The Haemoglobins 0/ Ascaris lumbricoides 



var suis 



H. E. DAVENPORT 



Two distinct haemoglobins have been extracted from Ascaris 

 lumbricoides. Both have a very high oxygen affinity and neither 

 can be completely deoxygenated in vacuo. The oxygen dissociation 

 velocity was measured. Perienteric fluid haemoglobin in presence 

 of Na 2 S 2 4 at pU. 6, 20-5°C is half deoxygenated in 150 sec. 

 compared with 0-008 sec. for sheep haemoglobin. With body wall 

 haemoglobin the reaction is more rapid ; atpH 6, 3°C,t 50 = 80 ± 10 

 sec. The reaction is accurately unimolecular and its rate independent 

 of the concentration of the reducing agent. It is therefore a de- 

 oxygenation and not a true reduction. The deoxygenation velocity 

 of perienteric fluid haemoglobin increases with pH between pH 5 

 andpH 9 and has a temperature coefficient of 5. Carbon monoxide 

 dissociates from the haemoglobins more rapidly than oxygen ; 300 

 times more rapidly from perienteric fluid haemoglobin at 3°C, 

 pH 6. By its oxidative metabolism the parasite is capable of 

 deoxygenating the body wall haemoglobin which may have some 

 significance as a short period store of oxygen. 



The presence of two distinct haemoglobins in Ascaris lumbricoides, 

 the large roundworm of the pig, was recorded by D. Keilin 1 . One 

 haemoglobin occurs in the perienteric fluid and the other in the body 

 wall of the parasite. They differ from each other, and from the 

 haemoglobin of the host, in the position of their absorption bands. 

 Perienteric fluid oxyhaemoglobin has the a band at 5784A compared 

 with 5798A for the body wall pigment. 



The nature of the metabolic processes in Ascaris, whether aerobic 

 or anaerobic, has been for many years the subject of controversy. 

 Recently H. Laser 2 has shown that the oxidative enzyme systems of 

 the parasite are well adapted to function at low oxygen tensions. 

 The possibility that the worm haemoglobins participate in supplying 

 the low oxygen requirement appeared to justify a study of their 

 properties. 



The concentration of the haemoglobins is low and subject to con- 

 siderable individual variation but the absorption bands of oxyhaemo- 

 globin are always visible when worms are observed spectroscopically 

 against a strong light. An average sample of the perienteric fluid 



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