308 Chapter 9 SAQ 9.2 A medium containing bile salts such as lithocholic acid along with carbohydrates and peptone has been used to isolate gut organisms. One such isolate has been shown to completely degrade the lithocholic acid (structure given in Figure 9.1) In an experiment in which a student was examining the tolerance of this organism to Pb ions, it was observed that the organism grew quite well in 0.1 mmol I' Pb but that the lithocholic acid was only partially catabolised yielding a range of products, including the following: COOH What is the likely explanation for this observation? 9. 3. 3 Use of mutants A wide variety of mutants with modified sterol (steroid) metabolism has been produced using conventional mutagens such as N-methyl-N'-nitroso-guanidine and ultraviolet light. The organism most commonly but not exclusively used is Mycobacterium rtuitum. wild type members of this species can catabolise a range of sterols. Mutants have been produced that are blocked at various stages of the catabolism, giving rise to a wide range of products. Some of the products are used by a variety of commercial organisations as intermediates in the manufacture of medically valuable steroids. We have reported a few of the many possible examples in Table 9. 4. We would not exp abnt ights you to recall the details of these. You should, however realise that this is a very valuable commercial market and companies involved in this area hold extensive patent rights protecting these processes The strains described in Table 9. 4 are all of commercial value since they produce compounds which are either pharmacologically active or can be converted to pharmacologically important compounds. For example, the production of 14-androstadiene-3, 17-dione from p-sitosterol provides material which can be readily converted to estrone while 4-androstene-3, 17-dione can be converted to testosterone
308 Chapter 9 A medium containing bile salts such as lithocholic acid along with carbohydrates and peptone has been used to isolate gut organisms. One such isolate has been shown to completely degrade the lithocholic acid (structure given in Figure 9.1). In an experiment in which a student was examining the tolerance of this organism to Pbz+ ions, it was observed that the organism grew quite well in 0.1 mmol 1-I Pb2+ but that the lithocholic acid was only partially catabolised yielding a range of products, including the following: -I I _. . main products minor product What is the likely explanation for this observation? 9.3.3 Use of mutants A wide variety of mutants with modified sterol (steroid) meta;bolism has been produced using conventional mutagens such as N-methyl-N'-nitroscFguanidine and ultraviolet light. The organism most commonly, but not exclusively, used is Mycobacterium forhritum. Wild type members of this species can catabolise a range of sterols. Mutants have been produced that are blocked at various stages of the catabolism, giving rise to a wide range of products. Some of the produds are used by a variety of commercial organisations as intermediates in the manufacture of medically valuable steroids. We have reported a few of the many possible examples in Table 9.4. We would not expect you to recall the details of these. You should, however, realise that this is a very valuable commercial market and companies involved in this area hold extensive patent rights protecting these processes. The strains described in Table 9.4 are all of commercial value since they produce compounds which are either pharmacologically active or can be converted to pharmacologically important compounds. For example, the production of 1,4-androstadiene3,17-dione from &sitosterol provides material which can be read$ converted to estrone, while 4-androstene3,17-dione can be converted to testosterone. Pmt ah&
Biotransformation of lipids Princlple Product rium fortuitum 9a-hydroxyandrost-4-ene-4, 17 -8119 M. fortuitum 4-androstene-317-dione NRRL B11359,11045 M.向ouu RL B-8119 dinorchol-4-ene-22-oI M. fortuitum 3, 9-dihydroxy 9, 10-secoandrosta Mitsubishi FERM P-4809 5-triene-17-one Mycobacterium parafortuitum ga-hydroxyandrost-4-ene-3, 17. Mitsubishi RM P-4926 arafortuitum 4-androstene-3 17-dione Mitsubishi 3-0X0-23.24-dinorchola-1,4 Mitsubishi diene-22-ol Mycobacterium sp 1. 4-androstadiene-3 17-dione Searle 4-androstene-3 17-dione Searle RL B-3805 Rhodococcus coralinus 3 Mitsubishi FERM P-4812 arthrobacter simplex 3-hydroxy-9-0X0-9, 10-SeC Mitsubishi FERM P-4477 pregna-1, 3,5 triene- 20-carboxylic acid Corynebacterium equi 9-a-hydroxy-3-0Xo-23, 24- Mitsubishi dinorchola 4, 17-diene-22-oic Table 9.4 Some examples of mutants used industrially for the removal of the side chain of sterols 9. 4 Specific steroid interconversions and reactions In section 9.3, we discussed in general terms the use of microbial metabolism to selectively remove the side chain from sterols to pre steroids. This removal may also be accompanied by some modification to the ring structure. We did not, however, discuss in any detail any specific reactions. In this section we will focus on some specific reactions Before we begin this discussion, see how many types of enzyme catalyse sterols/steroids.(Do this without looking at Table %i t specific modification of reactions you can think of that may be used to carry ou
Biotransformation of lipids 309 Organism Prlnclple Product USer Mycobacterium fottuitum 9a-hydroxyandrostQ-ene-4,17- Upjohn NRRL B-8119 dione M. fortuitum 4-androstene-3,17dione NRRL 8-1 1359,11045 M. fortuitum M. fortuitum FERM Pa09 NRRL B-8119 9a-hydroxy-3-oxo-23,24- dinorchol-4-ene-22-oI Upjohn Upjohn 3,9dihydroxy-9,1O-secoandrosta Mitsubishi -3,5-triene-17-one Mycobacterium parafortuitum 9u-hydroxyandrost4-ene-3,17- Mltsubishi FERM P-4926 dione M. parafortuitum 4-androstene-3,17dione MCI 0807 M. parafortuitum 3-oxo-23,24dinorchola-l,4- MCI 061 7 diene-22-01 Mitsubishi Mitsubishi Mycobacterium sp 1,4-androstadiene-3, 1 7-dione Searle NRRL 8-3683 Mycobacterium sp 4-androstene-3,17dione NRRL 8-3805 Searle Rhodocoms corallinus 3p-hydroxy-23,24dinorchol-5- Mitsubishi FERM P-4812 9n9-22-0k2 acid Arthrobader simplex 3-hydroxy-9-oxo-9, 1 0-sec FERM P-4477 pregna-1.33 Corynebacterium equi 9-a hydroxy-3-oxo-23,24- triene90carboxylic acid dinorchoIa-4,17diene-22-oic acid Mitsubishi Mitsubishi Table 9.4 Some examples of mutants used industrially for the removal of the side chain of sterols. 9.4 Specific steroid interconversions and reactions In section 9.3, we discussed in general terms the use of microbial metabolism to selectively remove the side chain from sterols to produce steroids. This removal may also be accompanied by some modification to the ring structure. We did not, however, discuss in any detail any specific reactions. In this section we will focus on some specific reactions. Before we begm this discussion, see how many types of enzyme catalysed reactions you can think of that may be used to carry out speafic modification of sterols/steroids. (Do this without looking at Table 95). n