83 



the difference between Li^ and Na+ we better use a less sensitive 

 dye, such as acridine orange. If LiCl, NaCl, and KCl are added in 

 0.1 M concentration to a (O.IQ-^ M) watery solution of acridine 

 orange and the solutions are frozen in test tubes and held under 

 the UV lamp, the first, containing LiCl, will show an intense red 

 glow while the others will show practically no light emission. 

 The disturbance caused in the developing embryo could thus have \ 

 its explanation in the disturbance of the water structures which 

 may be instrumental in the decoding and transmission of the in- 

 formation contained in genes. 



The dimensions of the ammonium ion are similar to those of 

 K". It was found, accordingly, that NH4CI, similarly to KCl, 

 caused no disturbance in the phosphorescent behavior of rhodamin. 



GLUTATHIONE 



One of the most puzzling cell components is glutathione which 

 is present according to F. G. Hopkins in normal tissues in as high 

 concentrations as one mM. Though various interesting reactions 

 of glutathione have been described its real biological meaning is 

 still unknown. It is assumed that it acts as redox buffer keeping 

 with its own SH groups those of the protein in reduced condition. 

 This, however, only shifts the real problem instead of solving it 

 because then we may ask: what has the SH to do in proteins? It 

 certainly plays a most important role in its function. Many 

 enzymes are "SH-enzymes," the intactness of the SH group of 

 which is indispensable for activity. There are even S-containing 

 hormones (oxytocin, vasopressin, insulin) which may exert their 

 action in a reduced form. So we are faced here with a wider prob- 

 lem, that of the biological meaning of sulfur in general. 



Glutathione, when tested for its influence on the excitation of 

 rhodamin in the ways described in the previous pages, yielded no 

 clue. Added to the solutions of this dye it produced the same 

 action as thiamine: increased phosphorescence, an action which is 

 not specific and is mainly a function of molar concentration. 



