Effects of distal pocket mutations on the nitrite reductase of sperm whale myoglobin

• Main Author: Lea Cassandra Lough
• Other Authors: Raymond Esquerra, George Gassner, Anton Guliaev
• Format: Master Thesis
• Language: English
• Published: San Francisco State University 2012
• Subjects: Sperm whale
• Online Access: http://hdl.handle.net/10211.3/122352

The nitrite reductase activity of heme proteins plays key roles in physiology by producing nitric oxide under hypoxic conditions. Many heme proteins exhibit the ability to convert nitrite to nitric oxide at different rates that appear to reflect the protein environment of the heme moiety. We hypothesized that His 64 mutations to alanine (H64A), valine (H64V), leucine (H64L), and glutamine (H64Q) will alter the nitrite reductase rate by preventing the hydrogen bond to HNO2 . We also proposed that a decrease in distal pocket size with Leu 29 mutations to phenylalanine and tryptophan will decrease the rate of the reaction by limiting the accessibility of nitrite to the heme. To test these hypotheses, we spectrophotometrically measured the nitrite reductase activity of these mutants.