Lesson 3: Peptides & Classification of Proteins Flashcards
What are peptides ?
Short sequences of amino acids linked together by covalent bonding
How are peptides formed ?
Carboxyl Group of an amino acid with an Amino Group of another amino acid
How is an aa read ?
From N-terminus
What is hydrolyctic cleavage ?
Cleaving peptide bonds to their constituant amino acids by the hydrolysis of peptide linkages
What is the Acid-Base behavior of a peptide dependent on ?
N-terminus , C-terminus , Ionizable R-group
What is labelling by FDNB ?
Amino terminal named as 1-fluro-2,4-dinitrobenzene
useful for the determination of primary structure of the peptide
What is labelling by FDNB ?
Amino terminal named as 1-fluro-2,4-dinitrobenzene
useful for the determination of primary structure of the peptide
How many aa residues does glutathione have ?
3
glutamate, cysteine and glycine
What are the functions of Glutathione ?
1)co-enzyme
2)participates in the second phase of the xenobiotic metabolism
3) reduce hydrogen peroxide (free radicle damaging to tissues) to water (antioxidant action)
How do trypsin and chymotrypsin bring about hydrolysis of peptide bonds ?
Through Proteolytic Cleavage
action is highly specific
What is Thyrotropin-releasing hormone (TRH) ?
a tripeptide released from the hypothalamus
How many aa residues does TRH have ?
3
Pyroglutamate-Histidine-Proline
What are enkephalins also known as ?
endogenous opiates
bind to receptors same to which synthetic opiates ex:morphine bind to
What does oxytocin do ? How many aa residues ?
Stimulates uterine contractions. 9
What does Glucagon do ? How many aa residues ?
Pancreatic hormone –> glucose homeostasis. 29
What is Partial Double Bond Character ?
- single bond (C–N) does not show rotational freedom
- the peptide bond is actually resonance hybrid of two electron isome
aExplain φ and ψ Angles.
- Rotation around the nitrogen-and- α carbon bond is measured as the f φ(phi) angle
- Rotation around the peptide carbon and α -carbon bond as the c ψ(psi) angle
allow proteins to fold into secondary structures
T/F: The peptide bond is positivaley charged.
False. Uncharged
T/F: O and H are in CIS position
F. Trans
What are the substituents of the peptide bond atoms ?
1) Alpha Carbon 1
2) Alpha Carbon 2
3) H atom
4) O atom
What results in the H-Bond between the O and H in a peptide ?
The sharing of electrons between the C and the N.
