SC BIOL 541 - Characterization of Protein (7 pages)

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BIOL 541 1st Edition Lecture 5 Outline of Last Lecture I Chromatography Outline of Current Lecture II Characterization of Protein III Freezing Point Depression IV Mass Spectroscopy Current Lecture Biochemistry Lecture 5 Characterization of Protein The molecular weight as well as the shape of the protein has already been established partially by purification The thermodynamic property of the solution is dependent upon the molecules of the solution independent of their size Freezing point depression This is also based upon vapor pressure and osmotic pressure The concept is that change in 1 86 degrees Celcius molarity is applicable Henceforth after dissolving the unknown in a known volume of liquid the change in increase or decrease in temperature is determined Based on molarity the molecular weight can be determined Disadvantage Since it requires a large amount of protein to be dissolved it becomes expensive These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Dr Svedberg Ultra Centrifugation technique The high speed of protein spinning literally precipitates the protein The instrument has a roller with a window The transparent centrifuge tube is present as well as the optics which measure protein concentration The sample is uniformly distributed since there is a high rate of speed The upper part of the cell clears as the protein passes out The rate of sedimentation time is measured The computer calculates the inflection point which is a derivative of dc dx And points on the graph such as t1 t2 and t3 are picked up Sedimentation velocity is calculated and varies between 1 200 x 10 13 cm s 10 13 cm s is the unit in ultra centrifugation and named Svedberg S after the scientist who discovered it Eukaryotes have ribosomes with values of 40S 60S Molecular weight SRT 1 Vp D Hence large proteins have faster sedimentation Correction Factor Voyancy and simple diffusion both