Isotope Discrimination by Ribulose 1,5-Diphosphate Carboxylase: No Effect of Temperature or HCO(3) Concentration.
Carbon 13 isotope discrimination by ribulose 1,5-diphosphate carboxylase from soybean (Glycine max [Merr.] cv. Amsoy) was studied as a function of temperature, bicarbonate concentration, and pH. None of these factors affected the degree of discrimination against (13)C. The average delta(13)C was -28.3%, a value close to that found for whole C(3) plants. The zero temperature response observed here with ribulose 1,5-diphosphate carboxylase corroborates data from whole plants. The lack of effect of bicarbonate concentration on discrimination is consistent with both current theories of alternate forms of carboxylase.
Christeller
J T
JT
Plant Physiology Division, Department of Scientific and Industrial Research, Palmerston North, New Zealand.
Laing
W A
WA