Novel labeling strategy for structural measurements in proteins via 2-D IR spectroscopy

PHYS 333

Sri Ram G Naraharisetty, snaraha@tulane.edu1, Valeriy M Kasyanenko, vkasyane@tulane.edu1, Joerg Zimmermann, jzimm@scripps.edu2, Megan Thielges2, Floyd E Romesberg, floyd@scripps.edu2, and Igor V. Rubtsov, irubtsov@tulane.edu1. (1) Department of Chemistry, Tulane University, RM # 2015, Steren Hall, 6400 Freret Street, New Orleans, LA 70118, (2) Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037
Availability of convenient vibrational labels is essential for applying 2DIR spectroscopy to study structures of proteins. We show that deuterated amino acid side groups form convenient labels for 2DIR measurements. Dual-frequency 2DIR measurements were performed on Boc-leucine-d10 and leucine-d10 methyl ester hydrochloride amino acids. The (CD, amide-I) and (CD, amide-II) cross peaks have been measured. The couplings of the CD transitions with amide-I and amide-II modes have been determined and the relative orientation of their transition moments have been measured. Relaxation-assisted 2DIR cross-peak measurements enhanced several very weak CD features and allowed assignment of specific CD groups in the peptide. Diagonal CD measurements helped further in assigning the CD band transitions. Thus we have demonstrated that deuteration of the side chains of leucine amino acid forms a universal structural reporter, which can be used in combination with other label, such as 13C=18O.
 

PHYS Poster Session - Optical Probes of Dynamics in Complex Environments
7:30 PM-10:00 PM, Wednesday, April 9, 2008 Morial Convention Center -- Hall A, Poster

Sci-Mix
8:00 PM-10:00 PM, Monday, April 7, 2008 Morial Convention Center -- Hall A, Sci-Mix

Division of Physical Chemistry

The 235th ACS National Meeting, New Orleans, LA, April 6-10, 2008