A short hydrophobic segment next to tryptophan-130 in myosin heavy chain is close to the ribose ring of ADP bound in the adenosinetriphosphatase site |
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Authors: | K Sutoh |
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Institution: | Department of Biophysics and Biochemistry, Faculty of Science, University of Tokyo, Japan. |
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Abstract: | The ATPase site of rabbit skeletal myosin was covalently labeled by an ADP analogue that carried a biotin moiety on its adenine ring and a photoreactive phenyl azide group on its ribose ring Sutoh, K., Yamamoto, K., & Wakabayashi, T. (1986) Proc. Natl. Acad. Sci. U.S.A. 83, 212-216]. The ADP analogue was tightly trapped into the ATPase site in the presence of vanadate ions and then covalently cross-linked to the site by UV irradiation. The N-terminal 23,000-dalton tryptic fragment of the heavy chain was selectively labeled with the analogue. Further mapping of the labeled segment along the 23-kDa fragment was carried out by "end-label fingerprinting" which employed site-directed antibodies against both ends of the N-terminal heavy chain fragment. The mapping revealed that a hydrophobic segment of approximately 10 residues next to Trp-130, which was reported to be in proximity to the adenine ring of ADP bound to the ATPase site Okamoto, Y., & Yount, R. G. (1985) Proc. Natl. Acad. Sci. U.S.A. 82, 1575-1579], was the site of covalent labeling with the ADP analogue. The result indicates that the hydrophobic segment is close to the ribose ring of ADP bound to the ATPase site. |
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