272 T. W. GOODWIN 



2CH3COOH > 2CH3COSC0A > CH3COCH,COSCoA + CoASH 



Co/ 

 ( 



r 



Acetate Acetyl-CoA Acetoacetyl-CoA 



CH3COSC0A 



CoASH 



CH3C(OH)CH,CH20®<p-^CH3C(OH)CH,CH,OH y^^ CH3C(OH)CH,COSCoA 



I / \ I / \ I 



CH2COOH ADP ATP CH.COOH TPN TPNH, CH.COOH 



Mevalonic acid Mevalonic acid /3-Hydroxy-^- 



5 -phosphate methylglutaryl-CoA 



Mn'+ 



-ATP 

 'A DP 



ATP A DP 



CH3C(6h)CH,CH,0-®-0-® s^<f > CH3C-CH,CH,0-®-0-® 



CH.COOH ^0= ^' CH, 



Mevalonic acid Isopentenyl pyrophosphate 



5 -pyrophosphate 



Fig. I. The conversion of acetate into isopentenyl pyrophosphate. 



acetate are outlined in Fig. i. Experiments showing that isopentenyl 

 pyrophosphate is also involved in carotenoid biosynthesis have not yet 

 been reported ; however, there seems little doubt that it is an intermediate 

 because isotope experiments with various carotenogenic preparations have 

 shown that acetate, ^-hydroxy-/3-methylglutarate and mevalonate are all 

 incorporated in the expected manner (see Goodwin [2, 3].) 



CH3\ 



C— CH .,CH..O— ®— O— ® > 



CH./ 



Isopentenyl pyrophosphate 



CH3X CH3\ 



^C=CHCH.,0®-0-®+ ;CCH,CH,0-e/-0— ®- 



CH3/ " chX 



Dimethylallyl pyrophosphate 



-®— ® 



- '^CCH,,CH..Orpi— O— (P)+ '^)C=CHCH.,CHC=CHCH,0®— O— ® 

 CH./ " ' CH3/ 1 



CH3 



,^->-® — ® Geranyl pyrophosphate 



CH3\ 



/C=CHCH..CHC=CHCH.,CHC=-CHCH,0— ®— O— ® 



CH3/ I I 



CH3 CH3 



Farnesyl pyrophosphate 

 Fig. 2. The conversion of isopentenyl pyrophosphate into farnesyl pyrophosphate. 



