114 



BIOCHEMICAL STUDIES OF PHYLOGENY 



Creatine phosphate (CP) was present in many vertebrate muscles, 

 thus the Eggletons found it in the muscles of Amphioxus, dogfish, 

 plaice, frog, snake, tortoise, rabbit and guinea-pig. They were 

 unable to find it in any of the invertebrate muscle they studied 

 (Aurelia, Lumbricus, Aplysia, Pecten, Holothuria). Meyerhof 

 (1928) found that there was a phosphagen present in invertebrate 

 muscles but that it was not creatine phosphate but arginine 

 phosphate instead. This he found in Sipunculus, Pecten, Holothuria 

 and Stichopus muscle. 



NH.OP(OH) 2 



NR 



HN = C 



HN = C 



NH 



NH 



(CH 2 ) 3 + H 2 



(CH 2 ) 3 + H 3 P0 4 



CH.NH 2 



COOH 



Arginine phosphate 



CH.NrL 



COOH 



Arginine and phos- 

 phoric acid. 



Although it is not strictly within the scope of this book it might 

 be as well to indicate the function of the phosphagens. They act 

 as an energy reserve for muscle contraction. The phosphagens are 

 high-energy compounds and they can phosphorylate adenosine 

 diphosphate (ADP) to form adenosine triphosphate (ATP). 



ADP + CP = ATP + C 



When a muscle contracts and performs work, at some stage of the 

 contraction-relaxation cycle it uses up the ATP and converts it 

 to ADP. This ADP is reconverted to ATP by means of the 

 phosphagen. At a later stage, glycolysis (the breakdown of glucose 

 to carbon dioxide and water) brings about the synthesis of more 

 high-energy compounds and the phosphagen is re-formed. This 

 reaction CP + ADP = C + ATP is sometimes called the 

 Lohmann reaction and the reader can find more details in most 



