BMB 401 Lecture 33 Flashcards

Nucleoside vs Nucleotide

Side: has sugar and base
TIde: has sugar, base, and phosphate(s)

How to name RIbonucleosides, RIbonucleoides,DeoxyrIbonucleosides,and Deoxyribonucleotides

Ribo'sides:add "osine" at end
Deoxy'sides: add "deoxy" in front and "osine" at end
Ribo'tides: add "ylate" at end
Dexy'tides: add "deoxy" in front and "ylate" at end

Purines vs Pyrimidines

Purines: 2 rings, A,G
Pyrimidines: 1 ring, C, U, T

Pyrimidine de novo pathway

1. Orotate synthesis (carbamoyl P + Asp)
2. Orotidylate
3. UMP
6. TTP & dCTP

Rate limiting step of pyrimidine de novo path

carbamoyl phosphate synthase II
-inhibited by UTP (pdt)
-activated by PRPP (substrate)

Purine de novo pathway intermediate

Inosine monophosphate

Purine de novo pathway intermediate 1st committed step

Glutamine Phosphoribosyl amidotransferase
-inhibited by AMP, ADP, GMP, GDP

AMP & GMP made from IMP
-P group from?
-Amino group from?

P from GTP, Amino from Asp
loss of fumarate
P group from ATP, Amino from ammonia from glutamine source

Purine Salvage pathway

Phosphoribosyl transferases (PRT) attach pre formed bases to
activated ribose, PRPP

2 Purine base transferases

1.APRT :adenine+ PRPP>AMP+PPi
2. HGPRT:guanine + PRPP> GMP + PPi, hypoxanthine + PRPP> IMP+PPI

Deficiency in HGPRT?

Lesch-Nyhan Syndrome
-self destructive

Thymidylate Biosynthesis

dUMP+ N5, N10 methylene tetra
hydrofolate>TMP+ dihydrofolate
Enzyme: thymidylate synthase

RIbonucleotide Reductase

Allosterically regualted
ATP activates, dATP deactivates