<p> Understanding enzyme catalysis is one of the major goals in biology. Ribonuclease A (RNase A) is a key system to understanding protein structure and function provides an attractive system to investigate the catalytic role of active site interactions. Crystal structures show a lysine residue (Lys41) situated in the RNase A active site, and mutagenesis studies suggest this residue is important for catalysis. To evaluate the catalytic importance of the Lys41-phosphate interaction, double mutant cycle analysis was used. Individual mutation of lysine to arginine (K41R) and substitution of a phosphate oxygen with sulfur led to ∼350 and ∼100-fold decrease in <i> k<sub>cat</sub>/K</i><sub>M</sub>, respectively. However, in the K41R background, substitution of the same oxygen with sulfur decreased activity by a similar amount (within 2-fold) as it did with the wild-type enzyme. This result provides evidence that functional interaction between Lys41 and the phosphate backbone of RNA substrates may not be solely limited between the two groups.</p><p>
| Identifer | oai:union.ndltd.org:PROQUEST/oai:pqdtoai.proquest.com:10603029 |
| Date | 31 August 2017 |
| Creators | Alade, Ayoade Nathaniel |
| Publisher | California State University, Long Beach |
| Source Sets | ProQuest.com |
| Language | English |
| Detected Language | English |
| Type | thesis |
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