Bio135_assignment_2 (incomplete)

Bio135_assignment_2 (incomplete) - Name: Soo-Khee Chia ID...

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Name: Soo-Khee Chia ID #: 005811923 Biol 135 Assignment #2 CALCULATIONS: (8-42) You have isolated the proteins from two adjacent spots after two dimensional polyacrylamide-gel electrophoresis and digested them with trypsin. When the masses of the peptides were measured by MALDI-TOF mass spectrometry, the petides from the two proteins were found to be identical except for one. For this peptide, the mass to charge (m/z) values differed by 79.97, a value that does not correspond to a difference in amino acid sequence. (For example, glutamic acid instead of valine at one position would give an m/z difference of around 30.) Can you suggest a possible difference between the two peptides that might account for the observed m/z differences? The presence of phosphate group on the peptide is the main reason that causing the differences in the m/z value. The substitution of H by PO4 will shift the mass-to-charges ratio (m/z) by 79.97, as oxygen atoms contributes value of 48, phosphorus atom contributes value of
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This note was uploaded on 04/12/2008 for the course BIOL 135 taught by Professor Soto during the Spring '08 term at San Jose State University .

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Bio135_assignment_2 (incomplete) - Name: Soo-Khee Chia ID...

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