N-Phenylnaphthalen-1-amine

N-phenylnaphthalen-1-amine (NPN) is a nonpolar, hydrophobic molecule with the chemical formula C₁₆NH₁₃. This molecule is most notable for its binding affinity in mouse major urinary protein (MUP). This ligand has the greatest binding affinity of all MUP binding ligand discovered, including 2-sec-butyl-4,5-dihydrothiazole (SBT), 6-hydroxy-6-methyl-3-heptanone (HMH), and 3-isobutyl-2-methoxypyrazine (IBMP). NPN binds 28 times tighter than SBT. It also makes 38 nonpolar contacts to MUP, whereas IBMP only makes 15 contacts which are the next most nonpolar contacts.^[1] There is a slight difference in the binding affinities and forms for NPN bound in wild-type MUP and the Y120F MUP mutant. In wild-type MUP there is just enough room for the anime group of NPN to makes a water mediated hydrogen bond to Tyr120, whereas in Y120F MUP mutant, there is a slight shift and the amine group makes a direct hydrogen bond to Tyr120. Much is still unknown about the entropic and enthalpic effects of the MUP binding site.^[2]

References

1. ^ Pertinhez, Thelma A.; Ferrari, Elena, Casali, Emanuela, Patel, Jital A., Spisni, Alberto, Smith, Lorna J. (1 December 2009). "The binding cavity of mouse major urinary protein is optimised for a variety of ligand binding modes". Biochemical and Biophysical Research Communications 390 (4): 1266–1271. doi:10.1016/j.bbrc.2009.10.133. http://www.sciencedirect.com.ezproxy.lib.utexas.edu/science/article/pii/S0006291X0902124X. 
2. ^ Homans, SW (2007 Jul). "Water, water everywhere--except where it matters?". Drug discovery today 12 (13-14): 534-9. PMID 17631247. http://www.mendeley.com/research/water-water-everywhereexcept-it-matters-1/.