Term
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Definition
• Functions directly as a neurotransmitter- acts to
block impulses traveling in the spinal cord to
stimulate skeletal muscle
• Conjugated to cholesterol derivative to form
glycocholic acid (bile salt)
• Incorporated directly during de novo synthesis of
purines
• Condenses with succinyl-CoA in first step of heme
biosynthesis |
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Term
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Definition
• Along with glutamine, a
predominant circulating
amino acid
• Transports amino groups
from muscle to liver
(transamination from
muscle pyruvate) in a
process called the glucosealanine
cycle |
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Term
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Definition
• Source of one-carbon fragments (folate derivatives) used in biosynthesis
The Enetial source of carbon in Carboxylation |
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Term
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Definition
• Transporter of amino groups; serves as a form of activated ammonium ions; source of
NH4+ in kidney
• Amino group donor in purine biosynthesis
• Amino group donor in Biosynthesis of amino sugars |
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Term
Amino Sugar Biosynthesis
3 |
|
Definition
• Fructose-6-P + glutamine
• Glucosamine-6-P + glutamate
• All other amino sugars are derived
from glucosamine-6-P |
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Term
|
Definition
- Neurotransmitter - glutamate is the primary neurotransmitter in the central nervous system - acts on both ion channels and G-coupled receptors
- Source of γ-amino butyrate
(GABA) via decarboxylation of the α-carboxyl. GABA is the major inhibitory transmitter in the brain; the GABA receptor is the target of enzodiazepines/barbiturates
- Participant in transaminations - glutamate is the source of amino groups for most other amino acids
- Activated Glutamate is a Reactant in ammonia fixation, which results in the production of glutamine
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Term
|
Definition
• Activated by reaction with ATP to form S-adenosyl methionine (SAM)- source of methyl groups for most methylation reactions
• SAM can be decarboxylated to leave a propylamine residue attached to the sulfur - precursor of spermine and spermidine
(“polyamines”) |
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Term
|
Definition
• Immediate precursor of urea production via action of arginase in urea cycle.
• Source of NO, a second essenger |
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Term
| Formation fo creatine/creatine phosphate |
|
Definition
Glycine, arginine, and
methionine all
contribute to the
synthesis of creatine
and phosphocreatine |
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Term
|
Definition
| • Decarboxylation produces histamine - a major stimulant of acid release in the stomach and in systemic reactions to allergens |
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Term
Phenylalanine and Tyrosine
4 |
|
Definition
• Under normal conditions, phenylalanine is a dietary essential amino acid, but tyrosine is not since it is produced from phenylalanine:
uses tetrahydrobiopterin
• Tyrosine is a precursor of several important molecules: dopa
dopamine, and epinephrine/norepinephrine
• Tyrosine is a precursor of thyroxine/T3
• In addition, melanin is derived by oxidation of dopa catalyzed by tyrosinase |
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Term
|
Definition
• Provides electrons for reduction of oxygen in hydroxylation of phenylalanine- regeneration
requires specific reductase
• Deficiency of phenylalanine hydroxylase (phenylketonuria, PKU) is usually screened for at
birth (blood sample to measure elevated phenylalanine levels) - controllable by specialized diet with limited phe, and tyr supplementation - less required by puberty
• Deficiency of the biotperin reductase is more severe and cannot be controlled by dietary means |
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Term
|
Definition
• Intermediate in synthesis of
epinephrine/norepinephrine as well as a neurotransmitter - involved in control of voluntary movement (Parkinson’s disease).
Formed by decarboxylation of dopa. Both epinephrine and norepinephrine are neurotransmitters and signaling molecules (fight or flight response - sympathetic nerves) |
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Term
|
Definition
• Hydroxylation (5-position) followed by decarboxylation yields serotonin, a multi-faceted
neurotransmitter. The Hydroxylation step requires
Biopterin cofactor; carboxylation step requires PLP cofactor.
• Some tryptophan can be degraded to nicotinic acid (precursor for NAD+) but this usually is insufficient to eliminate dietary need. |
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Term
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Definition
| Cofactor in carboxylation and decarboxylation |
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