Lactate production, specific rate

Typical kinetic profiles (hybridoma). (A) Cell concentration and viability (B) glucose consumption (GLC) and lactate production (LAC) (C) monoclonal antibody production (mAb) (D) glutamine consumption (GLN) and ammonium production (NH4+) (E) specific growth rate (px) (F) alanine (ALA) and glycine (GLY) production. Adapted from Lee (2003). Symbols correspond to the experimental data and the lines to the manual curve fitting. Vertical lines indicate the instant at which exponential growth phase ended (gx < Px.max)-... 

Figure 42.7 Metabolic quotients for the glucose step change experiment described in Figure 4.2.5. (a) Specific glucose consumption rate (mmol glucose consumed viable celL da>r ) as a function of culture time, (b) Specific lactate production rate (mmol lactate produced viable celH day" ) as a function of culture time. Adapted from Miller et al (1989) by permission of Biotechnology and Bioengineering.

For most cell lines it is found to increase with the specific growth rate. Thus the specific rates of lactate production can be expressed as a function of p by Equation 4.3.4, which contains two parameters the non-growth-associated specific lactate production rate, mLac (mmol lactate 10 cells h ), and the lactate to biomass stoichiometric yield, (mmol lactate 10 cells). A similar expression is often applicable to the specific rate of ammonia production (Equation 4.3.6) and antibody secretion (Equation 4.3.7). 

Calculate the specific rate of metabolites and antibody production The specific rate of lactate production ... 

Linear relationships are also apphcable to the specific rates of lactate, ammonia and antibody production ... 

Specific lactate production rate (mmol 10" cells h" )... 

The initial rate equation is again of the form of Eq. (1) with the kinetic coefficients as in Table I, which shows that the mechanism differs from the simple ordered mechanism in three important respects. First, the isomerization steps are potentially rate-limiting evidence for such a rate-limiting step not attributable to product dissociation or the hydride-transfer step (fc) has been put forward for pig heart lactate dehydrogenase 25). Second, Eqs. (5) and (6) no longer apply in each case the function of kinetic coefficients will be smaller than the individual velocity constant (Table I). Third, because < ab/ a< b is smaller than it may also be smaller than the maximum specific rate of the reverse reaction that is, one of the maximum rate relations in Eq. (7) need not hold 26). This mechanism was in fact first suggested to account for anomalous maximum rate relations obtained with dehydrogenases for which there was other evidence for an ordered mechanism 27-29). 

The specific ATP production rate can be estimated by assuming that all ATP comes from glycolysis or oxidative phosphorylation. As a first approximation, it can be assumed that all lactate produced comes from glycolysis and that all oxygen consumed is utilized for oxidative phosphorylation. Therefore, there will be one mole of ATP produced per mole of lactate produced. Also, depending on the P/O ratio (ATP molecules formed per O atom consumed), there will be 6 moles (for P/O = 3) or 4 moles (for P/O = 2) of ATP produced per mole of Oj consumed. Thus the specific ATP production rate can be expressed as ... 

Figure 4.3.2 Evolution with time of the specific growth and death rates (a), the specific consumption rates of glucose (b) and glutamine (c) and the specific production rates of lactate (b), ammonia (c) and monoclonal antibodies (d) in VO 208 batch culture (data from Figure 4.3.1).

Figure 4.3.3 Relationships between specific glucose (a) and glutamine (c) consumption rates, lactate (b), ammonia (d) and monoclonal antibody (e) production rates and specific growth rate during lag and growth phases of VO 208 batch culture.

In order to enhance affinity and selectivity for Brc-Abl, we modified the inhibitor methylating at positions I and II (Fig. 7.5d). The synthesis of the wrapping prototype recapitulates imatinib synthesis [38], as described in [39], To test whether the specificity and affinity for Brc-Abl improved, we conducted a spectrophotometric kinetic assay to measure the phosphorylation rate of peptide substrates in the presence of the kinase inhibitor at different concentrations. This assay couples production of adenosine diphosphate (ADP), the byproduct of downstream phosphorylation, with the concurrent detectable oxidation of reduced nicotinamide adenosine dinucleotide (NADH). The oxidation results upon transfer of phosphate from PEP (phospho-enolpyruvate) to ADP followed by the NADH-mediated reduction of PEP to lactate. Thus, phosphorylation activity is monitored by the decrease in 340 nm absorbance due to the oxidative conversion NADH->-NAD+ [34, 39]. 

For example, when a heart attack occurs, a lack of blood supplied to the heart muscle causes some of the heart muscle cells to die. These cells release their contents, including their enzymes, into the bloodstream. Simple tests can be done to measure the amounts of certain enzymes in the blood. Such tests, called enzyme assays, are very precise and specific because they are based on the specificity of the enzyme-substrate complex. If you wish to test for the enzyme lactate dehydrogenase (LDH), you need only to add the appropriate substrate, in this case pyruvate and NADH. The reaction that occurs is the oxidation of NADH to NAD+ and the reduction of pyruvate to lactate. To measure the rate of the chemical reaction, one can measure the disappearance of the substrate or the accumulation of one of the products. In the case of LDH, spectrophotometric methods (based on the light-absorbing properties of a substrate or product) are available to measure the rate of production of NAD+. The choice of substrate determines what enz)rme activity is to be measured. 

Resting cells of a recombinant K. pneumoniae J2B strain that overexpresses an aldehyde dehydrogenase (KGSADH) were utilized for coproduction of 3-HP and 1,3-pro-panediol (PDO) from glycerol. The fed-batch bioconversion was performed under anaerobic conditions in a 1.5 L bioreactor with l.Og CDW/L at a constant pH of 7.0 and resulted in 125.6mM 3-HP and 209.5 mM PDO after 12 h with a cumulative overall productivity, yield, and maximum specific production rate of 27.9mmol/Lh, 0.71 (mol/mol), and 128.5mmol/g CDW/h, respectively.The major by-products were lactate, succinate, and 2,3-butanediol. °... 

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