mahatoanju crisper worksheet 1

Past paper

Enzyme Inhibition Show complete solution and indicate the appropriate units. Answer A to D.

Kk.93.

Do 9(a) as fast as possible

Can you please help explain how to approach these two problems of calculating the turnover number and average time?

Express the initial velocity of α-amylase in terms of substrate disappearance and product (as glucose) formation.

5. An enzyme catalyzes the reaction M concentration of 1 nM, and the Vmax is 2 µM s-1. The Km for substrate M is 4 µM. N. The enzyme is present at a (a) Calculate kcat. (b) What values of Vmax and Km would be observed in the presence of sufficient amounts of an uncompetitive inhibitor to generate an a' of 2.0? Increased or decreased?

Determine the branch points and reducing ends of amylopectin.         A 0.5g sample of amylopectin was analyzed to determine the fraction of the total glucose residues that are branch points in the structure. The sample was methylated and then digested, yielding 50 μmol of 2,3-methylglucose and 0.4 μmol of 1,2,3,6-tetramethyl glucose. (MWglucose = 162 g/mol, minus H2O)  What fraction of the total residues are branch points?  How many reducing ends does the amylopectin have?

Could someone explain what this is saying? I would like a better understanding. FIGURE D CPP32 (Caspase-3) protease activity. Aliquots of cell lysates (50μL) were incubated with an equal volume (50 μL) of the reactionbuffer and 5 μL of 7-amino-4-trifluoromethyl coumarin (AFCDEVD) for 1 hour at 37˚C (Clontech). The shift in fluorescenceemission of AFC-DEVD, on its proteolysis to free AFC by theprotease, was detected in a fluorometer, using a 400 nm excitationfilter and 505 nm emission filter.

Differentiate and explain the chemical basis of the Kjeldahl, Lowry and Bradford techniques that can be used to quantitate proteins in quality control and research.

An enzymatic assay was performed using the enzyme phophofructokinase-1, which catalyses the committed step of the glycolysis pathway. What is the final concentration of the fructose 6-phosphate substrate in a test tube containing the following: 250 µL of 150pM fructose 6-phophate, 100 µL 20 mg.ml-1 phosphofructoskinase-1 and 150 µL 100mM buffer pH 7.5

Some proteases are cysteine proteases and threonine proteases as opposed to serine proteases. What properties of these amino acids residues allow them to be in a similar catalytic process? Cysteine:   R=-CH2SH Threonine: R= -CH(CH3)OH

Dr. Alghe has just performed a restriction digest on DNA she extracted from her samples. She must now run her DNA out on a gel to separate the fragments based on size. To do this she must prepare a 1.2% agarose gel, where the percentage is determined as mass/vol. How many grams of agarose must she add to 200 mL of buffer in order to arrive at the correct percentage?

What could be the possible answers in number #1,2,3?

kcat (sec). 500 A 300 100 80 60 R-Ć- The following kinetic data were obtained for this enzyme: 40 4 H 5 6 COO OH pka: 5.1 and 9.6 7 pH kcat/Km (mM¹ sec) 1000 100 8 9 10 4 B 5 pka: 5.5 and 8.9 6 7 PH R- 8 9 10 KIE (VND) 7 6 5 4 3 نا 2 OH H C 4 5 COO pka 6 - 9.4 7 8 PH 9 10 (i) Draw a scheme showing all the protonation states of E (depicted as E, ES, ESH, EH, EH2, etc.) and their equilibria, together with the actual conversion of S (substrate) into P (product), assuming a single intermediate (you do not have to put in the rate or equilibrium constants). (ii) Match up the 4 pKas in the figures, A and B, with the different protonation states. (Explain what the pKas in Figures A and B represent). (iii) The data in Figure C refers to the kinetic isotope effect on the keat, obtained when the H indicated in red in the reaction given above, is replaced with a deuterium. Why does Figure C show only one pka? Given the information in C, together with that of A and B, what can you conclude about…

Many peptides react further after synthesis (process is called post-translational modification). In this example a cysteine cyclizes to form a thiazole ring in Sanguinamide A. O= HN HN" SH -H₂O o= HN" 0= 0= N₂ S HN Sanguinamide A

The catalytic activity of an enzyme is being measured at pH 7.5 and requires that the side chain of a specific Cys (C) residue be in its unprotonated (conjugate base) form for the enzyme to be active. That specific Cys side chain in the protein has a pKa of 7.8. a) For this Cys side chain with a pKa of 7.8, what is the base/acid ratio at pH 7.5? b) What fraction of the total enzyme molecules in a solution of the enzyme at pH 7.5 have that Cys side chain in the active form? (Express the answer as a %) c) The name of the Cys side chain functional group is? d) The active form of the Cys side chain in this enzyme would be? i. positively (+) charged ii. uncharged (neutral) iii. negatively (–) charged

I am not sure how to do number 10

5. Draw a schematic illustrating the overall iteration process for solid phase peptide synthesis. You do not need to use specific chemical structures, but your overall depiction should be clear.

Most of the ultraviolet absorption of proteins at 280 nm is due to their content of a. Glutamate b. Tryptophan c. Alanine d. Aspartate

X 10 (select) v molecules of penicillin

1. An enzyme-catalyzed reaction has a KM of 1 mM and a Vmax of 5 nM s-1. What is the reaction velocity when the substrate concentration is 0.25 mM? 2. If an enzyme-catalyzed reaction has a velocity of 2 mm/min and a Vmax of 10 mm/min when the substrate concentration is 0.5 mM, what is the KM?

Please answer the calculation