II. CHEMISTRY 189 



the ratio is essentially the same for hydrated ergosterol, 1.30, as for an- 

 hydrous ergosterol, 1.29. 



The specific rotations of twenty-one ergosteryl esters are given in Table 

 IV. In several instances the values seem anomalous, in that they are widely 

 different from what would be expected on the basis of differences in molecu- 

 lar weight. This does not necessarily indicate contamination or error, for 

 similar anomalies have l)een observed in cholesterol esters. ^^^ 



The absorption spectrum of ergosterol. Fig. 8, reveals the four commonly 

 recognized bands with maxima at 262, 271, 282 and 293.5 m/x. In addition 

 to these, there are four other bands, or inflections, which can be seen clearly 

 only in more concentrated solutions. Smakula^^^ reported a band at 232 

 m/i, and Sumi^^^ noted an inflection at 250 m/x. Hogness et al}^^ located the 



TABLE VI 

 Optical Rotation of Ergosterol" 



Solvent [a]^°6, H^° Ratio 



Chloroform 



Benzene 



Ethyl acetate 



Ether 



Alcohol (absolute) 



Acetone 



" Data from Bacharach et al.^^^ on a commercial grade of ergosterol. 



latter band at 252 m/z and found two more at 325 and 337.5 myu. The fact 

 that ergosterol absorbs, even slightly, these longer waves, probably accounts 

 for the otherwise unexplained destructive effect of subdued daylight. 



Hogness et aU^^ and Huber et al?^^ compared the absorption spectra of 

 ergosterol in several solvents. The wavelengths of the maxima were essen- 

 tially the same in alcohol, hexane, and isooctane. The extinction coefficients 

 were highest in alcohol and hexane, and a little lower in isooctane. In 

 chloroform the extinction was considerably lower, and the position of the 

 maxima shifted 3 m/x toward the visible region. 



Sterol color reactions depend on the double bond systems and hence are 



261 R. L. Shriner and L. Ko, J. Biol. Chem. 80, 1 (1928). 



2«2C. Liebermann, Ber. 18, 1804 (1885). 



2" F. A. Askew, R. B. Bourdillon, H. M. Bruce, R. K. Callow, J. St. L. Philpot, and 



T. A. Webster, Proc. Roy. Soc. (London) B109, 488 (1932). 

 26* M. Sumi, Biochem. Z. 204, 397 (1929). 

 265 T. R. Hogness, A. E. Sidwell, Jr., and F. P. Zscheile, Jr., /. Biol. Chem. 120, 239 



(1937). 



