HELP!!! Kaplan or decks, who is right?

[elto]

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Aminoacid Degradation:
Kaplan says glutamate can be deaminated forming ammonia or can be used as an amino group donor in the synthesis of non essential a.a like aspartate.
Decks says: asparagine (wich is derived from aspartate) is not derived from glutamate!!! It says aspartate is derived from oxaloacetate..... 😕
I am lost....can please, someone explain??? Thanks... 🙁

 

[avantika]

it is based on transamination rxns which r reversible in nature. 2 types of rxn r there. ALT & AST. SO ur answer lies in AST rxn. i

glutamate can undergo transamination & oxidative deamination.

Aminoacid Degradation:
Kaplan says glutamate can be deaminated forming ammonia or can be used as an amino group donor in the synthesis of non essential a.a like aspartate.
Decks says: asparagine (wich is derived from aspartate) is not derived from glutamate!!! It says aspartate is derived from oxaloacetate..... 😕
I am lost....can please, someone explain??? Thanks... 🙁

 

[mam6701e]

it is based on transamination rxns which r reversible in nature. 2 types of rxn r there. ALT & AST. SO ur answer lies in AST rxn. i

glutamate can undergo transamination & oxidative deamination.

I agree with you about "glutamate can undergo transamination & oxidative deamination"

AST enz works on Aspartate (Transamination Rx):
aspartate + alpha-ketoglutarate <---> oxalacetate = glutamate

ALT enz doesnt work on aspartate, it works on alanine (Transamination Rx):
alanine + alpha-ketoglutarate <---> pyruvate + glutamate

the enz that works on the desamination of glutamate is glutaminase

So, glutamate goes:
transamination trough AST and
Desamination trough Glutaminase

 

[mam6701e]

error error error error

 

[mam6701e]

Aminoacid Degradation:
Kaplan says glutamate can be deaminated forming ammonia or can be used as an amino group donor in the synthesis of non essential a.a like aspartate.
Decks says: asparagine (wich is derived from aspartate) is not derived from glutamate!!! It says aspartate is derived from oxaloacetate..... 😕
I am lost....can please, someone explain??? Thanks... 🙁

First sentence is true:
"glutamate can be deaminated forming ammonia (desamination) or can be used as an amino group donor in the synthesis of non essential a.a like aspartate (transamination)."

Second sentence is true:
"aspartate is derived from oxaloacetate."

aspartate + alpha-ketoglutarate <---> oxalacetate + glutamate

aspartate (a.a) yields its amino group to alpha-ketoglutarate (alpha keto acid) ------>
-aspartate becomes oxalacetate (alpha keto acid)
-alpha-ketoglutarate becomes glutamate (amino acid) or viceverse

glutamate (a.a) yields its amino group to oxalacetate (alpha keto acid) ----->
-glutamate (a.a) becomes alpha-ketoglutarate (alpha keto acid)
-oxalacetate (alpha keto acid) becomes aspartate (a.a)

"oh my gosh I am dizzy" 😳

So they yield their amino NH3 group back and forward for only one reazon...................NH3 is to toxic to be hanging around the body by its self, so it needs to be carried by something and no to be alone

 

[avantika]

deamination rxn is carried out by glutamate dehydroginase.


Desamination trough Glutamine synthetase[/COLOR][/QUOTE]

 

[elto]

Thank you guys for your input...it seems that I need to put more hours of study... 🙁

 

[mam6701e]

deamination rxn is carried out by glutamate dehydroginase.


Desamination trough Glutamine synthetase[/COLOR]

[/QUOTE]


you are right it is not Glutamine synthetase, But a i am not sure if it could be glutamate dehydroginase. Cos glutamate dehydroginase is An enzyme that catalyses the conversion of l-glutamate and water to 2-oxoglutarate and nh3 in the presence of NAD+. So it releases NH3
The idea here is to release an NH3, so we can use it to form urea.

On that case there is another enz that make desamination
the other enz that transform glutamine to glutamate and releases an NH3 is glutaminase and transform glutamine to glutamate
Glutamine synthetase does the oposite
Sorry guys if I made yuo get confused, but now Iam 100 % sure.

 

[docapd]

glutamate dehydrogenase is used in oxidative deamination of Glutamate.
Glutamate + nad+ --------------> alpha ketoglutarate+ NH4+

NH4+ GOES INTO UREA CYCLE.

 

[mam6701e]

glutamate dehydrogenase is used in oxidative deamination of Glutamate.
Glutamate + nad+ --------------> alpha ketoglutarate+ NH4+

NH4+ GOES INTO UREA CYCLE.

so, we have two enz that desaminate glutamate:
glutaminase
and
glutamate dehydrogenase 😀

 

[docapd]

so, we have two enz that desaminate glutamate:
glutaminase
and
glutamate dehydrogenase 😀

Hey........ wasn't around ,so cudn't reply earlier.No...you got it wrong.
As much as i understand........

Glutaminase is used in deamination of Glutamine which is syn. by skeletal m. & brain and taken up by kidney & liver.
2 sequential rexns. occur & NH3 is released in both.(it goes into urea cycle) as i said before.

Glutamine----------->Glutamate+ NH3

AND then, GDH-glutamate dehydrogenase is used in oxidative deamination of Glutamate produced in 1st rexn.

Glutamate + nad+ --------------> alpha ketoglutarate+ NH4+

Hope it is clear now................