Glucose - continued utilization

The phosphoglucomutase reaction involves continual utilization and resynthesis of the cofactor, but it cannot cause the net synthesis of glucose-1,6-diphosphate. Two mechanisms have been found to increase the amount of this cofactor in each case glucose-l-phosphate is the phosphate acceptor but the phosphate donors are different for the two enzymes involved. Glucose-l-phosphate kinase requires ATP to carry out the reaction ... 

The rate of mitochondrial oxidations and ATP synthesis is continually adjusted to the needs of the cell (see reviews by Brand and Murphy 1987 Brown, 1992). Physical activity and the nutritional and endocrine states determine which substrates are oxidized by skeletal muscle. Insulin increases the utilization of glucose by promoting its uptake by muscle and by decreasing the availability of free long-chain fatty acids, and of acetoacetate and 3-hydroxybutyrate formed by fatty acid oxidation in the liver, secondary to decreased lipolysis in adipose tissue. Product inhibition of pyruvate dehydrogenase by NADH and acetyl-CoA formed by fatty acid oxidation decreases glucose oxidation in muscle. 

The demand for monitoring common metabolites of diagnostic utility such as glucose, urea and creatinine continue to provide the impetus for a staggering research effort towards more perfect enzyme electrodes. The inherent specificity of an enzyme for a given substrate, coupled with the ability to electrochemically detect many of the products of enzymatic reactions initiated the search for molecule-selective electrodes. 

The clinical utility of electrochemical sensors for continuous glucose monitoring in subcutaneous tissue has been limited by numerous challenges related to sensor component and biocompatibility-based failures.1,2 Sensor component failures include electrical failure, loss of enzyme activity, and membrane degradation,3 4 while examples of biocompatibility-based failures include infection, membrane biofouling (e.g., adsorption of small molecules and proteins to the sensor surface), and bbrous... 

Figure 3 shows a comparison of the glucose consumption among a low-severity (Log R0 = 3.3), medium-severity (Log R0 = 4.2), and high-sever-ity (Log R0 = 5.0) pretreatment with and without carbonic acid. Glucose consumption for different severity hydrolysates was measured at the time when the 0% control hydrolysate had achieved 50% utilization. A trend is shown that the yeast was more inhibited as the severity of the pretreatment increased. Figure 3 also shows a difference between corn stover samples and aspen wood samples for the same pretreatments. Aspen wood was more inhibitory than corn stover for all three pretreatment conditions, and the difference between the two continued to increase as the severity of the pretreatment increased. 

Zeng AP, Deckwer WD (1995b), Mathematical modeling and analysis of glucose and glutamine utilization and regulation in cultures of continuous mammalian cells, Biotechnol. Bioeng. 47 334-346. 

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