Comparative Study of Tadpole and Frog Glutamate Dehydrogenases

Barbara O Wiggert,Philip P Cohen

doi:10.1016/s0021-9258(18)96981-4

Barbara O Wiggert, Philip P Cohen

Open Access

https://doi.org/10.1016/s0021-9258(18)96981-4

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Abstract

Abstract 1. There is approximately a 10-fold increase in the specific activity of liver glutamate dehydrogenase during the spontaneous metamorphosis of tadpoles (Rana catesbeiana). 2. Comparative studies of glutamate dehydrogenases from premetamorphic tadpole liver and adult frog liver revealed differences in kinetic constants for DPN and TPN, in the effect of temperature on initial rates with DPN as coenzyme, in the crude molecular weights estimated from sucrose density centrifugation, and in relative reactivities with l-amino acids other than glutamate. 3. An antibody produced in rabbits against crystalline frog liver glutamate dehydrogenase precipitates glutamate dehydrogenase preparations from frog, tadpole, beef, and chicken liver and affects their reaction kinetics in a similar manner.

Highlights

M Tris-acetate, pH 8.0; 1 X 10-s M EDTA; 2 X 1O-2 M cr-ketoglutarate; 5 x lo+? M NH&l; and 5 x 1OV M DPNH was 2.5 x lop[4] mmoles of DPN produced per min per mg of protein, or about lOTo of the specific activity found with the first fraction of crystals of frog liver glutamate dehydrogenase (1)
Two weeks after the second subcutaneous injection, a series of five intravenous injections, containing 2 mg of crystalline frog glutamate dehydrogenase dissolved in 0.5 ml of 0.15 M NaCl, were administered 2 to 3 days apart
Increase in XpeciJic Activity During Spontaneous Metamorphosis-It has been previously reported by DeGroot and Cohen (3)

Summary

SUMMARY

1. There is approximately a IO-fold increase in the specific activity of liver glutamate dehydrogenase during the spontaneous metamorphosis of tadpoles (Rana cafesbeiana). 2. Compara.tive studies of glutamate dehydrogenases from premetamorphic tadpole liver and adult frog liver revea.led differences in kinetic constants for DPN and TPN, in the effect of temperature on initial rates with DPN as coenzyme, in the crude molecular weights estimated from sucrose density centrifuga.tion, and in relative reactivities with L-amino acids other than glutamate. Frog liver glutamate dehydrogenase has been crystallized and characterized (1, 2), and it has been determined that the activity of this enzyme increases significantly during thyroxine-induced metamorphosis of tadpoles (3). The present studies were undertaken to determine whether or not any differences exist between glutamate dehydrogenase derived from premetamorphic tadpoles, which are ammonotelic, and that from adult frogs, which are ureotelic. Frieden (4) has recently reported some experiments in which tadpole liver glutamate dehydrogenase was compared with glutamate dehydrogenase from other sources

PROCEDURE

RESULTS

X 1’F M 2 x 10-4 M