Nucleotide and Heme Catabolism Flashcards
What is the common catabolic product produced by adenosine and guanosine catabolism that is the substrate for generation of uric acid?
Xanthine
Final product of catabolism of cytidine and uridine is?
Acetyl-CoA
How are catecholamines inactivated? (Remember: what are catecholamines)
What enzyme catalyzes this?
Catecholamines are neurotransmitters–LDOPA derivatives
Oxidation–catalyzed by monoamine oxidase
Methylation–catalyzed by catechol-O-methyltransferase (COMT)
What enzymes degrade nucleic acids into oligonucleotides?
Nucleases
What enzymes degrade DNA?
DNases
Cleave the sugar-phosphate backbone
What enzymes degrade RNA?
RNases
What enzymes cleave oligonucleotides to generate mononucleotides?
Phosphodiesterases
Also cleaves the sugar phosphate backbone
What enzymes remove phosphate from nucleotides to make nucleosides?
Nucleotidases
What enzymes cleave nucleotides to generate bases and sugars?
Nucleosidases
cleaves glycosidic bond
How is AMP catabolized?
AMP must be converted to xanthine–2 paths
1) deamination to generate IMP -> nucleotidase converts IMP to inosine
2) Nucleotidase cleaves to generate adenosine -> deaminated to inosine
Inosine cleaved by nucleosidase to produce hypoxanthine
Xanthine oxidase converts hypoxanthine to xanthine
How is GMP catabolized?
GMP must be converted to xanthine
1) nucleotidase generates guanosine
2) nucleosidase generates guanine
3) deamination of guanine produces xanthine
XMP must be converted to xanthine
1) nucleotidase generates xanthosine
2) nucleosidase generates xanthine
Xanthine oxidase converts xanthine to uric acid
AMP deamination to IMP pathway occurs in what tissues? How is AMP catabolized in other tissues?
Muscle
In other tissues, goes through adenosine
Why are there 2 AMP catabolism pathways?
The deamination pathway has a branching point in the muscle: IMP can react with aspartate to produce fumarate, which enters citric acid cycle–important to generate more energy
What is uric acid?
End product of purine catabolism for humans and some other animals–primates and birds
Humans can’t break down the ring
What is gout?
Disease caused by high uric acid levels
Uric acid can form crystals–causes inflammation, joint damage, arthritis, kidney malfunctions, tophi (uric acid deposits under the skin)
