Showing posts with label peptide. Show all posts
Showing posts with label peptide. Show all posts

Saturday, 10 May 2014

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What are the ways to store a membrane proteins after extraction?

Experiment involving membrane proteins are quite messy as storage is a major problem for these kinds of proteins 

Membrane proteins and they aren't amenable to freeze thaws even when we add glycerol. The proteins are solubilized in detergent above the cmc so they should be in micelle form in solution. In most case  the protein  are being held at 4C. Is there any other analytical technique to store these membrane proteins.As freezing would possibly degrade the extracted protein sample.



. One of the ways could be  aliquot  the  samples and snap freeze them in liquid nitrogen and store in -80 degree. if its a membrane protein that  are using the cell based system since if it was E. coli then one could have  just had your protein expressed through IPTG and just washed the  cell pellet in STE buffer and spun it down hard and stored the pellet at -20 degree. The use of Na azide is a effective method too .

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Tuesday, 25 February 2014

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Calculate Km and Vmax for phenylalanine-containing peptide is catalyzed by a alpha-chymotrypsin with the following results

The hydrolysis of a phenylalanine-containing peptide is catalyzed by a alpha-chymotrypsin with the following results. Calculate Km and Vmax for the reaction.
Peptide concentration Velocity
2.5 x 10^-4 2.2 x 10 ^ -6
5.0 x 10 ^ -4 5.8 x 10 ^ -6
10.0 x 10 ^ -4 5.9 x 10 ^ -6
15.0 x 10 ^ -4 7.1 x 10 ^ -6


Original data
[S][V]
2.52.2
55.8
105.9
157.1
1/[S]1/[V]
0.40.4545454545
0.20.1724137931
0.10.1694915254
0.06666666670.14084507

Y=1/vmax =0.0554595078
Vmax=18.0311733672


slope = Km/Vmax=0.9332058421
km=slope*vmax=16.8267963262


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