out that the fact that nature has developed its own peculiar catalysts over 3.9 Â 10
9 years does not necessarily imply
that they are designed to work only on their natural target molecules. Research
during the past decades has shown that the substrate tolerance of many enzymes
2 Other sectors of catalysis are heterogeneous, homogeneous and organo-catalysis.
3 Other sectors of biotechnology have been defined as ‘Red’ (medical biotechnology), ‘Green’
(agricultural biotechnology), ‘Blue’ (marine biotechnology), and ‘Grey’ (environmental
biotechnology).
4 Basic rules for the handling of enzymes are described in Chap. 5.
2
1 Introduction and Background Information
catalysis.
2 Within the area of biotechnology, biocatalysis has been coined as White
Biotechnology
3 and more than 300 industrial-scale processes are documented
worldwide [6].
1.2 Common Prejudices Against Enzymes
If one uses enzymes for the transformation of nonnatural organic compounds, the
following prejudices are frequently encountered: [7]
• ‘Enzymes are sensitive’.
This is certainly true for most enzymes if one thinks of boiling them in water,
but that also holds for most organic reagents, e.g., butyl lithium. When certain
precautions are met, enzymes can be remarkably stable.
4 Some candidates can
even tolerate hostile environments such as temperatures greater than 100
C and
pressures beyond several hundred bars [8–10].
• ‘Enzymes are expensive’.
Some are, but others can be very cheap if they are produced on large scale
[11]. In bulk, prices of enzymes range from ~100,000 $ per kg for a diagnostic
enzyme to ~100 $ for crude preparations, which are adequate for most chemical
reactions. Due to the rapid advances in molecular biology, costs for enzyme
production are constantly dropping and proteins can be reused if they are
immobilized.
• ‘Enzymes are only active on their natural substrates’.
This statement is certainly true for enzymes derived from the primary metabolism, which provides energy for the maintenance of life. However, it is definitely false for proteins involved in secondary metabolism, which ensures
detoxification of xenobiotics, defence against offenders and adaption to a constantly changing environment. Much of the early research on biotransformations
was impeded by a tacitly accepted dogma of traditional biochemistry which
stated that ‘enzymes are nature’s own catalysts developed during evolution to
enable metabolic pathways’. This narrow definition implied that man-made
organic compounds could not be regarded as substrates. Once this scholastic
problem was surmounted [12], it turned out that the fact that nature has developed its own peculiar catalysts over 3.9 Â 10
9 years does not necessarily imply
that they are designed to work only on their natural target molecules. Research
during the past decades has shown that the substrate tolerance of many enzymes
2 Other sectors of catalysis are heterogeneous, homogeneous and organo-catalysis.
3 Other sectors of biotechnology have been defined as ‘Red’ (medical biotechnology), ‘Green’
(agricultural biotechnology), ‘Blue’ (marine biotechnology), and ‘Grey’ (environmental
biotechnology).
4 Basic rules for the handling of enzymes are described in Chap. 5.
2
1 Introduction and Background Information