Lecture 11

Question 1

Edman Degradation

Answer 1

Amino Acid’s are cleaved from the N-terminus and identified one by one using PTH derivative analysis
-Most widely used modern method for protein sequencing

Question 2

What does it mean to denature a protein?

Answer 2

Destroy the three dimensional structure of a protein so that it exists only has a single simple chain of amino acids

Question 3

How can a protein be denatured?

Answer 3

In any way that disrupts the non-covalent bonding forces responsible for 2º, 3º, and 4º structure

• Chemical reagents including strong hydrogen bonding molecules like urea and gaunidinium ion
• Changing the Ph. Altering ionic charges of acidic/basic AA side chains
• Heat/Physical Agitation/Organic solvents

Question 4

Oxytocin

Answer 4

Octapeptide hormone that has a disulfide bridge; Active in many aspects of sexuality and reproduction

Question 5

Vasopressin

Answer 5

Differs from oxytocin only in substitution of Arg for Leu and Phe for Ile; Regulate blood flow

Question 6

Cyanogen Bromide

Answer 6

Common method for cutting up proteins

-cuts the protein on the carboxyl side of the methionine residue

Question 7

Peptidase Enzymes

Answer 7

Catalyze amide hydrolysis with near complete specificity for only a few amino acid types

Question 8

Trypsin

Answer 8

Digestive enzyme that hydrolyzes proteins selectively on the carboxyl side of lysine and arginine residues
-Both side chains are basic

Question 9

Chymotrypsin

Answer 9

Pancreatic digestive enzyme, cuts a protein chain on the carboxyl side of phenylalanine, tyrosine and tryptophan

• Common feature is presence of an aromatic ring in side chain
• Enzyme has a large hydrophobic pocket that accepts the non-polar side chain

Question 10

Sequence Motifs

Answer 10

Refers to a particular pattern of amino acids

-proteins that share sequence motifs are likely to be related in some way