91 



Carotenes and Carotenoids 



that Mucor hiemalis uses acetate for the production of ^-caro- 

 tene. The product derived from C"-labeled acetate has been 

 partially degraded, and the following partial distribution pattern 

 demonstrated : 



i3-carotene 

 o Carbon atom from the methyl group of acetate 

 • Carbon atom from the carboxyl group of acetate 



Mevalonic acid is an effective carotene precursor in at least 

 certain microorganisms. ''■ '' In this connection it is noteworthy 

 that in Phyconiyces hlakesleeanus and in Mucor hiemalis the 

 production of sterols and carotenoids always runs proportion- 

 ally.* The scheme shown below has been proposed for the 

 mode of condensation. - 



HOOC- 



OH 



\ 



OH 



COOH 



Leucine has been known for many years to have ketogenic 

 and carotenogenic properties to a greater extent than other 

 amino acids. The discovery of mevalonic acid facilitated an 



*E. C. Grob and R. Butler, Helv. Chim. Acta 39 1975 (1956). 

 ■^E. C. Grob, Chimia 10 73 (1956). 



6 G. D. Braithwaite and T. W. Goodwin, Biochem. J. 66 31p (1957). 

 ^E. C. Grob, Chimia 11 338 (1957). 



* E. C. Grob, M. Bein and W. H. Schopfer, Bull. soc. chim. biol. 

 33 1236 (1951). 



