Reduction/Oxidation Concept Help using NADH/NAD+

[Angela1]

Hello everyone~ I have a burning question. I was studying and came across this reduction/oxidation example under gluconeogenesis topic. The book stated that: NADH----> NAD+ is reduction and NAD+ ------> NADH is oxidation. I am very confused because I thought opposite. I thought that is the H is lost in NADH, that is oxidation, as oxidation is loss of electrons (or oxygen). Can someone please clear this concept up of oxidation/reduction. Thank you.

[Psycho]

Hello everyone~ I have a burning question. I was studying and came across this reduction/oxidation example under gluconeogenesis topic. The book stated that: NADH----> NAD+ is reduction and NAD+ ------> NADH is oxidation. I am very confused because I thought opposite. I thought that is the H is lost in NADH, that is oxidation, as oxidation is loss of electrons (or oxygen). Can someone please clear this concept up of oxidation/reduction. Thank you.

You are right to say that NADH --> NAD+ is oxidation and visa versa reduction, it could be a typing error (they happen) or it could be that the NAD part is a coupled reaction to the main gluconeogenesis reaction which is what they are actually referring to.

 

Oxidation is the loss of electrons or an increase in oxidation state

Reduction is the gain of electrons or a decrease in oxidation state

 

Many biological reactions are redox reaction where one molecule is oxidise while another is reduced.

[Angela1]

You are right to say that NADH --> NAD+ is oxidation and visa versa reduction, it could be a typing error (they happen) or it could be that the NAD part is a coupled reaction to the main gluconeogenesis reaction which is what they are actually referring to.

 

Oxidation is the loss of electrons or an increase in oxidation state

Reduction is the gain of electrons or a decrease in oxidation state

 

Many biological reactions are redox reaction where one molecule is oxidise while another is reduced.

 

Thank you soo much for helping to clear this up. I am thinking it may be a typo..

 

If you do not mind, would you care to expand a little more on what you meant by the possible coupling mechanism being why it is called 'reduced?'

[Psycho]

The process of gluconeogenesis start within the mitochondria, oxloacetate is reduced to malate using NADH which is turned to NAD+

 

In this case

 

Oxloacetate --> Malate = Reduction

NADH --> NAD+ = Oxidation

 

These could be said to be coupled reactions because they happen at the same time for the same purpose and as you can see though the main substrate is being reduced (Oxloacetate) a secondary substrate (NADH) is also being oxidised creating enzymatically coupled redox reaction.

 

The Malate is then transported out of the mitochondrion and the reverse happens

 

Malate --> Oxloacetate = Oxidation

NAD+ --> NADH = Reduction

 

This happens within the cytoplasm rather than in the mitochondrial matrix, this occurs due to there not being a transport protein across the mitochondrial membrane for malate.

 

This process also moves a reducing agent NADH out of the mitochondria and into the cell cytoplasm where it can be used to reduce other (non-mitochondrial based) reactions as well as supplying NAD+ to the mitochondria.

Edited October 8, 2011 by Psycho

[Angela1]

The process of gluconeogenesis start within the mitochondria, oxloacetate is reduced to malate using NADH which is turned to NAD+

 

In this case

 

Oxloacetate --> Malate = Reduction

NADH --> NAD+ = Oxidation

 

These could be said to be coupled reactions because they happen at the same time for the same purpose and as you can see though the main substrate is being reduced (Oxloacetate) a secondary substrate (NADH) is also being oxidised creating enzymatically coupled redox reaction.

 

The Malate is then transported out of the mitochondrion and the reverse happens

 

Malate --> Oxloacetate = Oxidation

NAD+ --> NADH = Reduction

 

This happens within the cytoplasm rather than in the mitochondrial matrix, this occurs due to there not being a transport protein across the mitochondrial membrane for malate.

 

This process also moves a reducing agent NADH out of the mitochondria and into the cell cytoplasm where it can be used to reduce other (non-mitochondrial based) reactions as well as supplying NAD+ to the mitochondria.

 

 

I see what you mean now. Wow, thank you so much for taking the time out to write this full explanation!! I appreciate it so much.