Analytics Cell concentration was monitored by measuring the optical density (OD) at 600 nm or by gravimetry [26]. The 13C labelling pattern of the amino acids contained in the cell protein was determined as follows [27]. Cells were harvested during exponential growth phase at half-maximal optical density including a washing step in 0.9% NaCl solution, followed by lyophilisation. Subsequently, 4 mg of lyophilised cells was resuspended in 200 μl of 6 M HCl and incubated

at 110°C for 24 h. The obtained hydrolysate was neutralised by addition of 6 M NaOH and cleared of insoluble matter (0.2 μm centrifugal filter device Ultrafree MC, Millipore, Bedford, MA, USA). Subsequently, 50 μl of the hydrolysate was transferred to a 2 ml sample vial, lyophilised and derivatised at 80°C for 60 min with 50 μl N, N-dimethylformamide (Carl Roth, Karslruhe, Germany) containing 0.1% (v/v) VX-680 purchase pyridine and 50 μL N-methyl-tert-butyldimethylsilyl-trifluoroacetamide (MBDSTFA, Macherey-Nagel, USA). GC/MS measurements were carried out as described earlier [27]. Subsequent MS data processing was carried out according to Fürch et al. [18] and

Lee et al. [28, 29]. Preparation of cell extracts for enzyme activity measurements Cells were harvested by centrifugation at 10,000 g for 10 min, washed twice with 100 mM Tris-HCl (pH 7.0) containing 20 mM KCl, 5 mM MnSO4, 2 mM DTT and 0.1 mM EDTA, and then resuspended in the same buffer. Afterwards the cells were disrupted by sonification for 1 min using an ultrasonic disrupter (Sonifier W250 D, Branson, Danbury, USA) with an amplitude of 30%. Cell learn more debris was removed by centrifugation. The resulting crude cell extract was immediately used to determine specific enzyme activity. All operations were carried out on ice. Enzyme assays Enzyme activities in crude cell extract were measured spectrophotometrically. All compounds of the reaction mixture were pipetted into a cuvette with a 1 cm light path and reactions were MRT67307 manufacturer initiated by adding the cell extract or substrate respectively. The total protein concentration of the crude cell extract was determined using RotiQuant (Carl Roth GmbH, Karlsruhe, Germany). The overall activity

of 6-phosphogluconate dehydratase (EDD) and 2-dehydro-3-deoxyphosphogluconate aldolase (EDA) was measured using a two-step reaction [30]. For this purpose 0.8 μmol SPTBN5 6-phosphogluconate, 1 μmol MgCl, 5 μmol Tris-HCl buffer (pH 7.65) and 100 μl of extract were incubated in a total volume of 0.5 ml for 5 min at room temperature. The reaction was stopped by dilution with 2 ml of the same buffer and then by heating in a boiling water bath for 2 min. After centrifugation, the supernatant solution was assayed for pyruvate with NADH and lactate dehydrogenase according to Peng and Shimizu [31]. The activity of 6-phosphofructosekinase (PFK) in the crude cell extract was assayed as described by Gancedo and Gancedo [32]. The reaction mix contained 50 mM imidazole HCl (pH 7.0), 0.05 mM ATP, 5 mM MgCl2, 1 mM EDTA, 0.25 mM NADH, 0.