A mathematical model for the analysis of the turnover of protein mixtures. II. Modified power functions as special models.

In part 1 of this series a model for the protein turnover characterized by an inhomogeneous protein pool with a distribution of turnover constants was developed. This model is mathematically described, taking into account that the protein turnover is experimentally determined almost exclusively by tracer experiments, but a system of integro-differential equations. The analytical solution of this system of equations is elaborated for 3 special cases: tracer elimination from the protein pool after pulse labelling, tracer accumulation due to continuous labelling, and elimination after stopping this continuous incorporation of tracer. The applicability of the resulting modified power function is tested using an example for the literature (Garlic et al.: Biochem. J. 156, 657 (1976)) and computer generated data. On this background the existence of several classes of proteins computer generated data. On this background the existence of several classes of proteins with typical life times is discussed. Finally, the general applicability of power functions for tracer kinetic problems is treated from the point fo view of the results obtained in this paper.