394 MAHLON B. HOAGLAND 



fer of amino acid from sRNA to protein, then this enzyme will be found 

 to be the essential missing link. The "S-protein" of Sachs and the incor- 

 poration enzyme of Beljanski and Ochoa may be such an enzyme which 

 has been fortuitously separated from the other components of the system. 

 Indeed, in none of the experiments quoted were these enzymes tested 

 in addition to sRNA and activating enzymes. Only the advent of a vigorous 

 protein synthesizing system, each of whose components may be clearly 

 separated one from the other, will give us the final answer to these ques- 

 tions. 



3. Note on the Occurrence of Certain 

 Nucleotide-Peptide Compounds 

 During the past few years a variety of amino acid or peptide-containing 

 nucleotide compounds have been described in the literature. Reith 192 has 

 found in ascites cells an aspartic acid-uridylic acid compound. Hansen 

 and Hageman have found in chicken liver a compound tentatively iden- 

 tified as adenosine diphosphoglutamic acid. 193 Hase et al. l9i have found 

 in yeast and chlorella cells peptides containing several amino acids chemi- 

 cally associated with oligonucleotides containing adenine, uridine, and 

 cytidine. Brown 195 has reported the occurrence of peptides containing 

 several amino acids associated with AMP in S. faecalis. Habermann, 196 and 

 Keil and Hrubesova 197 have found that RNA prepared by the phenol method 

 from yeast, ascites tumor cells, mouse liver, and brain contain strongly 

 bound peptides released by ribonuclease. They refer to other instances 

 of occurrence of such peptides. In most of these cases the acidic amino 

 acids are prominent, and the bond between peptide and nucleotide is 

 relatively alkali-resistant. In none has the nature of the linkage between 

 amino acids and nucleotides been identified. A different situation has 

 been reported by Koningsberger et al. m who have found carboxyl activated 

 amino acid-oligonucleotide compounds in extracts of baker's yeast. The 

 bond between nucleotide and amino acid has the lability characteristics 

 of transfer RNA-amino acid compounds but the material is dialyzable. 

 The relationship of such compounds to those apparently involved as inter- 

 mediates in cell wall synthesis 199 " 201 is not known. 



J" W. S. Rieth, Nature 178, 1393 (1956). 



193 R. G. Hansen and E. Hageman, Arch. Biochem. Biophys. 62, 511 (1956). 



194 E. Hase, S. Mihara, H. Otsuka, and H. Tamiya, Biochim. et Biophys. Acta 32, 298 

 (1959). 



195 A. D. Brown, Biochem. J. 71, 5P (1959). 



196 V. Habermann, Biochim. et Biophys. Acta 32, 297 (1959). 



197 B. Keil and M. Hrubesova, Chem. listy 49, 274 (1955). 



198 y y Koningsberger, C. O. Van der Grinten, and J. T. G. Overbeek, Biochim. et 

 Biophys. Acta 26, 483 (1957). 



199 J. Mandelstam and H. J. Rogers, Nature 181, 956 (1958). 



200 R. Hancock and J. T. Park, Nature 181, 1050 (1958). 



