The enzyme urease increases the rate of urea hydrolysis at pH 8.0 and 20 \deg C by a factor of 1014. Suppose that a given quantity of urease can completely hydrolyze a given quantity of urea in 15 minutes at pH 8.0 and 20º C. How long would it take for this amount of urea to be hydrolyzed in the absence of urease at the same temperature and pH in sterile conditions? time = uncatalyzed year

Carbonic anhydrase facilitates the dissolution of carbon dioxide gas into water by catalyzing its hydration. Is the catalyzed reaction efficient? By what criterion do you state that?

The isoelectric point, pl, of the protein trypsin is 10.5, while that of glyceraldehyde-3-phosphate dehydrogenase is 6.55. What is the net charge of trypsin at pH 5.1 ?[ What is the net charge of glyceraldehyde-3-phosphate dehydrogenase at pH 6.1 ?[ The isoelectric point of glutamic acid is 3.22; asparagine, 5.41. During paper electrophoresis at pH 6, toward which electrode does glutamic acid migrate? | During paper electrophoresis at pH 6.5, toward which electrode does asparagine migrate? [

Oxaloacetate is an inhibitor of succinate dehydrogenase because it is structurally very similar to succinate as shown below. Also, its binding to the enzyme does not involve any covalent bond formation. What type of inhibitor is oxaloacetate? COO | CH₂ 1 CH₂ 1 COO Succinate COO | CH₂ C=O COO Oxaloacetate O a noncompetitive inhibitor both a noncompetitive and an irreversible inhibitor O an irreversible inhibitor O a competitive inhibitor

The enzyme d-amino acid oxidase has avery high turnover number because the d-amino acids are potentially toxic. The KM for the enzyme is in the range of 1 to2 mM for the aromatic amino acids and in the range of 15 to20 mM for such amino acids as serine, alanine, and the acidicamino acids. Which of these amino acids are the preferred substrates for the enzyme?

Proteins are thermodynamically unstable molecules since the Delta G of hydrolysis is quite negative. However, most proteins are not degraded unless they come into contact with proteases in cells. What is the reasoning for this paradox? The reaction is endergonic and will not proceed without energy. There is very little water inside cells to react with protein molecules. The free energy change doesn't reveal anything about the rate of the reaction. The concentration of proteins are low which allows them to be more stable.

The hydrolysis of pyrophosphate to orthophosphate drives biosynthetic reactions such as DNA synthesis. In Escherichia coli, a pyrophosphatase catalyzes this hydrolytic reaction. The pyrophosphatase has a mass of 120 kDa and consists of six identical subunits. A unit of activity for this enzyme, U, is the amount of enzyme that hydrolyzes 10 umol of pyrophosphate in 15 minutes. The purified enzyme has a Vnax of 2800 U per milligram of enzyme. When (S] >> KM, how many micromoles of substrate can 1 mg of enzyme hydrolyze per second? Vnax = umol -s. mg- If cach enzyme subunit has one active site, how many micromoles of active sites, or (E]r, are there in 1 mg of enzyme? (Er = umol - mg-

If an enzyme-catalyzed reaction has a high rate at low pH and low rate at higher pH, this implies that a group on either the enzyme or the substrate must be for an efficient reaction. leaving group oxidoreductase coenzymes O protonated deprotonated The compound that consists of deoxyribose linked by an N-glycosidic bond to N-9 of guanine is: adenylate deoxyguanosine guanosine nucleotide guanylate

Chorismate mutase is an enzyme that promotes a pericyclic reaction by forcing the substrate to assume the conformation needed for the reaction. The product of the pericyclic reaction is prephenate that is subsequently converted into the amino acids phenylalanine and tyrosine. What kind of a pericyclic reaction does chorismate mutase catalyze?

H₂N Combination of two or more protein units 7. Which type of cross-link involves interactions between two cysteine amino acids? 8. Which type of cross-link would form between the following amino acids? Η Ο || H₂N-C-C-OH T CH₂ C=O NH₂ Η Ο LL H₂N-C-C-OH T CH₂ OH 9. To what main enzyme class do the nzym that catalyze the following reaction belong? (oxidoreductases, transferases, hydrolases, lyases, isomerases, ligases) HO | || I c-c-N-C-COO + H₂O IT HR₂ R₁ H 1 This bond is cleaved H H₂N-C-COOⓇ I R₂ Wilter navy q H I H₂N-C-C00 1 R₁ •Qisulfide 10. Briefly explain the Lock and Key enzyme model.