FREE AMINO ACIDS IN NERVOUS TISSUE 481 
TABLE IV 
ETHANOLAMINE, ITS DERIVATIVES, AND “PHOSPHATIDE SERINE” IN BRAIN AND NERVE 
Concentrations in s«moles/g. Reference numbers indicated between ( ). 




ee ee oe 7 Vi eit ep 
Man Frontal lobe | Mian (G2 771) | 1.05 (127) | 
Cattle | Brain | | 2(32) | 6.9 (32) 
Sheep Brain | ae , 24 8:9), 11.7 
| (36, 45) (36, 45) 
Dog Brain 1.2 (157) 
Cat Brain 3.4 (160) | 3.0 (160) | 3.9 (161) 18-23 6-12 
| | | (9, 36, 124) | (9, 36, 124) 
Rabbit Brain | 2.23.0 | 
| (154, 155) | | 
Guinea-pig | Brain | 23 (36) 3.5 (36) 
Rat | Brain 0.2 (51) | 0.95-2.9 0.I-1.0 | 
| ING is fel Rito, CVA (5,118, 126) | 
| 118, 126, 135, 
155) 
Hen Brain | I.0—3.25 0.80, 1.16 
| (TOs 12 Oris) (mon 126) 
Fish Brain 1.25 (126) 0.79 (126) 
Tortoise Brain | 0.72 (126) 0.69 (126) 
Frog Brain | 1.49 (126) 1.44 (126) 
Hen Spinal cord 0.48 (16, 135) | 0.61 (16) 
Hen Sciatic nerve | 0.19 (135) 
| 
| 






amine®> *!, 9, 119. Large amounts of PE in cow!”? and ox" brain have been reported 
though quantitative results are lacking. There is a decrease in PE in the developing 
rabbit?? and human!’ brain. The distribution of GPE and PE in parts of the human 
brain has been studied; variations in PE content are very large’”’. 
It should be noted here that the phospholipids designated as “cephalins” by earlier 
workers (cf. ref. 53) are now known to consist of mixtures of phosphatidylethanol- 
amine, phosphatidylserine, ethanolamine acetal phosphatide, serine acetal phospha- 
tide, diphosphoinositide (cf. refs. 43, 53, 107), and other lipids as yet uncharac- 
terized*4, 35, 77, Each of the substances noted is, in fact, a family of related substances 
differing only in the composition of the fatty acids and aldehydes attached to the 
glycerol moiety (cf. refs. 43, 53, 107), so that it is not possible in most cases to speak 
of specific compounds. For the purpose of the present notes, it is of interest only 
to give some indication of the amounts of ethanolamine and serine present in brain 
in lipid form. Accordingly, values are given in Table IV for the concentrations of 
what are here termed “phosphatide-ethanolamine” and “phosphatide-serine”. These 
figures are based on analyses of total lipid or total phospholipid extracts, and thus 
include ester and acetal phospholipid. The difficulties involved in the analysis of 
lipids for serine and ethanolamine content are discussed by OLLEy!8; DITTMER 
et al.°** have recently made a critical study of the appropriate conditions for such 
analysis, and DAwson*® has devised a procedure, using mild hydrolysis and chro- 
matography, for the determination of all of the phospholipids. 
References p. 482/485 
