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SEMINARS!!!! Newborn Screening for Enzyme Deficiency Diseases: From Bench to Practice Michael Gelb, UW F 3:15 pm. SL 140. BE THERE!

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Presentation on theme: "SEMINARS!!!! Newborn Screening for Enzyme Deficiency Diseases: From Bench to Practice Michael Gelb, UW F 3:15 pm. SL 140. BE THERE!"— Presentation transcript:

1 SEMINARS!!!! Newborn Screening for Enzyme Deficiency Diseases: From Bench to Practice Michael Gelb, UW F 3:15 pm. SL 140. BE THERE!

2 PPP Song

3 Lyrics http://books.google.com/books?id=oq9EN yL_d9YC&lpg=PP1&pg=PA1#v=onepage &q&f=false

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6 LEHNINGER PRINCIPLES OF BIOCHEMISTRY Fifth Edition David L. Nelson and Michael M. Cox © 2008 W. H. Freeman and Company CHAPTER 15 Principles of Metabolic Regulation

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10 Regulation of Enzyme Activity often occurs by phosphorylation

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13 Role of AMP-activated protein kinase (AMPK) in carbohydrate and fat metabolism. AMPK is activated by elevated [AMP] or decreased [ATP], by exercise, by the sympathetic nervous system, or by peptide hormones produced in adipose tissue (leptin and adiponectin). When activated, AMPK phosphorylates target proteins and shifts metabolism away from energy-consuming processes; shifts metabolism in extrahepatic tissues to the use of fatty acids as a fuel; and triggers gluconeogenesis in the liver to provide glucose for the brain. In the hypothalamus, AMPK stimulates feeding behavior to provide more dietary fuel.

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16 Insulin’s effects on transport and hexokinase activity, not the change in glycogen synthase activity, increase the flux toward glycogen synthesis.

17 Describe these differences! When blood glucose rises above 5 mM, hexokinase IV activity increases, but hexokinase I is already operating near Vmax and cannot respond to an increase in glucose concentration.

18 The protein inhibitor of hexokinase IV is a nuclear binding protein that draws hexokinase IV into the nucleus when the fructose 6-phosphate concentration in liver is high, and releases it to the cytosol when the glucose concentration is high.

19 FIGURE 15-14a Phosphofructokinase-1 (PFK-1) and its regulation. Ribbon diagram of E. coli PFK-1, showing two of its four identical subunits (PDB ID 1PFK). Each subunit has its own catalytic site, where the products ADP and fructose 1,6-bisphosphate are almost in contact, and its own binding sites for the allosteric regulator ADP (blue), located at the interface between subunits.

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24 Fructose 2,6-bisphosphate (F26BP) has opposite effects on the enzymatic activities of phosphofructokinase-1 and fructose 1,6-bisphosphatase. (a) PFK-1 activity in the absence of F26BP is half-maximal when the concentration of fructose 6-phosphate is 2 mM. When 0.13 μM F26BP is present, the K0.5 for fructose 6-phosphate is only 0.08 mM. (b) FBPase-1 activity is inhibited by as little as 1 μM F26BP and is strongly inhibited by 25 μM. In the absence of this inhibitor the K0.5 for fructose 1,6- bisphosphate is 5 μM, but in the presence of 25 μM F26BP the K0.5 is >70 μM. Fructose 2,6-bisphosphate also makes FBPase-1 more sensitive to inhibition by another allosteric regulator, AMP.

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26 Both enzyme activities are part of the same polypeptide chain, and they are reciprocally regulated by insulin and glucagon.

27 Phosphoprotein phosphatase

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31 The PEP carboxykinase promoter region, showing the complexity of regulatory input to this gene.

32 Glycogen granules in a hepatocyte

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41 Glycogenin structure. Muscle glycogenin (Mr 37,000) forms dimers in solution. The substrate, UDP-glucose, is bound to a Rossmann fold near the amino terminus and is some distance from the Tyr194 residues—15 Å from the Tyr in the same monomer, 12 Å from the Tyr in the dimeric partner. Each UDP-glucose is bound through its phosphates to a Mn2+ ion that is essential to catalysis. Mn2+ is believed to function as an electron-pair acceptor to stabilize the leaving group, UDP. The glycosidic bond in the product has the same configuration about the C-1 of glucose as the substrate UDP-glucose, suggesting that the transfer of glucose from UDP to Tyr194 occurs in two steps. The first step is probably a nucleophilic attack by Asp162, forming a temporary intermediate with inverted configuration. A second nucleophilic attack by Tyr194 then restores the starting configuration

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56 “Alfonse, Biochemistry makes my head hurt!!” \


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