Skip Navigation

This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Request Permissions
Google Scholar
Right arrow Articles by IKEDA, K.
Right arrow Articles by AMANO, T.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by IKEDA, K.
Right arrow Articles by AMANO, T.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

J. Biochem, 1967, Vol. 62, No. 3 315-320
© 1967 Japanese Biochemical Society

research-article

Effect of pH on the Ultraviolet Optical Rotatory Dispersion and Circular Dichroism of Lysozyme*

KIYOSHI IKEDA{dagger}, KOZO HAMAGUCHl{dagger}, MICHIKO IMANISHl{ddagger} and TSUNEHISA AMANO{ddagger}

{dagger}From the Department of Chemistry, Faculty of Science, Kwansti Gakutn University Nishinomiya
{ddagger}the Department of Immunochemtstry, Research Institute for Microbial Diseases Osaka University Osaka

In order to clarify the state of the tyrosyl and tryptophyl residues of hen and duck egg-white lysozymes [mucopeptide N-acetylmuramyl-hydrolase, EG 3.2.1.17 [EC] ], ultraviolet optical rotatory dispersion (ORD**) and circular dichroism (CD)** were measured. The CD spectrum of both lysozymes in a neutral solution had a positive band at 288 mµ and a negative band at 268 mµ. At alkaline pH, the maximum of the band at 288 mµ was shifted to 298 mµt. At pH above pH 12, however, the CD band at 298 mµ decreased with time and finally disappeared. Spectrophotometric titration of the tyrosyl groups and ORD measurement have shown that lysozyme is denatured on exposure to pH above 12 and one and two tyrosyl residues become titratable for hen and duck lysozyme, respectively. Therefore, it is suggested that the CD band at 298 mµ arises from ionized tyrosyl residues which locate on the surface of the lysozyme molecule and are dependent on the protein conformation.

On the other hand, a positive CD band was also observed around 250 mµ at alkaline pH. This band did not disappear on alkali denatu-ration. An approximately linear relation was obtained between the values of molecular ellipticity at the maximum of the CD band around 250 mµ and the number of ionized tyrosyl residues. Therefore, the CD band around 250 mµ depends mainly on the number of ionized tyrosyl residues and involves little conformational contribution. However, contribution of other side chains to the optical activity around 250 mµ must be also taken into account.

*"Structure of Lysozyme. XIII." For part XII of this series, see Ogasahara and Hama-guchi (l). This paper was presented at the Fifth Annual Meeting of the Biophysical Society of Japan, Kyoto, December 1966. This work was supported in part by the scientific research grant from the Ministry of Education.

** The abbreviations are; ORD: Optical rotatory dispersion, CD: Circular dichroism


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?




Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.