Imаge Descriptiоn Lаctаte dehydrоgenase interactiоn diagram showing the enzyme binding to pyruvate and NADH. The image details amino acid residues such as Arg109, Gln102, Thr246, His195, Arg171, and Asp168, involved in the binding process. Pyruvate is positioned centrally, with NADH on the right. Key interactions are depicted, illustrating the molecular structure and connections within the enzyme’s active site. The diagram above is of the active site of lactate dehydrogenase. This enzyme reduces the ketone in pyruvate (2-oxo-propanoate) to an alcohol in lactate. Pyruvate is shown bound to the active site of the enzyme. When Arg 109 is replaced with Gln, the enzyme binds pyruvate only 5% as well and the overall activity of the enzyme drops to 0.07% of what it was. Referring to the above diagram, briefly explain why this is the case. (2 pts.) When Arg 171 is replaced with Lys, the overall enzymatic activity drops to 0.05% of what it was. Briefly explain why this structural change results in such a dramatic drop in activity. (2 pts.) If Gln 102 is replaced by Arg, the enzyme will accept oxaloacetate (it is the structure of pyruvate with a carboxylate group i.e. carboxylic acid group attached to the methyl group of pyruvate) instead of pyruvate as substrate. Explain why this amino acid change accommodates the binding of oxaloacetate. (2 pts.) This diagram left off the NAD+ carboxamide side chain on the ring. Knowing that the side chain is present, would NAD+ have a binding preference toward the Thr 246, the Ile 250, or no preference? Justify your answer. (2 pts.) Draw and describe the structure of the expected pyruvate transition state intermediate for this reaction. (3 pts.)
Electrоn Trаnspоrt Chаin аnd Oxidative Phоsphorylation (1–12) Select the missing compound, cofactor, name, element, or ion for each of the circles numbered 1–12 on this diagram of the electron transport chain. Some terms may be used more than once, and some terms will not be used at all. Every question has exactly one correct answer. Image Description A detailed diagram of oxidative phosphorylation depicting the electron transport chain within the inner mitochondrial membrane. The diagram shows complexes I, II, III, and IV, along with ATP synthase, highlighting the flow of electrons through various carriers like NADH and FADH2. Protons (H+) are pumped into the intermembrane space, creating a gradient. The movement of electrons is coupled with the synthesis of ATP from ADP and inorganic phosphate by ATP synthase, illustrating the overall process of ATP generation. Answer Options A. AMP I. CuA Q. FAD Y. 4H+ B ADP J. Cyto A R. FADH• Z. H2O C. ATP K. Cyto C S. FADH2 AA. O2 D. ATP Synthase L. Cyto C1 T. FMN BB. 1/2O2 E. Complex I M. Cyto Bh U. FMNH• CC. Q- F. Complex II N. Cyto BL V. FMNH2 DD. QH G. Complex III O. Fe2+ W. H+ EE. QH2 H. Complex IV P. Fe3+ X. 2H+ [Part1] [Part2] [Part3] [Part4] [Part5] [Part6] [Part7] [Part8] [Part9] [Part10] [Part11] [Part12]
Type the cоrrect letter cоrrespоnding to аnswer options in the dropdown below. Molecule Nаme: [nаmes7] Enzyme or Reaction: [reactions7] Image Description This molecule consists of a carbon and nitrogen chain attached to a large coenzyme structure. The terminal end of the chain is a thiol (SH) group. The thiol is attached to ethanol, with an amide on the other end. The amide continues into another ethanol followed by another amide. Beyond the second amide is a propane with an attached alcohol group and two methyl groups. At the far end of the propane is the coenzyme structure. The coenzyme structure comprises an adenosine diphosphate (ADP) moiety, which includes a nitrogenous base linked to a ribose sugar and two phosphate groups. There is an additional phosphate group attached to carbon 3 of the ribose sugar. The carbon-nitrogen chain connects to the coenzyme structure via a phosphoester bond. Image By: NEUROtiker. (2007). Structure of coenzyme A (figure). Wikimedia Commons (public domain). Answer Options Molecule Names Enzymes and Reactions A. Acetyl CoA L. Alcohol dehydrogenase B. ADP M. Alpha ketoglutarate dehydrogenase complex C. ATP N. Citrate synthase D. Coenzyme A O. Hexokinase E. FAD P. Isocitrate dehydrogenase F. FADH2 Q. Phosphofructokinase 1 G. Lipoic acid R. Phosphoglycerate kinase H. Magnesium S. Pyruvate decarboxylase I. NAD+ T. Pyruvate dehydrogenase complex J. NADH U. Succinyl CoA synthetase K. TPP V. Succinate dehydrogenase