Enzyme kinetics 2

Question 1

What percentage of reactions are bisubstrate?

Answer 1

60%

Question 2

Bisubstrate reactions are normally what type of reaction?

Answer 2

Transferase

Redox reaction

Question 3

What are the two types of sequential reactions?

Answer 3

random - substrates enter in any order

ordered - substrates enter in a set order, B almost acts as an inhibitor to the reaction

Question 4

What is a ping pong reaction?

Answer 4

One or more product released before all substrates have combined with the enzyme

Question 5

What is the standard nomenclature for substrates?

Answer 5

A,B,C,D …. in the order they enter the enzyme

Question 6

What is the standard nomenclature for products?

Answer 6

P,Q,R,S,T in the order they leave the enzyme

Question 7

What is the general way in which lipases break down lipids?

Answer 7

Hydrolysing the ester of fatty acids

Question 8

Where is triacylglycerol primarily secreted?

Answer 8

From the pancreas but also found in the salvia and stomach

Question 9

What does phospholipase A2 cleave?

Answer 9

The second fatty acid from carbon 2 of a phospholipase

Question 10

What metal is required in phospholipase A2 catalysis?

Answer 10

Ca2+

Question 11

How does the triacylglycerol lipase work?

Answer 11

Learn the fucking mechanism bitch (dogs have seen lephricorns fucking)

Question 12

What is the rate limiting step of phospholipase A2 catalysis?

Answer 12

The degradation of the tetrahedral intermediate

Question 13

What is a monotopic protein?

Answer 13

Bound to one side of the membrane

Question 14

What is a multispan protein?

Answer 14

A protein that spans both layers

Question 15

Bacteria with one membrane are called

a) gram negative
b) gram positive

Answer 15

b) gram positive

gram negative 2 membranes

Question 16

What is lipid A?

Answer 16

A lipid component of a lipopolysaccharide (LPS) which is responsible for toxicity of gram negative bacteria (part of outer membrane)

Question 17

What catalyses the formation of Lipid A?

Answer 17

LpxC - it is a zinc dependant deacty/lase with two zonc ions bound in the active site. It catalyses

Question 18

What does LpxC catalyse the deacetylation of?

Answer 18

UDP-3-O-GlcNac. This is the committed step of lipid A biosynthesis

Question 19

Is histidine actively involved in the acetylation of UDP-3-O-GlcNac by LpxC?

Answer 19

Yes, this was the key difference in the alternative mechanism which is now believed to be true.

Question 20

Glycotransferase (GT) and transpeptidase (TP) enzymes are involved in what?

Answer 20

The synthesis of the bacteria cell wall.
GT - catalyses the formation of the glycosidic linkage to form glycoside
TP - cross links the peptidoglycan chains to form rigid walls

Question 21

What inhibits the activity of TP?

Answer 21

beta-lactams (e.g. penicillin), glycopeptides (e.g. vancomycin), and glycolipopeptides
(antibiotics)

Question 22

GT transfers a WHAT from the corresponding sugar nucleotide donor substrate to a specific hydroxyl group sugar or to other acceptors (e.g. lipids)?

Answer 22

glycosyl residue

Question 23

Peptidoglycan transglycosylation by the enzyme GT takes place through polymerisation of lipid II substrates. What is lipid II?

Answer 23

An amphipathic peptidoglycan precursor molecule involved in the synthesis of the cell wall of bacteria.

Question 24

What does TP form cross links between?

Answer 24

Between the D-ala residues

Question 25

What Is the lysozyme structurally similar to?

Answer 25

Glycosyltransferase (GT), however lysozyme CLEAVES glycosidic bonds