64 David Shemin and Jonathan Wittenberg 



atom of glycine, the squares represent those carbon atoms 

 derived from the methyl group of acetic acid, the filled 

 circles represent the carboxyl group of acetic acid, and the 

 carbon atoms which are in main derived from one of the 

 carbon atoms of acetate and partly from the other are 

 appropriately designated. 



REFERENCES 



Altman, K. I., Casarett, G. W., Masters, R. E., Noonan, T. R., and 



Salomon, K. (1948). J. bioL Chem., 176, 319. 

 Andrews, J. S., Corwin, A. H., and Sharp, A. G. (1950). J. Amer. 



chem. Soc, 72, 491. 

 Bloch, K., and Rittenberg, D. (1945). J. biol. Chem., 159, 45. 

 Buchanan, J. M., and Hastings, A. B. (1946). Physiol. Rev., 26, 120. 

 Button, A. W. J., Bentley, R., and Rimington, C. (1948). Biochem. 



J., 43, xlix. 

 Grinstein, M., Kamen, M. D., and Moore, C. V. (1948). J. biol. 



Chem., 174, 767. 

 Lemberg, R., and Legge, J. W. (1949). HemMin Compounds and Bile 



Pigments. New York: Interscience, 

 LiFSON, H., LoRBER, V., Sakami, W., and Wood, H. G. (1948). J. biol. 



Chem., 176, 1263. 

 MuiR, H. M., and Neuberger, A. (1949). Biochem. J., 45, 163. 

 MuiR, H. M., and Neuberger, A. (1950). Biochem. J., 47, 97. 

 Radin, N. S., Rittenberg, D., and Shemin, D. (1950a). J. biol. Chem., 



184, 745. 

 Radin, N. S., Rittenberg, D., and Shemin, D. (19506). J. biol. 



Chem., 184, 755. 

 Shemin, D., Lontjon, I. M., and Rittenberg, D. (1948). J. biol. 



Chem., 173, 799. 

 Shemin, D., London, I. M., and Rittenberg, D. (1950). J. biol. 



Chem., 183, 757. 

 Shemin, D., and Rittenberg, D. (1945). J. biol. Chem., 159, 567. 

 Shemin, D., and Rittenberg, D. (1946). J. biol. Chem., 166, 621, 627. 

 Shemin, D., and Wittenberg, J. (1951). J. biol. Chem. In press. 

 Turnt:r, W. J. (1940-41). J. Lab. din. Med., 26, 323. 

 Wittenberg, J., and Shemin, D. (1949). J. biol. Chem., 178, 47. 

 Wittenberg, J., and Shemin, D. (1950). J. biol. Chem., 185, 103. 

 W^ooD, H. G. (1946). Physiol. Rev., 26, 198. 

 Wood, H. G. (1948). Cold Spr. Harb. Sym. quant. Biol, 13, 201. 



DISCUSSION 



Neuberger: I am wondering whether the activity in the pyrrole rings 

 which is derived from carboxyl-labelled acetate could not be explained 

 without assuming this hypothetical 4-carbon compound. If, for example, 

 the reaction of succinic acid with COj to produce ketoglutarate were 



