IIKVIKW Of LFFKBATUBB. 7 



\i ( 1.1. < >-IM; >i i i\-. 



Ry this name are designated those compound proteins which yield 

 true nucleins on pepsin digestion and which, on cleavage with alkali, 

 yield protein and nucleic acid. The nucleo-proteins seem to be 

 widely distributed in the animal body. They occur chiefly in the 

 cell nuclei, but they also often occur in the protoplasm. They may 

 p8Sfl into the animal fluids on the destruction of the cells; hence 

 nucleo-proteins have also been found in blood scrum. They may be 

 con-idered as combinations of a protein nucleus with a side chain 

 which Kossel" calls the "pro.-ietic irroup." This side chain, which 

 contains the phosphorus. yield> on tin 4 decomposition of many nucleo- 

 proteins. >iich as that from the yeasl cell ' or from the panen 

 besides nuclein ha>e>. al-o reducing substances, \N hich form crystalline 

 combinations with phenyl-hydra/.in. The nucleo-protems contain 

 from ()..") to l.ii per cent of phosphor 



The nucleo-proteins >plit into a nuclein and an albumin radicle and 

 the nuclein radicle i^ fnrt her split into nucleic acid and albumin. The 

 nucleic acid- on e yield in addition to the purin bases three 



simple pyrimidin derivative-, uracil. r\t>Mn. and thymin. In a 

 receni article by ( Kbornc and lle\l it appears ihat all but one- 

 sixteenth of the nitrogen of nucleic acid probably belong to ^uanin, 

 adcnin. c\ t>rm. and ura-il. of \\ Inch one molecule of each i> present 

 for even four atoms of pho>phoru->. 



It is important to dMin.uuUh between the nuele.-pniieins and the 

 {)seu.|( nucleo-pntein^. The latter bodies are obtained as an insolu- 

 ble residue on diircMion of certain nudeo-albumins or phospho-glyCO- 

 proieins with pepsin hydrochloric acid. They contain phosphoru- 

 but yield no nuclein bases. Amoni: the pseudo QUCleo-proteillS mav 

 be mentioned phospho-proteins and lecitho-proteins. The-e >ub- 

 stain -I'ten fed in the form of casein or vitellin in metabolism 



experiment-. 



M < 1.1 : 



The ireneric name of nuclein has been bestoued ujon a larire number 

 of very ditrerent orLTanic pho.sphonis compound.-, which are to be 

 found in all animal and vegetable tissues, beinir e>|)ecially abundant 

 in the nuclei of cells. The nuclein- contain about .') per cent of phos- 

 phorus and are formed by the cleavage of nueleo-protcin. The 

 nucleins are acids, and the phosphorus is given oil' as phosphoric acid 

 on boiling with water, and more rapidly on boilinir with alkalies or 

 acids. But the organic substances which are combined with the 



" An-h. Anal. Ph\>i<>l., Physiol. AM.. |V):j. j,. |."7. 

 *> Il)ii., 1S!H. j> 



ILuuiiutr-ien. Xt>. Ph\>i..l. Cli.-in . ISMI. /.'; : 19. 

 '/ Anu-r. .1. Phy<i..l.. L908, .'/ : 157. 



