Biochemistry - Glycolysis - Discussion

Discussion Forum : Glycolysis - Section 1 (Q.No. 5)
5.
A kinase is an enzyme that
removes phosphate groups of substrates
uses ATP to add a phosphate group to the substrate
uses NADH to change the oxidation state of the substrate
removes water from a double bond
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
11 comments Page 1 of 2.

DAVID NDEGWA said:   6 years ago
I agree A and B, whereby enzyme hexokinase from glucose consumes an ATP and adds to glucose 6 phosphate.
(1)

Kathiresan Krishnan said:   7 years ago
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!
(1)

Alex said:   7 years ago
According to me, A and B are seems to be correct answers.

Hansel said:   7 years ago
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.

FIFI said:   8 years ago
A and B both seem to be appropriate.

Ebenezer Keteku Mensah said:   8 years ago
Yeah, I think the answer is A, but I referred to step one thus the addition of phosphate group by ATP.

Dr. Dutta said:   8 years ago
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.

NABAGGALA ASHANANT said:   8 years ago
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.

BIJAY PRADHAN said:   8 years ago
You right @Hedaia kinase transfer phosphate between ATP and substrate.

Hedaia said:   9 years ago
It is A and B, Kinase function transfer phosphate between ATP and Substrate.


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