3. In your textbook the termi- nal enzyme catalyzing the ter- minal step of glycolysis is known as pyruvate kinase (PK). No indication is given that in mammalian tissues there are four different iso- forms of this enzyme. The four mammalian isoforms are known as PKL, PKR, PKM1 and PKM2. PKL is expressed in the liver, and PKR is ex- pressed in red blood cells. PKM1 and PKM2 are derived from altemative splicing of the PKM gene. PKM1 is a constitu- tively active isoform expressed Active Site A PKM2 Monomer B Fructose-1,6-Bisphosphate N Phe, Ala, Ser Binding Site PKM2 Tetramer "Activator" Binding Site in differentiated cells from various tissues. In contrast, PKM2 has low basal activity and is activated by an effector molecule fructose 1,6-bisphosphate (FBP). PKM2 is expressed in most proliferating cells. In addition, the regulation of PKM2 pyruvate kinase activity plays an essential role in cancer metabolism and is crucial for the growth and survival of cancer cells. Recently, PKM2 has been reported to function also as a nuclear protein kinase to regulate gene transcription and promote tumorigenesis. The diagram on the right illustrates the quaternary structure of the PKM2 tetramer and the binding sites of metabolic effector molecules. (a) In the laboratory, the catalytic activity of pyruvate kinase is measured by a continuous assay coupled to lactate dehy-drogenase because the reaction products of the PK reac- tion have no suitable absorption or fluorescence properties, in contrast to the properties of NADH and NAD*, as shown in the diagram on the right. Write both reactions with structural for- mulas as a coupled system naming all metabolites, cofactors, and enzymes. Under what conditions in the cell do these reac- tions occur and why is this important for continued turnover of glycolysis? Optical density NADH NAD+ wavelength (nm) Question #3, continued: (b) The diagram on the right illustrates Michaelis plots of wild type yeast pyruvate kinase and of a T403E mutant. The mutation hinders the binding of fructose-1,6-bisphosphate. The table below summarizes steady-state kinetic data of both the wild type and mutant pyruvate kinase in the absence and presence of 1 mM F-1,6-BPi. In the chart below, indicate which enzyme species in the Michaelis plots correspond to the indicated symbols. Base your answers on kinetic data in the table. Wild Type Kd (μM) no effector molecule F-1,6-BPi Kd (PEP) (μM) 1150 ΠΗ Kd (µM) T403E Kd (PEP) (μM) ΠΗ 3.7 960 2.7 10 50 1.0 >5400 830 2.6 1.00 0.80 Relative Velocity 0.40 €0.60 0.20 0.00 500 1000 1500 [PEP] μM 2000 2500 300 Indicate below corresponding wt enzyme or mutant with or without effector molecule × +

5. (a) Hexokinase IV is known as glucokinase (GCK) and is a central metabolic enzyme that participates in glucose homeostatic maintenance by governing the rates of glucose catabolism in pan- creatic B-cells and glycogen storage in hepatocytes (liver cells). In contrast to the regulatory mecha- nisms of hexokinase I or Il in other tissues, GCk is regulated by binding to the Glucokinase Regulatory Protein (GRP) located in the cell nucleus. When glucose in hepatocytes is low, GCK is sequestered in the nucleus by binding to the GRP. High glucose, for instance, after ingestion of a meal, disrupts the GRP-GCK complex, allowing the GCK to diffuse into the cytoplasm to convert glucose into glucose-6- phosphate. Contrast the properties of hexokinases I and IV with respect to oligomeric structure, mech- anism of regulation of their activity, KM value, and dependence of catalytic activity on cellular location. Hexokinase l is found in, for instance, muscle tissue. Property subunit structutre…

In the normal cycle of Ras activity, when Ras is bound to y activity that removes a phosphate to convert GTP back to GDP and this it is inactive. Activation of Ras involves exchanging GDP for The Ras protein has intrinsic Ras. inactivates activates ATP GTP «< Questic A Moving to another question will save this response. ADP GDP GTPase Clo nuclease

3. In your textbook the termi- nal enzyme catalyzing the ter- minal step of glycolysis is known as pyruvate kinase (PK). No indication is given that in mammalian tissues there are four different iso- forms of this enzyme. The four mammalian isoforms are known as PKL, PKR, PKM1 and PKM2. PKL is expressed in the liver, and PKR is ex- pressed in red blood cells. C PKM1 and PKM2 are derived from altemative splicing of the PKM gene. PKM1 is a constitu- tively active isoform expressed Active Site A PKM2 Monomer B Fructose-1,6-Bisphosphate N Phe, Ala, Ser Binding Site PKM2 Tetramer "Activator" Binding Site in differentiated cells from various tissues. In contrast, PKM2 has low basal activity and is activated by an effector molecule fructose 1,6-bisphosphate (FBP). PKM2 is expressed in most proliferating cells. In addition, the regulation of PKM2 pyruvate kinase activity plays an essential role in cancer metabolism and is crucial for the growth and survival of cancer cells. Recently, PKM2 has…

Which of the following best describes the use of 2-deoxyglucose in allowing for cancer therapy? Elevates p53 levels directly to regulate glycolytic flux Blocks activation of HIF1transcriptional activation Diminishes lactate production by inhibiting lactate dehydrogenase to allow increased levels of pyruvate to force the transport of pyruvate into the matrix and the function of the TCA cycle Diminishes lactate export from the cell to allow increased levels of pyruvate to force the transport of pyruvate into the matrix and the function of the TCA cycle Competes with glucose for hexokinase, allowing inhibition of glycolytic flux, reducing ATP production.

16c

select the BEST answer Aconitase is most interesting in that it: Can be coded for by 2 different genes O Exists as either a membrane bound or soluble protein depending on intracellular conditions O Has 2 distinct roles depending on the availability of Iron O Can change the AGº' of it's reaction O Is itself an allosteric regulator of the PDH complex

6. A. List all of the ionizable functional groups that are found in insulin when in aqueous solution. List which amino acid residues have these ionizable groups and list all of the pka and pKb values (including the R groups) that are on both polypeptide chains that make up insulin. (see the table at the end of this HW set; note that tyrosine and cysteine both have unusual pka's, since these side groups ionize above the pKR's given to have a negative charge). B. The isoelectric point of insulin is reported to be around 5.3-5.35. Using the method covered in class, estimate the isoelectric point of insulin and compare your answer to the values above. C. For a polypeptide to be soluble in an aqueous solution, is it good to be near the isoelectric point? Why or why not? Notes: a couple of unusual R group's that ionize (cysteine and tyrosine have R groups that have pka values; histidine has a pkb). The table at the end of this homework set (also in the lecture notes) lists the pka's and…

Most of the GLP-1 receptor structure form part of the transmembrane domain (TMD) that is embedded in the plasma membrane. The TMD enables the transmission of signal induced by the binding of GLP-1 from outside the cell into the cytoplasm of the cell, which in turn initiates a signaling cascade that ultimately leads to insulin secretion. Is the TMD of the receptor mainly hydrophobic or hydrophilic? Explain your answer in 1 – 3 sentences.

Please answer both, thank you