Second half BIOL 201

What is Kcat?

The amount of substrate molecules turned over to products by an enzyme when all the active sites are saturated

Is a high or low Kcat a powerful enzyme?

High Kcat is a more powerful enzyme

What is Km?

The concentration of the substrate when ½ Vmax is achieved

Is a high or low Km a powerful enzyme?

Low Km since you reach ½ Vmax with less substrate

What is the threshold energy for ATP synthesis?

+45 kJ/mol

How many protein components are in the ETC?

Protein: I, IIA, IIB, III, Cyt. C, IV

Lipid: Q

Which protein component in the ETC is a transmembrane protein and which is a peripheral protein

Transmembrane:

• I, IIA, IIB, III, IV

Peripheral:

• Cyt. C

What are the three main electron donors? Who do they donate to and how many protons?

NADH:

• Donates to Comp. 1

• Pumps 4 H+ to IMS

Succinate:

• Donates Comp. IIA

• Pumps 4 H+ to IMS

L-3-P:

• Donates to Comp. IIB

• Pumps 3 H+ to IMS

Do all the initial complexes (I, IIA, IIB) need to be functional to move e-?

No, any of the three is good enough since Q is downstream of these. But depending on which of the initial 3 is functional, will have different number of ATP produced

Everything after Q (III, Cyt. C, IV) has to be functional

What ETC component is the receiver of electrons?

Q is the receiver of e- from NADH, succinate, L-3-P

What is the flow of e-?

What is special about NADH in oxidation-reduction reaction?

It uses a hydride (2 e-, 1 H+)

The other molecules do their oxidation-reduction reaction using how many e- and H+?

2 e-

2 H+

What is the function of ETC?

Creates an H+ electro-concentration gradient across the IMM to store energy

Pumps protons from matrix to IMS

Where is the active site for ?

….

ATP synthase

• Active site is on the F1 complex

• Binds ADP + Pi

• Active site faces the matrix

What “things“ create a steady state?

ETC, ATP synthase, HPi transporter

work together to maintain specific concentration of reactants and products

How many H+ are needed to synthesize ATP?

4 H+ from the IMS to matrix via ATP synthase to make 1 mole of ATP

• 3 H+ from the ATP synthase

• 1 H+ from Pi transporter

What is the relationship between ETC and ATP synthase?

They are coupled together by…

• Concentration gradient across the membrane

  • ETC creates the concentration gradient

  • ATP synthase uses that concentration gradient to make ATP

What is a non-inverted mitochondrial vesicle and an inverted mitochondrial vesicle?

Non-inverted:

• Inside: Matrix

• Outside: IMA

• Components are facing the vesicle

• Acts like a normal mitochondria

Inverted:

• Inside: IMS

• Outside: Matrix

• The components are sticking out

How do electrons from cytosolic NADH enter the mitochondria?

Malate-Aspartate shuttle (predominant shuttle)

L3P shuttle in Complex IIB

What are the HEIs in SLP?

1,3 bisphosphoglycerate

Succinyl CoA

Phoshphonenol pyruvate

HEI have a delta G of what?

• 25 kJ/mol

Where does the PDH reaction occur?

Inner mitochondrial membrane

What enzyme is used for non-oxidative decarboxylation?

Decarboxylase

Pyruvate → Acetylaldehyde

What enzyme is used for oxidative decarboxylation?

Dehydrogenase

Pyruvate → dehydrogenase

How does pyruvate made from glycolysis get into the mitochondrial matrix?

It uses the pyruvate transporter