PDBsum entry 4htk

Hydrolase

PDB id: 4htk

Contents

Protein chain

129 a.a.

Ligands

EDO ×3

Metals

_CL ×8

_NA

Waters ×175

PDB id:

4htk

Name:

Hydrolase

Title:

Mitigation of x-ray damage in macromolecular crystallography by submicrometer line focusing; total dose 2.17 x 10e+12 x-ray photons

Structure:

LysozymE C. Chain: a. Synonym: 1,4-beta-n-acetylmuramidasE C, allergen gal d iv. Ec: 3.2.1.17

Source:

Gallus gallus. Bantam,chickens. Organism_taxid: 9031

Resolution:

1.20Å R-factor: 0.134 R-free: 0.152

Authors:

N.E.C.Duke,Y.Z.Finfrock,E.A.Stern,R.W.Alkire,K.Lazarski,A.Joachimiak

Key ref:

Y.Z.Finfrock et al. (2013). Mitigation of X-ray damage in macromolecular crystallography by submicrometre line focusing. Acta Crystallogr D Biol Crystallogr, 69, 1463-1469. PubMed id: 23897469 DOI: 10.1107/S0907444913009335

Date:

01-Nov-12 Release date: 15-May-13

Protein chain

P00698  (LYSC_CHICK) -  Lysozyme C from Gallus gallus

Seq: 147 a.a.

Struc: 129 a.a.

Enzyme reactions

• Enzyme class: E.C.3.2.1.17 - lysozyme.
• Reaction: Hydrolysis of the 1,4-beta-linkages between N-acetyl-D-glucosamine and N-acetylmuramic acid in peptidoglycan heteropolymers of the prokaryotes cell walls.

DOI no: 10.1107/S0907444913009335

Acta Crystallogr D Biol Crystallogr 69:1463-1469 (2013)

PubMed id: 23897469

Mitigation of X-ray damage in macromolecular crystallography by submicrometre line focusing.

Y.Z.Finfrock, E.A.Stern, R.W.Alkire, J.J.Kas, K.Evans-Lutterodt, A.Stein, N.Duke, K.Lazarski, A.Joachimiak.

ABSTRACT

Reported here are measurements of the penetration depth and spatial distribution of photoelectron (PE) damage excited by 18.6 keV X-ray photons in a lysozyme crystal with a vertical submicrometre line-focus beam of 0.7 µm full-width half-maximum (FWHM). The experimental results determined that the penetration depth of PEs is 5 ± 0.5 µm with a monotonically decreasing spatial distribution shape, resulting in mitigation of diffraction signal damage. This does not agree with previous theoretical predication that the mitigation of damage requires a peak of damage outside the focus. A new improved calculation provides some qualitative agreement with the experimental results, but significant errors still remain. The mitigation of radiation damage by line focusing was measured experimentally by comparing the damage in the X-ray-irradiated regions of the submicrometre focus with the large-beam case under conditions of equal exposure and equal volumes of the protein crystal, and a mitigation factor of 4.4 ± 0.4 was determined. The mitigation of radiation damage is caused by spatial separation of the dominant PE radiation-damage component from the crystal region of the line-focus beam that contributes the diffraction signal. The diffraction signal is generated by coherent scattering of incident X-rays (which introduces no damage), while the overwhelming proportion of damage is caused by PE emission as X-ray photons are absorbed.