BIO SCI M114 Lecture Notes - Lecture 14: Glycosidic Bond, Transfer Rna, Leaving Group
12 Mar 2014
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Document Summary
Ionization of the nucleotides: though the pkas of the nucleotides are far from the normal conditions, they are critical for viruses that survive in those low-ph environments, thus those pkas may have a physiological significance in that context. Rna: don"t have to memorize all the different rna bases, can be modified extensively, we don"t find these modifications in mrna or rrna but mostly in trna, dihydrouridine: commonly found in trna. Atp & gtp: readily break down because of the highly-unfavorable (-4) charges, 7kcal per phosphate for gamma & beta (alpha is not, 13kcal/mol for each atp. In a later reaction the pyrophosphates are further hydrolyzed (releasing another. 7kcal: totaling 15kcal, can we think of this reaction as coupled, the enzymes does couple the energy reactions to help form the ii. phosphor-diester bond. It is important that this pyrophosphate is hydrolyzed further because this makes the polynucleotide synthesis irreversible, not allowing pyrophosphates to reform a tri-phosphate nucleotide.
