Abstract

The effects of ultraviolet light on bacteriophage f2 were investigated to determine the inactivation kinetics and its mechanism. The 260nm light showed a little higher inactivation rate than the one of 300 nm. In this work, our main concern was whether structural and/or conformational changes in the protein capsid could occur by UV irradiation. The inactivation for the first 20 minutes irradiation was rapid with a loss of about 4 logs and followed by a slower rate during the next 40 minutes with no survival noted in the samples irradiated for 90 minutes or longer. The structural change of the protein capsid was examined by optical spectroscopic techniques and electron microscopy. The absorption spectra of the UV irradiated phages showed no detectable differences in terms of the spectral shape and intensity from the control phage. However, the fluorescence emission spectroscopic data, i.e. 1) fluorescence quenching of tryptophan residues upon irradiation of 300 nm light, 2) enhancement of fluorescence emission of ANS (8-aniline-1-naphthalene sulfonate) bound to the intact phages compared to the one in the UV-treated phages, and 3) decrease of energy transfer efficiency from tryptophan to ANS in the UV-treated samples, presented remarkable differences between the intact and UV-treated phages. Such a structural alteration was also observed by electron microscopy The UV-treated phages appeared to be broken and empty capsids. Therefore, the inactivation of the bacteriophage f2 by UV irradiation is thought to be attributed to the structural change in the protein capsid as well as damage in the viral RNA by UV irradiation.

Bacteriophage f2에 대한 자외광선의 살균효과와 외투막 단백질의 구조에 미치는 영향을 Ray-onet photoreactor PPR-208을 사용하여 300nm의 광선으로 연구하였다. 처음 20분간의 조사에서는 약 4 log의 phage가 감소되고 그후 완만한 살균효과를 보이다가 90분 이상의 조사에서는 생존 바이러스가 발견되지 않았다. Tryptophan residue의 fluorescenve quenching, 자외선으로 조신한 phage에 부착시킨 ANS (8-anilino-1-napht-halene sulfonate)의 fluorescence emission의 감소, tryptophan에서 ANS로의 energy transfer 의 감소 등 spectroscopic technique에 의한 결과와 자외선 조사에 의하여 단백질 외투만이 파손되는 전자현미경 관찰의 결과에 의하여 자외광선은 phage f2의 외투막 단백질의 구조에 변화를 일으킨다는 것이 밝혀졌다.

Keywords