114 THE PHYSIOLOGY OF EARTHWORMS 



to be arginine phosphate (AP), and that this substance was the 

 phosphagen for all invertebrates, including annelids, to the 

 exclusion of the vertebrate counterpart creatine phosphate, save in 

 the echinoderms where both materials occur (Baldwin, 1949). The 

 methods used in the early investigations, however, were not 

 strictly specific and more improved techniques have recently shown 

 that more than one guanidine derivative acting as a phosphagen 

 can be obtained from invertebrates. Among the annelids tauro- 

 cyamine has been found in Arenicola, glycocyamine in Nereis 

 and lombricine in Lumhricus (Thoai and Robin, 1954). 



Earthworm muscles hydrolysed in 6N HCl for 8 hours at 110 °C 

 break down into their constituent parts, and among these Thoai 

 and Robin (1954) found the amino-acid serine and a number of 

 related guanido compounds, formed presumably in combination 

 with arginine. These guanido compounds included guanido-ethyl- 

 seryl-phosphoric di-ester which they named lombricine. The 

 substance occurs alone in the body wall muscles, but in conjunc- 

 tion with arginine in the alimentary canal musculature. The 

 associated phosphagen, phospho-guanido-ethyl-seryl-phosphate is 

 also obtainable from the same tissues. This is evidently the more 

 important energy store because of its widespread distribution in 

 the tissues, particularly the muscles from which AP is absent. 



Since the initial identification of lombricine by Thoai and Robin 

 (1954) the structure, properties and bio-synthesis of lombricine 

 have been elucidated by Ennor and his colleagues (1958, 1959, 

 1960) and by Pant (1959). 



Pure crystalline lombricine has been isolated from earthworms 

 by means of ion exchange, column and paper chromatography 

 (Rosenberg and Ennor, 1959, Pant, 1959). At the same time 

 Rosenberg and Ennor (1959) found serine di-ethyl phosphate 

 (SEP) in tissue extracts, and postulated for it the role of biological 

 precursor to lombricine, since it is present in only small amounts 

 and by non-enzymic guanylation gives rise to a product indistin- 

 guishable from natural lombricine. In the biological material the 

 amidine group of lombricine may come originally from arginine 

 by way of transamidination (Fig. 35). 



A surprising feature of the chemistry of lombricine was un- 

 covered by Beatty, Magrath and Ennor (1959). Among the amino- 

 acids occurring naturally in living tissues only the L-enantiomorph 



