Kinetics of Heat Aggregation of Proteins

B. I. Kurganov

Bakh Institute of Biochemistry, Russian Academy of Sciences, Leninskii pr. 33, Moscow, 117071 Russia; fax: (095) 954-2732; E-mail: inbio@glas.apc.org

Received January 26, 1998

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The mechanism of heat aggregation of proteins proposed by the author involves the stage of irreversible denaturation, the stage of nucleation, and the stage of growth of aggregates. It was shown that the initial parts of the kinetic curves of aggregation followed by the increase in absorbance (A) or intensity of light scattering (I) are linearized in coordinates {dA/dt; t} and {A; t²} (or, respectively, in coordinates {dI/dt; t} and {I; t²}). The slope of these linear anamorphoses is proportional to the product of the rate constant of irreversible denaturation and the rate constant of growth of aggregates. The mechanism of heat aggregation proposed is fulfilled for pig heart citrate synthase. The dI/dt versus t curves for heat aggregation of glycogen phosphorylase b from rabbit skeletal muscles display a lag period whose appearance is caused by intramolecular predenaturational changes in the enzyme molecule.

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KEY WORDS: protein aggregation, denaturation, citrate synthase, glycogen phosphorylase

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