CH 461 Lecture Notes - Lecture 26: Thioredoxin Reductase, Ribonucleotide Reductase, Thymidylate Synthase
Document Summary
The enzyme dna polymerase, which uses deoxynucleoside triphosphates as substrates, makes dna. To ensure enough precursors for dna synthesis, two reactions must occur. First, the 2 position of the ribose ring of ribonucleotides must be reduced from a c oh to a c h before the nucleotides can be used for dna synthesis. Secondly, the thymine ring must be made by addition of a methyl group to uridine. Ribonucleotide reductase uses ribonucleoside diphosphates (adp, gdp, cdp, and. Udp) as substrates and reduces the 2 position of ribose. The small protein thioredoxin supplies reducing equivalents to ribonucleotide reductase for the ribose ring reduction. Thioredoxin is itself reduced by another protein, thioredoxin reductase, a flavoprotein. Reduced glutathione can also carry reducing equivalents to ribonucleotide reductase. In both cases, the ultimate source of reducing equivalents is. The regulation of ribonucleotide reductase is complex, with many feedback reactions used to keep the supplies of deoxynucleotides in balance.
