Theoretical fitting of energetics of CAM path to calorimetric data

Abstract

The objective is to test fit of calorimetric data on Crassulacean acid metabolism (CAM) to current concepts in the field. Calculations, done by using maximum observed rates of nocturnal acid accumulation, and ΔH values for reactions in known processes of acid accumulation, were used to predict heat rates. The predicted heat rates were compared with heat rates measured by microcalorimetry. This investigation involved nine diverse species of CAM plants. In six species, calculated and measured values were similar. Fitting the titratable acidity data to the microcalorimetric results, accounts for the expenditure of up to 7.5 molecules ATP per molecule of malate stored in vacuole. Of these 7.5 ATP molecules, fitting suggests 3.5 are derived through the truncated glycolytic path of CAM and up to 4 ATP are generated through the processing of starch through to electron transport