Chapter 5: Q20P (page 128)
Draw a different phylogenetic tree based on the data in Problem 19.
Short Answer
The required phylogenetic tree is:
Problem presents data in a variety of ways.
Chapter 5: Q20P (page 128)
Draw a different phylogenetic tree based on the data in Problem 19.
The required phylogenetic tree is:
Problem presents data in a variety of ways.
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Get started for freeElectrospray ionization mass spectrometry (ESI-MS) of proteins involves creating positively charged ions of the protein and separating them according to their mass-to-charge ratio (m/z).
(a) What causes the different positive charges on different particles of the protein?
(b) The amino acid composition (in numbers of residues per chain) of hen egg-white lysozyme (HEWL) is as follows:
P 2 Y 3 N 14 H 1
D 7 M 2 L 8 E 2
C 8 R 11 G 12 F 3
A 12 I 6 K 6 V 6
S 10 W 6 T 7 Q 3
What is the maximum positive charge that can be present on a HEWL ion?
Question: Purification tables are often used to keep track of the yield and purification of a protein. The specific activity is a ratio of the amount of the protein of interest, in this case Mb, obtained at a given step (ฮผmol or enzyme units) divided by the amount (mg) of total protein. The yield is the ratio of the amount of the protein of interest obtained at a given step (ฮผmol or enzyme units) divided by the original amount present in the crude extract, often converted to percent yield by multiplying by 100. The fold purification is the ratio of the specific activity of the purified protein to that of the crude preparation.
(a) For the purification table below, calculate the specific activity, % yield, and fold purification for the empty cells.
(b) Which stepโDEAE or affinity chromatographyโcauses the greatest loss of Mb?
(c) Which step causes the greater purification of Mb?
(d) If you wanted to use only one purification step, which technique would you choose?
Separate cleavage reactions of a polypeptide by CNBr and chymotrypsin yield fragments with the following amino acid sequences. What is the sequence of the intact polypeptide?
CNBr treatment
1. ArgโAlaโTyrโGlyโAsn
2. LeuโPheโMet
3. AspโMet
Chymotrypsin
4. MetโArgโAlaโTyr
5. AspโMetโLeuโPhe
6. GlyโAsn
You wish to determine the sequence of a short peptide. Cleavage with trypsin yields three smaller peptides with the sequences LeuโGlu, GlyโTyrโ AsnโArg, and GlnโAlaโPheโValโLys. Cleavage with chymotrypsin yields three peptides with the sequences GlnโAlaโPhe, AsnโArgโLeuโGlu, and ValโLysโGlyโTyr. What is the sequence of the intact peptide?
Electrospray ionization mass spectrometry (ESI-MS) of proteins involves creating positively charged ions of the protein and separating them according to their mass-to-charge ratio (m/z).
(a) What causes the different positive charges on different particles of the protein?
(b) The amino acid composition (in numbers of residues per chain) of hen egg-white lysozyme (HEWL) is as follows:
P 2 Y 3 N 14 H 1
D 7 M 2 L 8 E 2
C 8 R 11 G 12 F 3
A 12 I 6 K 6 V 6
S 10 W 6 T 7 Q 3
What is the maximum positive charge that can be present on a HEWL ion?
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