05b-protein_characterizaton

The biuret reaction is a general method for the determination of proteins or peptides. This method is based on the reaction of the Cu2+ with four NH groups of the peptide bonds, forming a violet complex with an absorption maximum at 540 nm. The intensity of the color is proportional to the number of peptide bonds present, and therefore to the amount of protein. This reaction is specific, the dipeptides and amino acids give a negative reaction, and few substances interfere. A quantity of 19.89 g of fish meat is extracted with 100 mL of glacial acetic acid. Subsequently, 3 mL of the previous solution with 3 mL of the biuret reagent to generate the reaction, after 30 minutes. To reduce errors due to other interfering substances and residual turbidity, the corrected absorbance method Ac is applied to 500 nm and 570 nm. In a study, a standard sample analyzed by the Kjeldahl method (total Nitrogen analysis) is obtained, resulting in 0.43% N (w / v), (Protein content [%] =% N x 6.38). 3 mL of…

Trace amounts of rare clements are found within groundwater and are of interest to goochemists. Earopium and terbium are 30 - lanthanide-scries clements that can be measured from the intensity of their fluorescence emittcd when a solution is illuminated with ultraviolet radiation. Certain organic 25 - compounds that bind Eu(III) and Tb(IIl) enhance the cmission, and substances found in natural waters can decrease 20- the cmission. For that reason it is necessary to use standard Eu (II) additions to the sample to correct for such interference. The graph shows the result of such an cxperiment in which the 15- concentration of Eu(III) and Tb(III) was mcasured in a sample of groundwatler. The x-intercept of the Eu(III) plot is 10- -23.1 ml. and the x-intercept of the Th(III) plot is -9.91 ml. In cach case, 10.00 ml. of the sample solution and 15.00 ml. 5- Tb (III) of an organic additive were added to a scries of live 50 ml. volumctric flasks. The standard Eu(lI) or Th(III) solution (0,…

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5. The table shows intensities and lifetime data for luminescence of a ruthenium complex for a range of oxygen concentrations. Concentration Fluorescence Fluorescence intensity oxygen (uM) lifetime (us) 590 1.008 22 574 0.978 44 557 0.964 72 552 0.95 132 518 0.916 174 503 0.893 267 478 0.836 a. Why does the luminescence intensity decrease as the oxygen concentration increases? The luminescence intensity decreases as the oxygen concentration increases because the oxygen is acting as a quencher so when the oxygen is present the luminescence gets excited and then that energy is transferred and accepted by охудen. b. Plot a Stern-Volmer graph based on fluorescence intensity. Is the calibration linear? The calibration is c. Plot a Stern-Volmer graph based on fluorescence lifetime. What type of quenching is indicated by the plot?

The data given below was generated by a student in Bio 240L during a Bradford Assay. A standard curve was generated by preparing a set of standard samples of protein (bovine serum albumin) and adding the dye Coomassie Brilliant Blue, When the protein binds to Coomassie Brilliant Blue it absorbed light at 595 nm with an extinction coefficient of 43,000 M-1 cm-1. After the dye binding reaction was complete, absorbance values for each protein standard solution were measured at 595 nm and recorded. Standard # 1 2 13 4 Concentration of protein binded to Coomassie Brilliant Blue (M) 6.35x10-7 1.23x10-6 3.85x10-6 5.68x10-6 OOO Absorbance at 595 nm 0.093 0.176 0.560 0.813 Prepare a standard curve with the student generated data. What is the slope from the standard curve rounded to four sig figs and no units? 1.4 143398 6.972x10-6 1.434x105

with amine concentration as shown below. A time-resolved laser spectroscopy experiment had also shown that the half-life of the phosphorescence in the absence of quencher is 29 us. What is the value of k,? [Q/(mmol dm) 1.0 5.0 10.0 I/(arbitrary units) 0.41 0.25 0.16 P17G.4 When benzophenone is exposed to ultraviolet radiation it is excited into a singlet state. This singlet changes rapidly into a triplet, which phosphoresces. Triethylamine acts as a quencher for the triplet. In an experiment in the solvent methanol, the phosphorescence intensity varied

Calculate the molar extinction coefficient (e) of a molecule at a particular wavelength given that a 0.000764 M solution of the molecule produced a fluorescence intensity (I) of 1177 when the irradiance of the beam incident to the sample (Po) was 821 and the length of the medium (b) was 1.12 cm. The proportionality constant k' for this molecule is 0.319. € = ×10 TOOLS M-1.cm-1

A 25.0 mL aliquot was taken from a 500.0 mL sample of tonic water containing an unknown amount of quinine and diluted to a volume of 200 mL. At 347.5 nm, the fluorescence intensity of the diluted sample was measured 85.7 an arbitrary scale. Under similar conditions, a 27.5 ppm standard quinine solution had a fluorescence intensity of 185. Calculate the mass of quinine in the original tonic water sample in mg.  Do not include units in your answer.

Why is it reasonable that the Ksp of NiCl2 should be so high? given: NiCl2~~>Ni2+(aq)+2Cl-(aq) ksp=497.504 ksp=[Ni2+][Cl-]^2 [Ni2+]=4.992 [Cl-]=9.983

For an enzyme reaction followed spectrophotometrically at 340 nm the Vmax was calculated at 0.14 ∆A340/min (ε340 = 5.22 mM-1.cm-1). The 1 mL reaction in a 1 cm cuvette contained 30 ng of an enzyme (Mr of 100 000 g/mole). Calculate the Kcat for this enzyme.

Quinine in a 1.553-g antimalarial tablet was dissolved in sufficient 0.10 M HCl to give 250 mL of solution.A 10.00-mL aliquot was then diluted to 50.00 mL with the acid. The fluorescence intensity for the dilutedsample at 347.5 nm provided a reading of 196 on an arbitrary scale. A standard 100-ppm quinine solutionregistered 125 when measured under conditions identical to those for the diluted sample. Calculate the massin milligrams of quinine in the tablet.

There is a class of polyesters that have the general structure shown below. For example, in polyethylene terephthalate (PET) m =1. How would you expect the Tg ad Tm of these polymers to vary with m, given that the molecular weight of the chain is held constant?  Give reasons for your answer. Also, assuming that you are now just considering one member of this class of polymers, say PET, how does the Tg vary with molecular weight, n.

Please don't provide handwritten solution ....

50 uL of an aqueous sample of double-stranded DNA is dissolved in 950uL of water. This diluted solution has a maximal absorbance of 0.326 at 260 nm. What isthe concentration of the original (more concentrated) DNA sample, expressed in ug/ul?  I would like to know the process of this question. And I was wondering as well if the total diluted volume would be 950ul + 50ul = 1000ul

The quenching of tryptophan fluorescence by dissolved O₂ gas was monitored by measuring the emission lifetimes at 348 nm in aqueous solutions. [0₂]/(10-² mol dm-³) T/(10-⁹ s) 0 2.3 5.5 8 10.8 2.6 1.5 0.92 0.71 0.57 A. 0.95 E-2 M B. 4.3 E-2 M C. 1.8 E-2 M D. 3.0 E-2 M E. None of the choices From the data above, predict the value of [0₂] required to decrease the intensity of tryptophan emission to 50% of the unquenched value.

CPU/RAM ProctorU e Proctor e Proctoru o.com/collab/ui/session/join/43918c0bf9cb421ca7b98b0075f5f239 Firefox Ex SPECTROSCOPY 1. If the concentration of solute in a solution is high, the Absorbance will be high or low and why? 2. Was the spectroscopy experiment qualitative or quantitative analysis? 3. If we have 12M HCI and we need 3 L of 1M HCI, how much 12 M should we use? 4. What does Molarity mean? 5. When must safety goggles be worn? 6. If you make a mistake recording data, what must you do? spec hw.pptx (2/3) ..% An

The levels of Vitamin B1 in a sample of milk was determined using the Standard Addition method and technique of fluorescence spectroscopy. 18.0 ml of the milk sample was diluted to 20.0 ml using distilled water and then the fluorescence was measured. The resulting signal was 210 units. A spike was made by taking 18.0 ml of the same milk sample, adding 1.0 ml of a 6.0 ppm Vitamin B1 standard solution, and then diluting to 20.0 ml using distilled water. The signal of the spiked milk was 540 units. Calculate the concentration of Vitamin B1 in the original milk sample (in ppm). Report to 3 decimal places.

You obtained the following raw data when setting up a Bradford standard curve:   BSA (mg/ml) Absorbancy 595nm 0 0.225 1 0.310 2 0.420 3 0.510 4 0.610 5 0.720 6 0.810 7 0.915 8 0.950 9 0.980 10 0.990   After blanking against a bradford-dH2O sample, the protein concentration of an unknown sample was determined using the same method and an absorbancy of 0.523 was obtained. Set up a standard curve, excluding outliers (experimental and statistical) and determine the protein concentration in the unknown sample in mg / ml (up to 3 significant figures).