172 



THE CELL AND PROTOPLASM 



ture of the particles in protoplasm, a 

 rather interesting picture is obtained. To 

 gain this, however, it seems necessary to 

 examine the structure of the chain more 

 closely than to merely determine its gross 

 dimensions. A chain with a molecular 

 weight of about 36,000 will serve arbitra- 

 rily as a convenient size, and it happens to 

 be a dimension which appears many times 

 in the literature where molecular weights 

 as determined by several different experi- 

 mental methods are reported for many sorts 



of i^roteins. The materials employed for 

 these determinations are usually "puri- 

 fied" proteins which have been removed 

 from the cell. They are salvaged portions 

 of the wreckage of protoplasm in almost 

 every instance. 



More than one kind of protein may be 

 obtained from the broken-down products 

 of protoplasm, for it seems probable that 

 within the cell some forms are normally set 

 aside from active protoplasm to serve spe- 

 cific purposes. The proteins of aleurone 



TABLE I 

 Diagram of Amino Acid Formulae 



AMINO ACID 



avONE 



^■AMINO- 



BUTyRIC ACID 



VALINE 



LEUCINE 



ISOLEUCINE 



SERINE 



CYSTEINE 



ASPARTIC ACID 



CL'JTAMIC ACID 



MaVKCT 



CMS 



STRuauRAL FORMULA 



H 

 H 



H-C— C- 



T" 



rf" 



H-CvH 

 H^ V 



H-C^ 



'\ H H 



H- 



rf' 



H V 

 »y H 



_a 



H 



HO-^c— -c— c; 



H— c — s— c — c 



HO 



/ 



HO 



c— C 



I \ 



H 



H 



I </ 



c— c 



OH 



OH 



H 



c— c 

 I \ 



N^ OH 



H 



I" 



H 



OH 



>H 



H 



c— c 



N\ OH 

 H 



,/ 



\ 



OH 



\ 

 OH 



\ 

 OH 



AMINO ACID 



MavCT 



CMS STRUCTURAL FORMULA 



P-HYDROXYCLUTAMIC 



LYSINE 



ARGININE 



HISTIDINE 



PHENYLALANINE 



TRYPTOPHANE 



PROLINE 



;c — c — c- 

 / I I 



"° H o'h 



y y ^ . 



-c — c — cH-c- 



-c -^— c — c — c-f c— c 

 I I I I I 



N H H H H 



c=c — c- 

 I 



H 



■c— c 



K oh 



H 



.^' 



\ 



oh 



<' \ 



^ 



.1 



/\ 



./ 



\ 



OH 



"-c-\-i- 



r^\r 



J 



H \. 



^c X 



<(\^\/- 



H 

 I 



-c^c- 



1 / 



-c — c 

 -ri^ OH 



H 



H 



c-c^ 



y \ °" 



H 



\ 



OH 



hAA: 



r 



OH 



