Biocatalysis and Biomimetics - ACS Publications - American Chemical

Chapter 1

Biocatalysis and Biomimetics New Options for Chemistry James D. Burrington

Downloaded by 182.74.51.50 on January 3, 2016 | http://pubs.acs.org Publication Date: April 9, 1989 | doi: 10.1021/bk-1989-0392.ch001

B.P. America Research and Development, Cleveland, O H 44128 As a dominant technology in the chemicals i n d u s t r i e s , c a t a l y s i s provides an important long-term commercial target f o r biotechnology. While enzymes represent the most e f f i c i e n t c a t a l y t i c systems known, t h e i r impact on the chemicals industry r e l a t i v e to t r a d i t i o n a l c a t a l y s t s is still small. Developments at the interface of biology and c h e m i s t r y w i l l be key t o overcoming t h e major b a r r i e r s to broad i n d u s t r i a l a p p l i c a t i o n of enzyme catalysis.

The Impact of Catalysis The o v e r w h e l m i n g l y dominant t e c h n o l o g y in c h e m i c a I s - r e I a t e d industries is c a t a l y s i s . Commercial c a t a l y t i c processes account f o r over half of a l l f u e l s production and f o r 60% of the 135 MM metric tons of organic chemicals produced annually in the U.S. In f a c t 20% of the n a t i o n ' s GNP can be a t t r i b u t e d to c a t a l y t i c processes (1) . Thus, from a technical standpoint, advances in the chemicals industry are strongly linked to advances in c a t a l y s i s . A key property of c a t a l y t i c processes is s e l e c t i v i t y . Catalysis has r e v o l u t i o n i z e d process chemistry by replacement of w a s t e f u l , unselective ( i . e . multiple-product-forming) reactions with e f f i c i e n t , selective ( i . e . one-product-dominating) ones. For example, s e l e c t i v e c a t a l y t i c methanol carbonyI a t Î o n ( p r a c t i c e d by BP, BASF Monsanto, Eastman) has to a large extent substituted unselective n o n - c a t a l y t i c η-butane oxidation (Celanese, and Union Carbide processes). Control of r e a c t i v i t y by c a t a l y s i s provides the c a p a b i l i t y to s h i f t to lower cost feedstocks. In the twentieth century, advances in c a t a l y s i s have allowed the substitution of acetylene with o l e f i n s and subsequently with s y n t h e s i s gas as primary f e e d s t o c k s . For example, production of a c r y l i c a c i d , t r a d i t i o n a l l y produced by the Reppe p r o c e s s from a c e t y l e n e and CO, has now been r e p l a c e d by c a t a l y t i c oxidation of propylene. The emergence of p a r a f f i n s , the hydrocarbon feedstock of the f u t u r e , w i l l depend on development of catalysts for s e l e c t i v e alkane C-H activation (2). 0097-6156/89/0392-0001$06.00/0 ©1989 American Chemical Society

In Biocatalysis and Biomimetics; Burrington, James D., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1989.


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C a t a l y s i s has a l s o had a major impact on the f u n c t i o n a l and specialty chemicals b u s i n e s s e s , p r o v i d i n g lower c o s t routes and higher performance materials than would have otherwise been possible. Major examples are from polymer syntheses including Ζieg I e r - N a t t a , a n i o n i c , c a t i o n i c p o l y m e r i z a t i o n p r o c e s s e s , f o r f o r m a t i o n of p o l y o l e f i n s , ABS r e s i n s , polyesters and other synthetic m a t e r i a l s . F u t u r e m a t e r i a l s a r e a s i n c l u d e high t e m p e r a t u r e c o m p o s i t e s , electronic materials and conducting organics. The role of c a t a l y s i s in the petroleum industry has been equally revolutionary. Meta I-supported systems ( e . g . of Topsoe and S h e l l ) for c a t a l y t i c reforming, hydrodesulfurization and h y d r o d e n i t r i f i c a t i o n , a l k y l a t i o n c a t a l y s t s and shape s e l e c t i v e systems ( e . g . z e o l i t e s and p i l l a r e d c l a y s ) f o r c a t a l y t i c c r a c k i n g (FCC) and p r o d u c t i o n of g a s o l i n e from methanol (Mobil MTG) a l l represent s i g n i f i c a n t technical and commercial achievements. Thus, the impact of new technologies on the chemicals industries can be assessed to a large extent by i t s impact on the commercial practice of c a t a l y s i s . Nature's Catalysts At the molecular l e v e l , nature's c a t a l y s t s , the enzymes ( i s o l a t e d or as m i c r o b i a l systems) provide tremendous rate increases over the corresponding u n c a t a l y z e d r e a c t i o n s and v i r t u a l l y q u a n t i t a t i v e selectivity. The capability to both improve s e l e c t i v i t y to a s i n g l e product and u t i l i z e alternate feedstocks is well documented (3-4). A major s e l e c t i v i t y advantage of b i o l o g i c a l c a t a l y s t s over t r a d i t i o n a l systems includes the a b i l i t y to form s i n g l e products (chemical s e l e c t i v i t y ) as w e l l as s i n g l e o p t i c a l isomers (stereoselectivity). S p e c i f i c examples where b i o l o g i c a l routes are preferred commercially include fermentative processes f o r the amino acids monosodium glutamate (MSG), lysine, a s p a r t i c a c i d , c i t r i c acid and phenylalanine (5). Many other chemicals have also been produced by fermentative processes (6). Enzymes a l s o provide a p o t e n t i a l means to u t i l i z e a l t e r n a t e feedstocks which cannot be s e l e c t i v e l y a c t i v a t e d by conventional c a t a l y s t s , or to improve s e l e c t i v i t y over t r a d i t i o n a l systems. For example, the hydroxylase enzymes convert p a r a f f i n s to alcohols with v i r t u a l l y 100% s e l e c t i v i t y , a r e a c t i o n which has no analogue in t r a d i t i o n a l c a t a l y s i s (7). The N i t t o aery I o n i t r i I e to acrylamide process is an example o7 how b i o c a t a l y s i s can improve s e l e c t i v i t y over traditional c a t a l y s i s (8-10). Coaxing Nature to Work Harder The exciting technical opportunities in b i o c a t a l y s i s are tempered by the major b a r r i e r s to commercialization which s t i l l e x i s t . Most notably, these include low s t a b i l i t y of an expensive c a t a l y s t , and the high separation and c a p i t a l costs associated with low concentra t i o n s of reactants and products. These s i g n i f i c a n t b a r r i e r s are largely responsible for the lack of substantial commercial impact of enzyme and microbial c a t a l y s t s on the chemicals-related industries. High fructose corn syrup and amino


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New Options for Chemistry

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acids by fermentation remain the only s i g n i f i c a n t chemicals produced by biotechnology and represent only a t i n y f r a c t i o n of i n d u s t r i a l chemicals output.


Prospects Advances in the l i f e s c i e n c e s over the past 30 y e a r s have produced the new enabling t e c h n o l o g i e s normally a s s o c i a t e d with modern biotechnology, namely genetic e n g i n e e r i n g and monoclonal antibody methods. While these w i l l s u r e l y be key t o many new products, p a r t i c u l a r l y in health care and agricultural markets, these methods a l o n e a r e not l i k e l y t o p e r m i t a major impact on t h e chemicals industries. Along with the development of these enabling biological methods, c a t a l y s i s and other t e c h n o l o g i e s (such as computer modeling and expert s y s t e m s ) , which a l r e a d y have a major i n f l u e n c e on t h e chemicals industries, have also made major technical advances. The i n t e g r a t i o n of b i o t e c h n o l o g y with these more t r a d i t i o n a l areas represents a means to capture the technical advances across a number of chemicals-related d i s c i p l i n e s . For example, the importance of the complimentary r o l e s of surface, bulk and i n t e r f a c i a l structure in heterogeneous c a t a l y s i s ( 1 1 - 1 3 ) , a l s o i n d i c a t e s t h e need to a d d r e s s t h e s e i s s u e s in expI a i η i ng and p r e d i c t i n g c a t a l y t i c behavior of enzyme systems as wel I . From this c r o s s - d i s c i p l i n a r y approach a number of new enabling technologies are now emerging. The combination of b i o l o g i c a l and chemical c a t a l y s t s to produce h y b r i d c a t a l y s i s or "biomimetic" systems has shown some promise in capturing the high s e l e c t i v i t y of enzymes with the favorable processing c h a r a c t e r i s t i c s of t r a d i t i o n a l catalysts (see D. Clark, R. H. F i s h , R. DiCosimo c o n t r i b u t i o n s , t h i s publication). The growing body of information on s t r u c t u r e / f u n c t i o n r e l a t i o n s h i p s of enzymes i s b e i n g a c c e l e r a t e d by a d v a n c e d crystaIlographic methods and the use of computer modeling and expert systems (see G. A. Petsko, G. Klopman, W.A. Goddard c o n t r i b u t i o n s , this publication). New methods of enzymology, i n c l u d i n g novel immobilization and reaction conditions (see T . A. Hatton, N . H e r r o n , R. S i p e h i a c o n t r i b u t i o n s , t h i s publication) have demonstrated the p o t e n t i a l to improve c a t a l y t i c performance. These advances can c o l l e c t i v e l y be viewed as the growing f i e l d of b i o c a t a l y s i s and b i o m i m e t i c s . Along w i t h t h e b i o t e c h n i c a l developments, these p r o v i d e another o p t i o n f o r e x p l o i t i n g t h e p o t e n t i a l of enzyme c a t a l y s i s in the c h e m i c a l s i n d u s t r y . The f o l I owing c h a p t e r s p r e s e n t r e p r e s e n t a t i v e examples of c u r r e n t advances in t h i s emerging f i e l d .

Literature Cited 1. 2. 3. 4.

Witcoff, H. Chem. Systems Report, Third Annual Review Meeting; New York, Jan. 17-18, 1985. Weissermel, K.; Arpe, H. J., eds., Industrial Organic Chemistry, Verlag Chemie: New York, 1978, p 254. Stiefel, Ε. I. Chemical Engineering Process, Oct 21, 1987. Whitesides, G. M.; Wong, C-H. Angew. Chem. Int. Ed. Eng., 1985, 24, 617.


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5. 6. 7. 8. 9. 10. 11. 12.


13.

Sedovinikova M. S.; Belikov, V. M. Russian Chemical Reviews, 1978, 47, 357. Ouellette, R. P.; Cheremisinoff, P. Ν. Applications of Biotechnology, Technomic Publishing Co.: Lancaster, 1985, p 72. Leak, D. J.; Dalton, H. Biocatalysis. 1987, 1, 23. Nitto Chemical Industry. U.S. Patent 4 414 331, 1983. Nitto Chemical Industry. U.S. Patent 4 421 855, 1983. Nitto Chemical Industry. U.S. Patent 4 343 900, 1982. Gates, B. C.; Katzer, J. R.; Schuit, G. C. A. The Chemistry of Catalytic Processes. McGraw-Hill: New York, 1979. Grasselli, R. K.; Brazdil, J. F. Solid State Chemistry in Catalysis. ACS Symposium, Series 279, American Chemical Society: Washington, D. C., 1985. Vedrine, J. C.; Coudurier, G.; Forissier, M.; Volta, J. C. Catalysis Today, 1987, 261.

R E C E I V E D October 17, 1988


Biocatalysis and Biomimetics - ACS Publications - American Chemical

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