However, in experiments aimed at determining fractionation factors, only a small fraction of the reactant is typically allowed to transform to the product to avoid isotope distillation.
In our cellular fractionation experiments we can always observe a small fraction of Bcl-xL located to the microsomal light membrane fraction (Fig. 2 and data not shown).
Size fractionation of the coarsely ground barley showed that 40% of the total amount of OTA was present in a small fraction of fine particles with a strong tendency to aggregate or stick to equipment and containers.
Also, cell fractionation/Western blot studies revealed that a smaller fraction of the K-Ras in Icmt-/ cells was associated with the membranes.
Since pY proteins comprise only a very small fraction of cellular proteins, an additional cell fractionation step was combined with SH2 domain affinity purification step to isolate proteins for mass spectrometric (MS) analyses.
Fifty adult flies were manually homogenized in a microfuge tube with a small pestle in subcellular fractionation buffer (220 mM mannitol, 68 mM sucrose, 20 mM HEPES (pH 7.4), 80 mM KCl, 0.5 mM EGTA, 2 mM Mg(CH3COO 2, and Sigma protease inhibitor cocktail (Sigma #P8340)).
The δ34SSO4 values from both the biological and abiotic anaerobic experiments indicated a small but significant sulfur isotope fractionation (∼−0.7‰) in contrast to no significant fractionation observed from any of the aerobic experiments.
Small-scale fractionation was carried out as described previously [ 86].
The HCl hydration that followed caused a small degree of Cl isotope fractionation (3 6‰ 23.
In each fractionation experiment, a small proportion of the cell sample was lysed in RIPA buffer (150 m m NaCl, 50 m m Tris HCl, pH 7.5, 1% Nonidet P-40, 0.1% SDS, 0.5% sodium deoxycholate) supplemented with a protease inhibitor cocktail (Roche) for subsequent analysis of the expression level of exogenous proteins by western blotting.
