- The peptide Leu?Cys?Arg?Ser?Gln?Met is subjected to Edman degradation. In the first cycle the peptide first reacts with phenylisothiocyanate under basic conditions. The product of this reaction is incubated with anhydrous trifluoroacetic acid and subsequently with an aqueous acid. What are the products generated in the first cycle.
PTH?Leu and Cys?Arg?Ser?Gln?Met
- Paralogous genes are _______.
the results of gene duplication.
- A fast and common method for determining the protein concentration in column effluent is _________.
measuring light absorption at 280 nm.
- In SDS-PAGE, disulfide-linked polypeptides can be separated after reacting the protein first with _________.
2-mercaptoethanol.
- Although a protein's primary sequence can be inferred from the nucleotide sequence, modifications such as ______ can be determined most easily by tandem mass spectrometry followed by protein database searching.
- phosphorylation
- disulfide crosslinks
- glycosylation
- acetylation
The pK1, pK2, and pKR of the amino acid histidine are 1.8, 9.3, and 6.0, respectively. The pK1, pK2, and pKR of the amino acid arginine are 1.8, 9.0, and 12.5, respectively. You have a mixture of histidine and arginine, how would you try to separate these two amino acids?
Cation exchange chromatography at pH 6.
- Either dansyl chloride or Edman's reagent can be used to identify the ________ of a protein.
N-terminal amino acid.
- Since there are 20 standard amino acids, the number of possible linear polypeptides of length N can be expressed as: ______
20^n
- You are trying to separate five proteins, which are listed below, by gel filtration chromatography. Which of the proteins will elute first from the column?
- cytochrome c (12 kDa)
- RNA polymerase (99 kDa)
- glutamine synthetase (621 kDa)
- interferon-γ (34 kDa)
- hemoglobin (62 kDa)
glutamine synthetase (621 kDa)
- Five graduate students prepare extracts from 5 different tissues. Each student measures the total amount of alcohol dehydrogenase and the total amount of protein in his or her extract. Which extract has the highest specific activity?
Total protein (mg) (Left)
Total alcohol dehydrogenase activity (units) (Right)
A 300 60,000
B 200 80,000
C 3000 96,000
D 5000 100,000
E 1000 200,000
B 200 80,000
- True or False: One of the keys to deciphering the function of a given protein is to understand its structure.
True
