Biochemistry - Glycolysis - Discussion

Discussion :: Glycolysis - Section 1 (Q.No.5)

5. 

A kinase is an enzyme that

[A]. removes phosphate groups of substrates
[B]. uses ATP to add a phosphate group to the substrate
[C]. uses NADH to change the oxidation state of the substrate
[D]. removes water from a double bond

Answer: Option B

Explanation:

No answer description available for this question.

Deidre said: (Dec 5, 2014)  
From what I know kinase both add and remove phosphate groups, so A and B would be correct. Eg. Hexokinase adds the phosphate to Glucose to form Glucose 6 phosphate while pyruvate kinase removes the phosphate group from phosphoenolpyruvate to form pyruvate.

Hedaia said: (Dec 11, 2014)  
It is A and B, Kinase function transfer phosphate between ATP and Substrate.

Bijay Pradhan said: (Dec 8, 2015)  
You right @Hedaia kinase transfer phosphate between ATP and substrate.

Nabaggala Ashanant said: (Apr 21, 2016)  
It is B and A ie Pyruvate Kinase Enzyme removes a phosphate from pep. Addition of a phosphate group on the glucose by hexokinase enzyme.

Dr. Dutta said: (May 23, 2016)  
Pyruvate kinase enzyme transfers a P from phosphoenolpyruvate to ADP to form Pyruvic acid and ATP.

So kinase enzyme does not use ATP to add a phosphate group to the substrate.

Ebenezer Keteku Mensah said: (Jul 14, 2016)  
Yeah, I think the answer is A, but I referred to step one thus the addition of phosphate group by ATP.

Fifi said: (Aug 26, 2016)  
A and B both seem to be appropriate.

Hansel said: (Oct 27, 2016)  
I think it's A, because in step one hexokinase converts glucose to glucose-6-phosphate where one molecule of ATP is added to a phosphate to give ADP.

Alex said: (Nov 29, 2016)  
According to me, A and B are seems to be correct answers.

Kathiresan Krishnan said: (Mar 20, 2017)  
In fact kinases EXCHANGES (rather than adding) phosphate group from one high energy phosphate substrate to another low energy substrate.
It is true Kinases (hexokinase) "adds" (rather EXCHANGES) phosphate groups from one high-energy substrate (ATP) to low energy substrate (glucose).

In the case of pyruvate kinase, the same thing is true too. One substrate is ADP (low energy) and the other substrate is phospho-enol-pyruvate (high energy). Now the high energy molecule is phosphoenolpyruvate and the low energy molecule is ADP exchanges phosphate group. The phosphate exchange is carried out by a kinase.

Why do we say it adds instead of exchanges? That is what confuses everybody.

Let us see what phosphatase does?

I think phosphatase hydrolyses phosphate (Glucose-6-phosphate ) to Glucose and a FREE PHOSPHATE molecule. It DOES NOT exchange phosphate groups between substrates!

It is possible, those free phosphates combine with ADP to form ATP by the enzyme ATP synthase. I don't think phosphatase is capable of making ATP by itself. When we read glucogenesis, we assume that ATP is made by phosphatases from ADP. I suspect very much that is what really happening.

Disclaimer: This is just my speculation and open for debate! I need to read more to confirm that! You are welcome to criticise my explanation.

Thank you!

David Ndegwa said: (Jun 6, 2018)  
I agree A and B, whereby enzyme hexokinase from glucose consumes an ATP and adds to glucose 6 phosphate.

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