05b-protein_characterizaton

For a molecule, the phosphorescence lifetime without quenching is 1.0 s while with a quencher population of 10-2 M the phosphorescence lifetime is 0.10 s. Calculate the rate constant for phosphorescence assuming that kisc >> (kF + kec + kic). Calculate the rate constant for external conversion of the triplet state (kec’), the quenching rate constant for the triplet state (kq’), and the Stern-Volmer quenching constant. Assume that intersystem crossing from T1 to So is negligible.

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…

In a FRET experiment designed to monitor conformational changes in T4 lysozyme, the fluorescence intensity fluctuates between 5000 and 10,000 counts per second. Assuming that 7500 counts represents a FRET efficiency of 0.6, what is the change in FRET pair separation distance during the reaction? For the tetramethylrhodamine-texas red FRET pair employed ro = 50. Å. Express your answer to two significant figures and include the appropriate units. HÀ ? Ar = Value Units

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,…

The efficiency n of fluorescence resonance energy transfer (FRET) is given by: R + R° A solution is prepared containing linear molecules, each consisting of an anthracene donor and a tryptophyl peptide acceptor separated by n L-prolyl linker units. The solution absorbs 0.230 mJ of laser radiation with a wavelength of 273 nm and emits 1.35 ×10² mJ of fluorescence at a wavelength of 293 nm. Given that R. = 2.20 nm, ø= 0.36 for anthracene, and the approximate length of one linker unit is 0.34 nm, determine n.

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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

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.

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

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 diameter of the methyl radical is about 308 pm. What is the maximum rate constant in the expression d[C2H6]/dt = kr[CH3]2 for second-order recombination of radicals at 298 K? It is reported that 10 per cent of a sample of ethane of volume 1.0 dm3 at 298 K and 100 kPa is dissociated into methyl radicals. What is the minimum time for 90 per cent recombination?