94 



GENERAL BIOCHEMISTRY 

 CH3 



CH3 



CH3 



CH— CH=CH— GH— CH 



H2 CHa 



C 



H2. 



c 



H2 CH3 



G 



G 



GH3 



H2C 



GH 



G 



/H 



GH2 

 -GH., 



HO— C G GH 



I\g/ \c/ 



H H2 H 



ergosterol 



A number of sterols have been isolated from plants. Among these 

 are sitosterol, found in wheat embryo, barley, corn, and cottonseed; 

 stigmasterol, isolated from coconut and soybeans; and spinasterol from 

 spinach and cabbage. All 3 sterols mentioned have 29 carbons in the 

 molecule, each having a 10-carbon side chain. They differ only with 

 respect to the number and position of the double bonds in the mole- 

 cule. 



Bile contains a number of steroids, the most abundant of which is 

 cholic acid (3,7,12-trihydroxycholanic acid). Most frequently the 

 carboxyl group of cholic aid is conjugated with glycine or taurine to 



CH 



,T 



OH CH(rHo)2C00H 



CH, I 



CH(CH2)2C— NH- CH2CH2— SOgNa 



sodium taurocholate 

 (a bile salt) 



