Degradation of Amino Acids Flashcards
Protein Digestion, Amino Acids, Tissue Utilization, Degradation of Amino Acids, Fate of Carbon Core, Urea Cycle
1
Q
BUN in pregnancy
A
decreased
2
Q
other sources of alanine besides the muscle
A
kidney and intestines
3
Q
CPSI deficiency
A
Type I hyperammonemia
4
Q
the second step of urea cycle
A
citrulline synthesis
5
Q
Aspartate + citrulline +ATP —> argininosuccinateWhat happes to the nitrogen of aspartate?
A
gets incorporated into urea
6
Q
an alternative to low protein diet aimed at reducing the ammonia load on the urea cycle
A
scavenger drugs
7
Q
BUN in liver damage
A
decreased
8
Q
high levels of N-acetyl glutamate leads to
A
increased CPSI activity
9
Q
blood citrulline level in type I and type II
A
low for both
10
Q
Glutamate directly provides nitrogen (NH4+) to urea cycle through
A
deamination by glutamate dehydrogenase
11
Q
The only place that urea cycle takes place in
A
liver
12
Q
The two precursors of argininosuccinate
A
citrulline and aspartate
13
Q
the reaction catalyzed by carbamoyl phosphate synthetase I
A
CO2 + NH4+ – 2ATP —> carbamoyl phosphate
14
Q
Glutaminase
A
the enzyme in the kidney that forms NH4+ and glutamate from glutamine
15
Q
ALT
A
alanine aminotransferase(Alanine/ a-ketoglutrate) and (pyruvate/ glutamate)
16
Q
the amino acids that can undergo deamination
A
glutamate, glycine, serine, threonine, histidine
17
Q
the product of the step of urea cycle is transported into the cytosol
A
second step. citrulline gets transported to cytosol
18
Q
two methods for carbamoyl phosphate synthesis
A
1- Mitochondria- urea cycle and CPSI2- from glutamine and CO2 by CPSII in cytosol (–> pyrimidine synthesis)
19
Q
when to provide arginine as urea cycle intermediate
A
if argininosuccinate lyase is defecient.
20
Q
ALT level 36hours after ingestion of toxic mushroom
A
ALT reaches 20X its normal level after 36 hours.Indicates liver cell necrosis- liver as the site for toxic removal
21
Q
the deficiency of argininosuccinate lyase cased
A
argininosuccinyl acidemia
22
Q
the first step in urea synthesis
A
CO2 + NH4+ – 2ATP —> carbamoyl phosphate
23
Q
function of glutamate dehydrogenase in other tissues , EXCEPT the liver and kidney
A
formation of glutamate and water from a-ketoglutarate and NADP+
24
Q
argininemia is caused by
A
the deficiency of arginase which catalyzes the cleavage of arginine
25
main detoxification reaction in brain is catalyzed by this enzymeHint: 1/3 enzymes that fixes free ammonia
glutamine synthetase
26
the coenzyme of transaminase
PLP- pyridoxal phosphate
27
deamidation
removal of amide group from glutamine and asparagine as NH4+
28
BUN and blood ammonia in liver damage
BUN decreased in liver damage But blood ammonia increased during liver damage
29
importance and the enzyme deamidation of glutamine in kidney
important in kidneyprovides most of the NH4+ in the urineNH3 aids the secretion of protons into the urine and indirectly helps to balance blood PH.Glutaminase is the enzyme
30
the fate of fumarate as a by product of arginine synthesis (argininosuccinate lyase)
enters the TCA cycle and regenerate oxaloacetate and then aspartate.
31
carbamoyl phosphate synthesis of urea cycle takes place in
mitochondria
32
blood nitrogen metabolites
blood urea nitrogen (BUN)creatinine uric acidammonia
33
The impact of high levels of arginine production on urea production
increased urea production though1- high n-acetyl glutamate --> increased CPSI --> increased urea production2- increased ornithine production --> increased urea production
34
BUN in kidney damage
increased
35
how to reduce ammonia load on the urea cycle
low protein diet, avoid fasting - to limit amino acid degradation
36
Nitrogen is carried to the liver by
alanine and glutamine
37
activates CPSI
N-acetyl glutamate
38
The two amino acids that undergo deamidation
glutamine and asparagine
39
name at least three condition in which plasma ALT And AST are elevated
cirrhosishepatitisliver toxicity
40
Glutamine ---?---> glutamate ---?--> a-KGLIVER
GlutaminaseGDH
41
cleavage of arginine into urea and ornithine is catalyzed by
arginase
42
the only way arginie is produced in human body
arginine synthesis via argininosuccinate lyase in cytosolArgininosucccinate ---> fumarate + arginine
43
arginase cleaves argininie into
urea and ornithine
44
conversion of glutamine to alanine
glutamine first to glutamate- E: glutaminaseGlutamate to alanine- E- ALLT
45
the central role of glutamate in nitrogen removal
transamination - collect nitrogendeamination- provides nitrogen to the urea cycle by glutamate dehydrogenasetransaminating oxaloacetate into asparte- provides nitrogen indirectly to the urea cycle. Aspartate then provides an amino group to ureaprecursor for the allosteric activator of the urea cycle
46
high levels of arginine leads to
high levels of N-acetyl-glutamateIncreased ornithine production
47
the energy requirement of argininosuccinate synthesis
1 ATP
48
the energetics of the urea cycle
aspartate + NH3 + CO2 +3ATP --> Urea + fumarate + 2ATP + 2P + PP + 3H2o
49
Increased CPSI activity leads to
Increased urea production
50
energy requirement of carbamoyl phosphate synthesis for urea cycle
2ATP
51
Increased ornithine production leads to
increased urea production
52
The allosteric regulator of CPSI
N-acetyl-glutamate
53
how to limit amino acid degradation
low protein diet and avoid fasting
54
CPSI or N-acetylglutamate synthase deficiency causes
Type I hyperammonemia
55
the only X-linked recessive primary hyperammonemias
type II hyperamoonemia- ornithine transcarbamoylase
56
argininosuccinate synthesis takes place in
cytosol
57
after citrulline synthesis, it is transported to the
cytosol
58
Urine orotate for type I a nd type II
type I - lowType II- HighThe only differentiating factors. Other values are identical for the two.
59
ornithine transcarbamoylase catalyzes the synthesis of -------- in ------.
citrulline in mitochondria
60
amino acid degradation takes place in all tissues. How does nitrogen gets to the liver?
Nitrogen is carried to the liver by ALANINCE and GLUTAMINE
61
defeciency in ornithine transcarbamoylase
type II hyperammonemia
62
aminotransferase
transaminase- an enzyme for the reversible reaction of transamination.
63
activates the synthesis of N-Acetylglutamate
HIGH levels of arginine
64
as the utilization of amino acids decreases, urea production ------
decreases
65
deamination
removal of a-amino group from certain amino acids as NH4+glutamate, glycine, serine, threonine, histidine
66
net glutamine producers
muscle and brain
67
PLP
pyridoxal phosphate
68
The role of glutamate in the following reactionGlutamate + Acetyl-CoA --> N-acetyl Glutamate
1- allosteric activator2- provides nitrogen
69
blood ammonia in urea cycle disorders
increased
70
how many high energy phosphate bonds are broken and what does it mean for the urea cycle
4 high energy bonds are broken, which makes the cycle irreversible
71
how can part of the used energy in urea cycle be recovered?
if fumarate enters the TCA cycleFumarate --> Malate _> Oxaloacertate--> Aspartate and 1 NADH ~ 2.5 ATP through oxidative phosphorylation
72
CPSI
carbomyl phosphate synthetase I catalyzes the carbamoyl phosphate synthesis- The rate limiting and committed step of urea cycle
73
three enzymes that can fix free ammonia into organic molecules
glutamate dehydrogenaseglutamine synthetasecarbamoyl phosphate synthetaseI
74
The reason for decreased level of nitrogen metabolites during pregnancy
increased GFR
75
Glutamine --?--> glutamate ---?--> alanine
glutaminase, ALT
76
The main pathway of amino acid nitrogen removal is
transamination
77
Citrulliunuria type I
deficiency of argininosuccinate synthase
78
the benefit of limiting amino acid degradation
reducing the ammonia load in the urea cycle
79
the autosomal recessive primary hyperammonemias
type I, citrullinuria type I, argininosuccinic acidemiaargininemia
80
arginine synthesis is catalyzed by
argininosuccinate lyase
81
the rate limiting and committing step of the urea cycle is
carbamoyl phosphate synthesis
82
transamination
transfer of an a-amino group from an amino acid to an a-keto acid
83
is a precursor for the allosteric activator of the urea cycle
glutamate
84
the role of citrulline suppliment in type I and II hyperammonemia
to capture aspartate so at least one nitrogen can be excreted
85
deficiency causes citrullinuria type I
argininosuccinate synthetase
86
1---- + 2---- --(GDH)---> NADP+ + Glutamatemuscle and peripheral tissues
a-KG + NH4+required for glutamine transport
87
during transamination, the amino acid nitrogen is generally collected on
glutamate
88
main glutamine users
kidney, gut, immune cells and liver
89
Three ways to supply the amino acid pool
1- degradation of bodies own protein (endogenous)2- degradation of dietary protein (exogenous)3- synth. of non-essential aa from other pathways
90
glutamate indirectly provides nitrogen to urea by
transaminating oxaloacetate into aspartate. Aspartate then provides an amino group to urea.
91
high levels of ALT and AST in plasma indicates
liver damage
92
the reaction catalyzed by glutamate dehydrogenase
a-ketoglu + NH4+ glutamate
93
blood arginine level for type I and type II
both low
94
blood NH3 level for type I and type II
both high
95
starvation and the brain
during starvation the brain switches from glucose to ketone bodies (MAINLY FROM FATTY ACIDS) as energy source.
96
glutamate dehydrogenaseresults in the formation of these compound in the kidney and liver
NADPH, a-ketoflutarate, NH4+ and H+Substrate: Glutamate and HOH
97
Urea is transported to the ------ and excreted in --------. some urea leaves through the -----, too.
urea transported to the kidney and excreted in urine.some urea leaves through intestine
98
the transamination reaction is ------ and ------- catalyzes the reaction.
reversible, transaminase (aminotransferase)
99
citrulline and aspartate form argininosuccinate. what is the source of aspartate?
aspartate is produced by transamination of oxaloacetate (AST) and the aspartate nitrogen will incorporate into urea
100
fasting and muscle proteins
during fasting muscle proteins are degraded and amino acids are transported to the liver and converted to glucose.And the Nitrogen of the used amino are converted to urea.
101
scavenger drug for glycine
benzoate + glycine --> hippuric acid --> excretion
102
pyridoxine
B6
103
treatment of urea cycle disorders
a- reduce the ammonia load on the urea cycleb- provide urea cycle intermediates
104
cleavage of arginine into urea and ornithine takes place in
the cytosol
105
the first step in urea synthesis is catalyzed by
carbamoyl phosphate synthetase I
106
blood ammonia in liver damage
increased
107
#NAME?
N-acetylglutamate
108
amino acid degradation takes place in
all tissues
109
deficiency of arginase causes
argininemia
110
argininosuccinate synthesis is catalyzed by
argininosuccinate synthetase
111
arginine as a reactant for nitric oxide synthesis
Arginine +NADPH + O2 --> citrulline +NO + NADP+ + H2O
112
it can provide nitrogen both directly and indirectly to the urea cycle
glutamate
113
citrulline synthesis is catalyzed by
ornithine transcarbamoylase
114
the precursors of N-acetyl glutamate
glutamate and Acetyl CoA
115
The role of Arginine in the following reaction:Glutamate + Acetyl-CoA --> N-acetyl Glutamate
Arginine is + (activator)
116
ALT specificity vs AST
ALT is more specific
117
CPSII
the enzyme for carbanmoyl phosphate synthesis in the cytosol from glutamine and CO2
118
BUN and blood creatinine in kidney damage
increased
119
the first two intermediates of the urea cycles which are made in the mitochondria
carbamoyl phosphate and citrulline
120
urea cycle starts in ----- and is completed in the -----.
starts in mitochondria and completed in cytosol.
121
the major reaction in the muscles that constitute the main source of alanine
protein degradation and transamination
122
AST
aspartate aminotransferase(Oxaloacetate/glutamate) and (Aspartate/a-ketoglutrate)
123
scavenger drug for glutamine
Phenylbutyrate
124
BUN, blood creatinine and blood uric acid level during pregnancy
decreased
125
its deficiency causes argininosuccynyl acidemia
argininosuccinate lyase
126
sources of alanine- alanine transport to the liver: Glucose/Alanine Cycle
main: muscle (result of protein degradation and transamination)Other: kidney and intestine (conversion of glutamine to alanine)
127
Blood creatinine in kidney damage
increased
128
scavenger drugs
conjugate amino acids and target them for urinary excretion
129
this vitamin is required for PLP formation
Vitamin B6- pyridoxine
130
The third step of urea cycle
argininoscuccinate synthesis
131
transports ornithine into the mitochondria from the cytosol
ornithine translocase
132
ornithine translocase
transports ornithine into the mitochondria from the cytosol
133
blood uric acid in pregnancy
decreased
134
conditions that resemble fasting as well as high protein diet and excessive degradation -------- urea synthesis and ------ synthesis of urea cycle enzymes.
increase, increase
135
arginine ---> urea and ornithineE: arginasethe fate of the arginine and ornithine
arginine cab be used by other pathways: protein synthesis and nitric oxide synthesisornithine moves back to mitochondria and reacts with another molecule of carbamoyl phosphate
136
the reactions that lead to the formation of alanine in kidney and intestine
conversion of glutamine to alanine
137
the reaction catalyzed by glutamine synthetase
Glutamate + NH4+ ----- ATP ---> glutamine
138
the product of transamination of oxaloacetate (AST)
aspartate
139
arginine synthesis takes place in
cytosol
140
blood uric acid in gout
increased
141
diagnostic tool for primary hyperammonemias
metabolites before the deficiency accumulates in blood/ urine.Metabolites after the deficiency have much lower levels.
142
The central role of glutamate in nitrogen removal- 3 general descriptions
precursor for allosteric activatorProvides nitrogen in two different wayscollects nitrogen
143
when to provide citrulline supplement as urea cycle intermediate
In type I and II hyperammonemia.it captures aspartate, so at least one nitrogen can be excreted
144
Three general ways to deplete amino acid pool
1- protein synthesis for the body2- consumption of aa as precursor for small nitrogen containing molecules3- conversion of amino acids to glucose, glycogen, a-Kbodies, and fatty acid oroxidation to Co2 and H2o
145
regulation of the urea cycle
N-acetylglutamate (allosteric activator)High arginine levelHigh protein diet and excessive degradationand the concentration of substrate and intermediates
146
Blood creatinine in pregnancy
decreased
147
arginine supplement for argininosuccinate lyase deficiency
it generates more ornithine for urea cycle to continue.also, catalyzes the production of N-acetylglutamate so acceelerates CPSI
148
The two main purposes for the transport of alanine to the liver
1- removal of nitrogen through the urea cycle2- glucogeogenesis
149
1---- + 2----- -(glutamine synthetase)--> glutamine + ADP Muscle and peripheral tissue
glutamineRequired fro glutamine transport
150
objFate of carbon core of amino acid depends on the nutritional state of the body.Fate of Carbon core of aa in the fed state:
Energy storageThe carbon of the excess amino acids will be converted to:1- glucose --> Glycogen2-acetylCoa --> TAG
151
objFate of carbon core of amino acid depends on the nutritional state of the body.Fate of Carbon core of aa in the fasting state
Energy productionCo2pyruvateTCA int.Acetyl CoA- Acetoacetate
152
What is common to both the fed and fasting states with respect to the fate of the carbon core of aa:
In both, amino acids are constantly used for the synthesis of physiologically important metabolites - proteins and hormones
153
obj ketogenic amino acids
leucine, lysine
154
objglucogenic aa
non essentialsAlaArgAsnAspCysGluGlnGlyPro Seress. aa.HisMetThrVal
155
Objnoess. aa.
AlaArgAsnAspCysGluGlnGlyPro SerTyrosine ( glucogenic and ketogenic)The rest are glucogenic
156
objthe glucogenic noess. aa.
AlaArgAsnAspCysGluGlnGlyPro Ser
157
objthe glucogenic and ketogenic noess aa.
tyr
158
objthe glucogenic and ketogenic ess.aa.
ThrIsoPheTrp
159
objconditionally ess. aa.
tyr, Arg, Cys
160
objThe surplus of cystine (cond. ess. aa.) comes from
met (ess, glucogenic)
161
objTyr (cond. ess. aa./ glucogenic and ketogenic) is produced from
phenyl-alanince (gluco-ketogenic)
162
objConditionally essential Arg
Arg is not ess. for adults, byt it is ess. for children
163
the aa that is ess for only children
Arg
164
Tyr production
Tyr is produced by the hydroxylation of phenyl-alanine
165
the source for carbon cores of 10-essentional aa.
glucose
166
ObjThe 10 ess. aa
Glucogenic: His, Met, Thr, Val.Gluco/Keto: Thr, ILe, Phe, TrpKet: leu, Lys
167
All the ketogenic aa. are
essentionalLeu, Lys
168
aa. syn. f. glycolysis int.
Cys, Gly, Ser, Ala
169
aa syn. f. OxA
Asp, Asn
170
aa. syn. f. a-ketoglutrate
Glu, Gln, Pro, Arg
171
The lonely aa.(an amino acid that is not produced via any three common pathways: f. OxA, F. a-ketoglutrjate and f. gly int.)
tyrosine, which is produced by the hydroxylation of phenylalanine.
172
Coenz. fo. transamination (TA) and deamination (DA)
pyridoxal-phosphate (B6)
173
B6
pyridoxal phosphate- a conenzyme for deamination and transamination
174
Coenz. fo. metabolism of Ser, Gly, Met, His
Tetrahydrofolate (folate)
175
Tetrahydrofolate
coenzyme fo. metabolism of gly, his, met, ser
176
cobalamins
B12 (Met metabolism conezyme)
177
B12 as a conenzyme
B12- Cobalamins is a conezyme for methionine metabolism
178
BH4
tetra-hydro.biopterin
179
tetrahydrobipterin is synthesized from
GTP
180
Tetrahydrobiopterine (BH4) is a conezyme for
hydroxylation of phenylalanine, tyr and trp
181
Hydroxylation of Phe, Tyr, Trp iis assisted by this coenzyme
BH4- tetrahydrobioptrein
182
The coenzyme for oxidative decarboxylation of BCAA
Thiamine-Pyrophosphate (B1) and lipoate
183
Thiamine-pyrophosphate and lipoate are common coenzymes for
oxidative decarboxylation of BCAA.thiamine-pyrophosphate is B1
184
Other names for B1, B6 and B12
B1- thiaminepyrophosphateB6- pyridoxal phosphateB12 cobalamins
