Talk:Urea cycle

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Wiki Education Foundation-supported course assignment

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

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

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 !

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

carbamoyl phosphate synthetase deficiency Link is wrongly redirected

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

Possibly wrong energy balance

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

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]