The evaluation of the rates of biological processes from tracer kinetic data. I. The influence of labile metabolic pools
The effects of small, metabolically labile, intermediate pools on kinetics of isotope uptake and release are presented. The primary influence of such pools is to effect a coupling between components that are both derived and synthesized from the pool. Probably the most significant interaction is that of a component with itself. This is called recycling. ft is shown that no matter how an isotope experiment is conducted, the true turnover rate or true half-life cannot be calculated without information additional to the time course of activity in the component under study. It is noted that the presence of the pool does not alter the shape of kinetic curves. Therefore, the existence of such a pool cannot be adduced from kinetic experiments, and consequently the interpretation of the observed rate constant or The equivalent half life as either a true value or an apparent value is equivocal. Methods to evaluate the true turnover rates are considered. When two components are both connected to the same small pool, the turnover of one influences the other. The conditions determining whether this interaction is significant are discussed. Such coupling adds an additional term to, and changes the rate constants of, the original equation. If there are many components, there are many additional terms. It is shown that under certain conditions, the terms due to components other than the one under study may be combined in a way to give great simplification. Finally, the influence of growth on tracer kinetics is considered. A treatment employing specific activity data, yielding the turnover rate constant for synthesis is presented. This treatment is nearly correct for systems changing by a limited factor, say less than two fold. A procedure employing total activity measurement which yields the turnover rate constant for degradation is also presented.
- Research Organization:
- Univ. of Florida, Gainesville
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-17-005726
- OSTI ID:
- 4739741
- Journal Information:
- Journal of Theoretical Biology, Journal Name: Journal of Theoretical Biology Journal Issue: 2 Vol. 3; ISSN 0022-5193
- Publisher:
- Elsevier
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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