A solution of [U 14C] glucose-1-phosphate (specific activity = 16,000 cpm/mmole) was  incubated with glycogen and glycogen phosphorylase, an enzyme which adds glucose units on to  glycogen. Radioactivity was incorporated into the glycogen primer at a rate = 2550 cpm/min. The rate  of the enzymatic reaction in units of mmole glucose incorporated per minute is:  (a) 0.016 mmol/min  (b) 0.57 mmol/min  (c) 0.16 mmol/min  (d) 5.7 mmol/min

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Draw the (B1-->A1) linked dissacharide formed between the C3 epimer of B-D-glucose and the C2 epimer of a-D-galactose. Explain in 1-2 sentences why (or why not) a precipiate would be observed when mixing this dissacharide in an alkaline solution of copper.

If a small amount of [1−14C] glucose is added to an aerobic yeast culture, where will the 14C label initially appear in citrate molecules?

From the complete oxidation of glucose (glucose  →  6CO2), how many total nucleotide triphosphates are yielded (be sure to deduct payback) as part of substrate level phosphorylation?

Draw the enediolate intermediate of the ribulose-5-phosphate isomerasereaction (Ru5P → R5P).

Lactate dehydrogenase is a tetramer of MW 134000 g/mole composed of subunits which are equal in size. It is found in the cytoplasm of eukaryotic and prokaryotic cells. Describe the secondary, tertiary and quaternary structures of lactate dehydrogenase.

The enzyme aspartate transcarbamoylase catalyzes an early step in pyrimidine biosynthesis. The two states of the multi-subunit enzyme are shown below. Note that the binding of the regulatory molecule CTP (cytosine triphosphate) causes the enzyme complex to be inactive. Is this situation an example of positive or negative regulation? Explain why the use of CTP as the regulatory molecule is logical givén the overall function of this particular enzyme. INACTIVE ENZYME: T STATE catalytic subunits regulatory subunits OFF 6 CTP ON ACTIVE ENZYME: R STATE

In some organisms, isoleucine can be synthesized in a multi-step procedure (a series of enzymatic reactions), beginning with a molecule of threonine. Keeping that in mind explain the experimental results below. Amount of endproduct Activity of threonine (isoleucine) deaminase None Low Medium High Very high High Moderate Very low

The enzymatic activity of PFK1 is generally measured by set- ting up a coupled enzyme assay system whereby aldolase, triose phos- phate isomerase, and glycerol-3-phosphate dehydrogenase are added to the assay mixture. For the latter enzyme, NADH is added and its change in concentration is readily monitored at 340 nm. Write the chain of reactions catalyzed by these enzymes using structural formulas, label substrates and products, and explain why the coupled en- zyme assay system leads to oxidation of NADH. While the chain of reac- tions is similar to those in glycolysis, there is a critical difference because of the dehydrogenase enzyme. Describe how this enzyme causes the chain of reactions to differ from those in glycolysis.