PURIFICATION, CHARACTERIZATION, AND HYDRODYNAMIC PROPERTIES OF ARGININE KINASE FROM GULF SHRIMP (PENAEUS-AZTECUS)

Arginine kinase from the tail muscle of the Gulf shrimp (Penaeus aztec us) was purified to apparent homogeneity, using a rapid, high-yield me thod, The protein exhibits a molecular weight of 40 kDa according to t he methods of gel filtration and gel electrophoresis in sodium dodecyl sulfate, also indicating that arginine kinase from shrimp is a monome r. The amino acid content of arginine kinase from shrimp is similar to arginine kinases from several species and to creatine kinase from rab bit muscle. Arginine kinase derivatized at the reactive sulfhydryl wit h -(4'-(iodoacetamido)anilino)naphthalene-6-sulfonic acid exhibits sig nificant changes in fluorescence anisotropy only in the presence of th e guanidino substrate and the so-called ''dead-end complex'' containin g arginine + MgADP, Several compounds structurally similar to arginine , e.g., ornithine do not interact with arginine kinase, suggesting a n arrow specificity for substrate binding. The most suitable description of the decay of the fluorescence of arginine kinase derivatized with (acetyl)-amino)ethyl)amino]naphthalene-1-sulfonate (AEDANS-AK), from a mong discrete and distributed models, is a triple exponential discrete decay, The presence of the dead-end complex only marginally increases the rate of decay, but significantly shifts the magnitude of the pree xponentials (amplitudes) between the two major decay components, One i nterpretation of these results is that multiple conformational isomers may occur, in which the relative concentrations are dependent upon th e presence of the dead-end complex, Measurement of the time-dependent anisotropy decay of AEDANS-AK reveals a two-term decay law with rotati onal correlation times of 0.88 and 15.2 ns, The slower component is cl ose to the theoretical value of 16.7 ns for an isotropic rotator of th e molecular mass of arginine kinase, This finding suggests that the ov erall conformation of arginine kinase may differ considerably from the prolate ellipsoidal subunits of the functionally analogous creatine k inase. (C) 1997 Academic Press.