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Answer final question please
Case 20 NAD-dependent Glyceraldehyde-3-phosphate Dehydrogenase from Thermoproteus tenax Focus concept Glycolytic enzymes from Thermoproteus tenar are regulated in an unusual manner. Prerequisites The glycolytic pathway .Enzyme kinetics and inhibition. The cooperative nature of regulated enzymes. Background ism rium Thermoproteus tenax is rather peculiar compared to the types of organisms usually studied in introductory biochemistry For example, the phosphofructokinase reaction in T. tenax is reversible, and is dependent upon pyrophosphate rather than ATP. In addition, T tenax has two different glyceraldehyde-3- phosphate dehydrogenase (GAPDH) isoenzymes. One is well known and, although it requires NADP as a cofactor instead of NAD, it resembles the GAPDH enzyme found in E. coli and is referred to as the phosphorylating GAPDHT. In contrast, the second isoenzyme is irreversible and requires NAD as a cofactor and is referred to as the nonphosphorylating GAPDH. In this case, we will consider the properties of the latter enzyme. The balanced equation of the reaction catalyzed by the nonphosphorylating NAD-dependent glyceraldehyde-3-phosphate dehydrogenase is shown below.
+ NAD T. tenax -OH + NADH+H Glyceraldehyde-3-phosphate 3-phosphoglycerate Figure 20.1: Non-phosphorylating NAD-dependent GAPDH in T. tenax. T. tenar stores energy in the form of glycogen, which is degraded to glucose-1-phosphate. The glucose-1-phosphate is then converted to glucose-6-phosphate and then enters the glycolytic pathway. The two GAPDH enzymes are probably differently regulated in T. tenax. The authors of this study propose that phosphorylating, NADP-dependent GAPDH is involved in efficient ATP production whereas the non-phosphorylating, NAD -dependent GAPDH is somewhat involved in ATP production but is also involved in providing intermediates for cellular The gene for the non-phosphorylating, NAD-dependent GAPDH was cloned and sequenced and its kinetic characteristics were studied. Summary information is presented in Table 1.1. NAD saturation Without AMP V units/mg Ku., mM 36.5 3.3 With AMP Vnss, units/mg Ku, mM 37.0 1.4 Subunit (kD) Native (kD) 55,000 220,000
What is the ATP yield for one mole of glucose oxidized by the pathway nonphosphorylating GAPDH enzyme (entrance of glucose-1-phosphate to glycolysis c not require ATP. Neither does T: tenax PFK)? Show used). that uses the your work (where ATP is made and .(1998)J Biol Chem 273, pp.6149-615 Reference Brunner, N. A, Brinkmann, H, Siebers, B, and Hensel, R
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