Talk:Urea cycle

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Wiki Education Foundation-supported course assignment[edit]

This article is or was the subject of a Wiki Education Foundation-supported course assignment. Further details are available on the course page. Student editor(s): Anhill95. Peer reviewers: Majumak, Ashbyaa.

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Wiki Education Foundation-supported course assignment[edit]

This article was the subject of a Wiki Education Foundation-supported course assignment, between 27 August 2019 and 6 December 2019. Further details are available on the course page. Student editor(s): Mdterry24, Eal13lanc, Lexilyman, Pmaymicro. Peer reviewers: R7Seven, SpiralOut KeepGoing, Matthewmendoza, Nefimor7, Ztwitchell76.

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Synthesis[edit]

CO₂ + 2 NH₄⁺ + 3 ATP + aspartate + 2 H₂O --> urea + 2 ADP + 2 P_i + AMP + pyrophosphate (PP_i) + fumarate

I think the stoichiometry of urea synthesis should be the above. Peter Klaren 15:26, 5 October 2006

Location of urea cycle[edit]

Should be added that it primarly happenes in the liver but other tissues are capable of doiing it, like the brain(to small extend)—Preceding unsigned comment added by M siterman (talk • contribs)

what will be happened if ammonia concentration is increased in brain?? —Preceding unsigned comment added by 210.1.247.92 (talk) 18:25, 11 February 2011 (UTC)[reply]

I would very much like that remark, when I'm studying, I try to see where do each of the reactions take place a lot of times. Although I don't know about that happening in the brain.--Orangutan45 (talk) 04:03, 25 May 2016 (UTC)[reply]

Arginase presented differently elsewhere ![edit]

The following issues about arginase have been mentioned variably elsewhere:

1- Arginase deficiency can cause hyperammonemia.

2- the exception in the case of arginase in contrast to other enzymes was mentioned in an opposit way: Arginase deficiency "unlike other enzymes of the urea cycle" do not prevent ureagenesis. and (although increased substrate concentration is a reason) but still they believe it is due to the presence of another isoenzyme "Arginase II" in the kidney that can compensate when arginine concentration raise.

Yasir muhammed ali (talk) 11:29, 11 April 2016 (UTC)[reply]

wrong redirection[edit]

carbamoyl phosphate synthetase deficiency Link is wrongly redirected

Yasir muhammed ali (talk) 10:29, 14 April 2016 (UTC)[reply]

Possibly wrong energy balance[edit]

About this piece:

"The two NADH produced can provide energy for the formation of 4 ATP (cytosolic NADH provides only 1.5 ATP due to the glycerol-3-phosphate shuttle who transfers the electrons from cytosolic NADH to FADH2 and that gives 1.5 ATP), a net production of one high-energy phosphate bond for the urea cycle."

1-First maybe we could clarify that one NADH generates, not just 1.5 ATP, but 1.5 high-energy bonds. Because saying it generates 1.5 ATP per NADH, could mean 2.5 or 1.5 high-energy bonds per NADH.

2.5:(1 full ATP, and 1 ADP, or half ATP)

1.B - But, besides that, if NADPH is generating 1.5 ATP, how are two NADPH generating 4 ATP? It would be 3, I think. In the end, it is generating 3 high energy bonds.

2-Furthermore, the urea cycle spends 4 high-energy bonds (2 ADP, 1 AMP), so even when producing 4 of them (as the text says), why would the cicle be having a "net production of one high-energy P bond"? At last, the cicle is spendind 4 high energy bonds, and generating 3.

3-And last, also maybe, if we are going to mess with shuttles, you could add that in the malate-aspartate shuttle cells (whichever those cells are (idk...)), the generation is... 2.5 high energy bonds per NADH, generating 2 high energy bonds more per urea

So: The cycle is generating 3 high energy bonds, and spending 4, 1 more than it generates (and maybe you could clarify the "generating 1 ATP per NADH", or not). And, maybe also, if we are going to add the shuttles, we could clarify for both of them.

Anyone thinks the same?

--Orangutan45 (talk) 01:28, 25 May 2016 (UTC)[reply]

Enzymes involved + table[edit]

Would it be possible to add a table listing the enzymes? We have all compounds listed in a table in the main wikipedia article, but not all enzymes yet. My list includes carbamoyl phosphoate synthetase, ornithine transcarbamoylase, argininosuccinate synthetase, argininosuccinase and arginase but I am not 100% sure if these are correct. Either way, a table overview may be helpful. This is often asked in biochemistry-exams e. g. about the urea cycle, localization, substrates + enzymes involved. Edit: I just noticed that the enzymes are there, but as abbreviation. I think it may be better to also list both the long variant names, and then in () the abbreviation. It is harder to remember abbreviations, in my opinion. 2A02:8388:1641:8380:8920:7EEB:D50A:6466 (talk) 16:28, 30 October 2019 (UTC)[reply]