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The kinetic properties of the glutamate dehydrogenase of Teladorsagia circumcincta and their significance for the lifestyle of the parasite

Citation

Muhamad, N and Simcock, DC and Pedley, KC and Simpson, HV and Brown, S, The kinetic properties of the glutamate dehydrogenase of Teladorsagia circumcincta and their significance for the lifestyle of the parasite, Comparative Biochemistry and Physiology. Part B, Biochemistry and Molecular Biology, 159, (2) pp. 71-77. ISSN 1096-4959 (2011) [Refereed Article]


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DOI: doi:10.1016/j.cbpb.2011.01.008

Abstract

Like other nematodes, both L(3) and adult Teladosagia circumcincta secrete or excrete NH(3)/NH(4)(+), but the reactions involved in the production are unclear. Glutamate dehydrogenase is a significant source NH(3)/NH(4)(+) in some species, but previous reports indicate that the enzyme is absent from L(3)Haemonchus contortus. We show that glutamate dehydrogenase was active in both L(3) and adult T. circumcincta. The apparent K(m)s of the L(3) enzyme differed from those of the adult enzyme, the most significant of these being the increase in the K(m) for NH(4)(+) from 18mM in L(3) to 49mM in adults. The apparent V(max) of the oxidative deamination reaction was greater than that of the reductive reaction in L(3), but this was reversed in adults. The activity of the oxidative reaction of the L(3) enzyme was not affected by adenine nucleotides, but that of the reductive reaction was stimulated significantly by either ADP or ATP. The L(3) enzyme was more active with NAD(+) than it was with NADP(+), although the activities supported by NADH and NADPH were similar at saturating concentrations. While the activity of the oxidative reaction was sufficient to account for the NH(3)/NH(4)(+) efflux we have previously reported, the reductive amination reaction was likely to be more active.

Item Details

Item Type:Refereed Article
Research Division:Biological Sciences
Research Group:Biochemistry and Cell Biology
Research Field:Enzymes
Objective Division:Animal Production and Animal Primary Products
Objective Group:Livestock Raising
Objective Field:Sheep - Meat
Author:Brown, S (Dr Simon Brown)
ID Code:75728
Year Published:2011
Web of Science® Times Cited:6
Deposited By:Health Sciences A
Deposited On:2012-02-13
Last Modified:2012-05-24
Downloads:0

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