Precession Method used in Orientation for Single Crystals of L-lys HCl 2H2O and L-arg HCl H2O

Yiying Zhou

Department of Physics and Astronomy

Georgia State University

Outline

• What are we study in EPR lab ?

• Why choose lysine and arginine?

• Precession method used in orienting the crystal of l-lys Hcl 2H2O and l-arg Hcl H2O

What are we studying in the EPR lab?

1) How to detect the free radicals?

• EPR technique is the only analytical technique to measure free radical

2) Why use single crystals?

• Single crystals permits taking full advantage of the ESR technique for purposes of radical identification .

• The structure information about the molecules and their surroundings can be provided by Crystallography

Monoclinic labeling to space group of P21 and there are two molecules in

each unit cell.

Molecular Structure of L- arg HCl H2O

Unit cell parameters a = 11.044Å b = 8.481Å c = 11.214 Å ß = 91.31

Unit cell parameters: a = 11.044Å b = 8.481Å c = 11.214 Å ß = 91.31

Molecular Structure of L- lys HCl 2H2O

Monoclinic labeling to space group of P21

and there are two molecules in each unit cell.

Distribution of Hydrogen bonds according to the participating amino acids and DNA base or backbone group

It is important to properly locate and assign the axis of crystal

• The systems of crystal are anisotropic and thus the magnitude of hyperfine coupling constants, the important magnetic parameters to assign the free radicals, depend strongly on orientation in external magnetic field.

• In order to calculate the hyperfine coupling constants (which are generally described by eigenvalues and eigenvectors or tensor) from ENDOR data, it is necessary to take ESR and ENDOR data at lease at two different crystal lattice planes, which means rotate the crystal with two certain different axes and scan the external magnetic field in the plane perpendicular to the rotation axis respectively.

Principle of Precession Method:

• 1) Bragg law:

N = 2d sin

• 2) Ewald Construction

OP = 1/d410 = (2/ ) sin

3) Precession method

Photos of layer screen and Cirle

Circle Layer screen

Sin = (1)

F

t 2/

t = F (2)

hkld

Procession Camera

F = 60 mm = 0.7107Å

Diffraction Pattern for single crystal of l-lys Hcl 2H2O

(2) (1) (3)

Diffraction pattern for Single crystal of l- arg HCl H2O

(1) (2) (3)

Table 2 Spacing of Diffaction Pattern

Table 1 Parameter of Unit Cell

Table 3.Comparison of Results of line3

l-lys Hcl 2H2O

d3 = t3 / (60mm

0.7107 Å) (Å-1)

d32

(Å-1)2

d32 = (ha*)2 + (kb*)2 +

(lc*)2 (Å-1)2

Layer 1 0.1540 0.0237 0.0238 (110)*

Layer 2 0.1554 0.0241 0.0238 (110)*

Layer3 0.2286 0.0523 0.0523 (021)*

l-argHCl H2O

d3 = t3 / (60mm

0.7107 Å) (Å-1)

d32

(Å-1)2

d32 = (ha*)2 + (kb*)2 +

(lc*)2 (Å-1)2

Layer1 0.1498 0.0224 0.0222(110)*

Layer2 0.1485 0.0220 0.0218(011)*

Layer3 0.1488 0.0221 0.0218(011)*

Crystal transferring

Reference

• 1) Luscombe, N, M.; Roman, A.L; Nucleic Acids Research, 2001, 29,

• 2860

• 2) Dow, J; Jeansen, L. H.; Acta Cryst., 1970, B26, 1662

• 3) R.R. Bugayong; A. Sequeira; Acta Cryst., 1972, B28, 3214

• 4)  A. Ducruix; R. Giege; Crystallization of Nucleic Acids and

• Proteins; 1992 Oxford University Press.

• 5) Martin J. Buerger; The Procession Method in x-ray crystallograph;

• John Wiley and Sons, Inc

• 6) John A. Weil; James R. Bolton; Electron Paramagnetic Resonance;

• 1994 John Wiley & Sons, Inc.

Thanks