Enzymology Flashcards
What are the general reactions of amino acids?
Reactions due to the carboxyl side:
i) Decarboxylation
ii) Amine group formation
Due to the amino side:
i) Transamination
ii) Oxidative deamination
iii) Formation of carbamino compound
Due to the side chains
i) Transmethylation
ii) Ester formation by OH group
iii) Reaction of the amide group
iv) Reaction of SH group
Which of these proteins serve as a source of nitrogen for nucleic acid synthesis and why?
a) Arginine
b) Leucine
c) Glutamine
d) Proline
c) Glutamine
Amide group present in it serves as a source of Nitrogen for nucleic acid synthesis.
One of the most important functions of protein is?
Catalysis
Enzymes can increase the rate of reaction by a factor of ?
Up to 10^20
All catalysts are enzymes?
False.
Ribozyme is an RNA catalyst.
Non enzyme catalysts increase the rate of reaction by a factor of ?
10^2 or 10^4
The first enzyme to be recognized was?
urease
maltose
diastase
aminotransferase
diastase or amylase
Who discovered the first enzyme and what year?
French scientists Anselme Payen & Jean Persoz in 1833
First enzyme discovered in its pure state is? And what year?
Urease, crystallized from Jack beans in 1926 by James Sumner.
What are the residues in the active site of an enzyme called?
Catalytic group
What is the active site of enzymes?
This is the region that binds with the substrate and contributes residues that participate directly in the making and breaking of bonds
Residues that are close to eachother in the linear amino acid sequence interact more strongly than residues that are far apart
T/F
F
The 3D entity made up groups from different part of the amino acid sequence is the _____ of the enzyme?
Active site
All enzymes have active sites that are devoid of water
T/F
F.
Hydrolases use water as their reactant
How many amino acids are present in lysozyme?
129
What are the important groups in the active site of lysozyme?
Residue: 35, 52, 62, 63 & 101
What it is the importance of non polar characteristics of binding site crevices?
To enhance binding of substrates
Importance of residues in the active site of enzymes?
For recognition of substrates
Lock and key model off enzyme action was proposed by? When?
Fischer in 1894
Who proposed the lock and key model? When?
Fischer
1894
The active site has a shape that fits that if the substrate when binding is going on
T/F
F
Active site has the shape that complements that of the substrate only after substrate is bound.
What is the lock and key model postulation?
It proposes that the active site of the enzyme is the perfect fit for a specific substrate and that after the substrate is bound to the enzyme no other changes occurs.
Which of the active site theory predicts that the the residues in the active site enhance recognition of the substrate by the enzyme?
Induced fit hypothesis
Induced fit hypothesis
It assumes that the active site is flexible and continues to change shape until the substrate is completely bound.
Cofactor?
Nonprotein molecules required by some enzymes for enzymatic activities. They participate directly in substrate binding or in catalysis
Groups under cofactor
Coenzyme
Prosthetic group
Metal ion activator.
What is a coenzyme
A coenzyme is a non protein organic molecule that is loosely attached to the protein part
Functions of coenzymes?
- To serve as recyclable shuttles that carry many substrates from one point within the cell to another.
- They facilitate the recognition and binding of small chemical groups e.g folate, acetate, etc., to by their target enzymes.
- They stabilise species that are too reactive to stay for a significant period in water or organic molecules that permeate the cell interior.
Prosthetic group?
Nonprotein organic molecules tightly and stably incorporated into the protein’s structure by covalent or noncovalent bonds.