BIOCH200 Lecture Notes - Lecture 10: Tetrapeptide, Dipeptide, Asparagine

23 views4 pages

raspberryminnow639

4 Oct 2016

School

University of Alberta

Department

Biochemistry

Course

BIOCH200

Professor

Jonathan Parrish

For unlimited access to Class Notes, a Class+ subscription is required.

Document Summary

Polar side chains (uncharged: usually on protein surface, but may occur in the interior. Polar side chains: surface of protein. Peptide nomenclature: two amino acids + one petide bond = dipeptide, subsequent numbers follow this rule, peptides/oligopeptides. Long natural chain of amino acids: protein. Big polypeptide or many polypeptides with biological function. A dipeptide: directionality: n terminal ---> c terminal, however Is not the same as: directionality is different (different ordering) Tetrapeptide: only terminal amino and carboxylate groups retain charge, when amino acids combine together, they lose their formal charge (unless its on a side chain) Primary structure (1 : sequence of amino acid in a polypeptide. Covalent peptide bonds join each amino acid to the next. Every protein or polypeptide has a unique sequence. ** sequence --> structure --> function**: all peptides are amines but not all amides are peptides. Due to atoms surrounding the partial double bond.

Related Questions

1.) Protein kinases are involved in

A) the digestion of drugs to potentially toxic byproducts.

B) the degradation of enzymes to the component amino acids.

C) the phosphorylation of a wide variety of proteins.

D) the metabolism of drugs to water soluble compounds.

E) the cleavage of peptide bonds.

2.) Which of the following is triggered by the binding of glucose-6-phosphate to glycogen phosphorylase?

A) The protein changes from its T form to its R form.

B) The protein changes from its R form to its T form.

C) The protein becomes dephosphorylated.

D) It catalyzes the addition of a phosphate group to AMP.

E) It catalyzes the addition of a phosphate group to Ser-14.

3.) Which of the following amino acid residues are often involved in acid-base in enzyme-catalyzed reactions?

A) Histidine, aspartate, serine, and cysteine

B) Serine, tyrosine, arginine, and cysteine

C) Glutamine, asparagine, lysine, and tyrosine

D) Histidine, aspartate, lysine, and serine

E) Histidine, aspartate, glutamate, arginine, and lysine

blackchimpanzee753

Amino Acid	M.W. g/mol	pK_a for side chain
Alanine	89.1
Arginine	174.2	12.48
Asparagine	132.1
Aspartate	133.1	3.90
Cysteine	121.1	8.37
Glycine	75.0
Glutamate	147.1	4.07
Glutamine	146.1
Histidine	155.1	6.04
Isoleucine	131.2
Leucine	131.2
Lysine	146.2	10.54
Methionine	149.2
Proline	115.1
Phenylalanine	165.2
Serine	105.1
Threonine	119.1
Tryptophan	204.2
Tyrosine	181.2	10.46
Valine	117.1

Take a look at your pK_a table for the amino acids. It turns out that when these side chains are in a protein, they can have very different pK_a values. Explain the following observations:

a. In the enzyme medium chain acyl-CoA dehydrogenase (b-oxidation of fatty acids), E376 has a measured pK_a ~ 8.0. It is found in a very hydrophobic environment. What could account for it elevated pK_a?

b. For the enzyme aconitase (Krebbâs Cycle), a catalytic serine is known to have a pK_a ~ 8. What kind of factors could account for this decrease in pK_a?

lilacbee20

The peptide hormone vasopressin is used in the regulation of Na+ in many vertebrate. Porcine(pig) vasopressin has the sequence Asp-Tyr-Phe-Glu-Asn-Cys-Pro-Lys-Gly.

a) What is the pI of this peptide? Use the pKa values in the table on the last page for your calculations.

b) Could this peptide have an a helical secondary structure? Why or why not.

c) Will this peptide absorb UV light(280nm)? Why?

BIOCH200 Lecture Notes - Lecture 10: Tetrapeptide, Dipeptide, Asparagine

Document Summary

Get access

Related Documents

BIOCH200 Chapter Notes - Chapter 3 - 4: Heme, Hydrophile, Cooperative Binding

BIOCH200 Lecture Notes - Lecture 9: Disulfide, Thiol, Carboxamide

BIOCH200 Study Guide - Final Guide: Succinic Acid, Hexokinase, Cytochrome C

Related Questions