peptides 9/14

Question 1

what are alpha amino acids joined by and what is the reaction between

Answer 1

joined by an amide linkage and a condensation rxn bt an amino and carboxylic acid; the bond can be broken by a hydrolysis rxn

Question 2

what are the amide linkages of a peptide called

Answer 2

peptide bonds

Question 3

what is the difference between naming for amino acids with a few residues vs many

Answer 3

few: oligopeptide
many: polypeptide

Question 4

what do all peptides have

Answer 4

amino terminal and carboxyl terminal

Question 5

what do names or primary structures start with

Answer 5

N-terminal (amine group)

Question 6

how are peptide structures described

Answer 6

baackbone and side chains

Question 7

since amino acids may be post translationally modified…

Answer 7

peptides and proteins may consist of more than 20 diff amino acids

Question 8

since peptides have characteristic ionization behavior and pI

Answer 8

ion exchange chromatography and isoelectric focusing can be used to isolate them

Question 9

where are disulfide bonds found

Answer 9

extracellularly

Question 10

how can molecular weight be estimated

Answer 10

110/residue

Question 11

oligomeric proteins have

Answer 11

two or more identical subunits called protomers such as hemoglobin that has 2 alpha/beta protomers

Question 12

what is composition and how is it determined

Answer 12

proportion that each amino acid contributes to the total; determined by complete acid hydrolysis followed by HPLC (high performance liquid chromatography)

Question 13

what are prosthetic groups

Answer 13

contribute to protein function

Question 14

what are conjugated proteins

Answer 14

proteins with prosthetic groups

Question 15

what are halo enzymes/proteins and apoenzymes/proteins

Answer 15

halo=protein with prosthetic group attached

apo=protein without prosthetic group attached

Question 16

what is primary structure

Answer 16

amino acid sequence (covalent structure includes crosslinks like disulfide bonds)

Question 17

secondary structure

Answer 17

3D conformations that are stable because of characteristics and backbone

Question 18

tertiary structure

Answer 18

3D folding of the peptide

Question 19

quaternary structure

Answer 19

association of subunits in multisubunit proteins

Question 20

denaturation

Answer 20

loss of native, functional secondary, tertiary, and quarternary structure

Question 21

what is the ultimate goal of protein structure studies

Answer 21

1. understand functional contribution of each amino acid
2. understand functional difference between alleles and variants
3. be able to manipulate protein function by drugs and/or gene therapy