title: Arginine kinase and phosphoarginine, a functional phosphagen, in the rhabditoid nematode steinernema carpocapsae.
abstract: Moderate activity of arginine kinase was found in Steinernema carpocapsae, an entomopathogenic nematode. In the forward reaction, 4.60 and 3.12 micromol ATP/min/mg protein was produced in infectious third-stage juveniles (J3s) and adult nematodes, respectively. For the reverse reaction, 3.20 and 2.27 micromol phosphoarginine/min/mg protein was produced by J3s and adults, respectively. The K(m)s for phosphoarginine and ADP were 0.73 and 0.42 mM, respectively, in the forward reaction, whereas in the reverse reaction, the K(m)s were 0.37 and 2.35 mM for arginine and ATP, respectively, for the enzyme from J3s. The pH optimum for the forward reaction was 7.2 and 7.3 in J3s and adults, respectively. The pH optimum was elevated for the reverse reaction, 7.8 and 7.9-8.5 in J3s and adults, respectively. In the J3s, the in vitro optima for arginine kinase activity was correlated with the in vivo tissue pH in hypoxic (6.9) and aerobic (7.5) J3s estimated by in vivo flow 31P-NMR.
authors.affiliation: Department of Nematology, University of California, Riverside 92521, USA.
authors.forename: E G
authors.initials: EG
authors.lastname: Platzer
authors.forename: W
authors.initials: W
authors.lastname: Wang
authors.forename: S N
authors.initials: SN
authors.lastname: Thompson
authors.forename: D B
authors.initials: DB
authors.lastname: Borchardt
mesh_terms: D000332:Aerobiosis; D000367:Age Factors; D000693:Anaerobiosis; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives* / Q000378:metabolism; D001122:Arginine Kinase / Q000378:metabolism*; D004734:Energy Metabolism; D006863:Hydrogen-Ion Concentration; D009036:Moths / Q000469:parasitology; D019906:Nuclear Magnetic Resonance, Biomolecular; D009943:Organophosphorus Compounds / Q000378:metabolism; D010759:Phosphorus Isotopes; D017172:Rhabditoidea / Q000502:physiology*; D013379:Substrate Specificity
chemical_list: D009943:Organophosphorus Compounds; D010759:Phosphorus Isotopes; C015441:phospho-L-arginine; D001120:Arginine; D001122:Arginine Kinase