Electrical conductivity of single crystals of lysozyme

✍ Scribed by Mitsuo Ataka; Shoji Tanaka

• Publisher: Wiley (John Wiley & Sons)
• Year: 1980
• Tongue: English
• Weight: 623 KB
• Volume: 19
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.1980.360190315

✦ Synopsis

Abstract

The dc electrical conductivity of large single crystals of hen egg‐white lysozyme has been measured. The samples were grown from aqueous solution and dried in air with silica gel. The temperature dependence of the conductivity obeyed the relation σ = σ~0~ exp(− Δ__E__/kT), with Δ__E__ = 1.2 eV. The Δ__E__ value agreed with most of the previous results for various proteins in the form of lyophilized powder. On the other hand, log σ~0~, being between 7 and 11, was much larger than the previously reported values and differed among the samples. An irreversible decrease in σ~0~, without affecting Δ__E__, was observed on heating the samples above 85°C. It was shown that the set of results can be explained if the charge carriers responsible for the observed conduction are regarded as protons, originating from residual water molecules. Photoresponse of the samples to uv radiation below 305–315 nm was also observed. Reproducible and reliable results were obtained relatively easily in the present experiments, which is thought to be the main advantage of using single‐crystalline samples.