Amino acid catabolism in the nematodesHeligmosomoides polygyrusandPanagrellus redivivus. 1. Removal of the amino group

Abstract

SUMMARYThe major transaminase inHeligmosomoides polygyrus, Panagrellus redivivusand rat liver was the 2-oxoglutarate-glutamate system, with relatively few amino acids acting as donors for the pyruvate-alanine and oxaloacetate–aspartate systems. The relative effectiveness of the different amino acid donors in the three transaminase systems was similar in all three tissues. BothH. polygyrusandP. redivivuscan oxidatively deaminate a range of L-amino acids, although D-amino acid oxidase activity was low. Serine and threonine dehydratase activity and histidase activity were present inH. polygyrusandP. redivivusand both nematodes were also able to deaminate glutamine, asparagine and arginine. When NAD(H) was the cofactor the glutamate dehydrogenases ofH. polygyrusandP. redivivusshowed similar regulatory properties to the mammalian enzyme. However, with NADP(H) the results were anomalous. The capacity of both nematodes to transaminate and oxidatively deaminate amino acids was broadly similar and comparable to mammalian tissue. Glutamate dehydrogenase is probably the major route for deamination in these nematodes. A complete sequence of urea cycle enzymes could not be demonstrated in eitherP. redivivusorH. polygyrus.