This basic science study identifies Trp-130 as the primary residue at the active site of skeletal myosin that interacts with the purine ring of ATP.
The active site of skeletal myosin has been photoaffinity labeled (approximately equal to 50%) by the ADP analog N-(4-azido-2-nitrophenyl)-2-aminoethyl triphosphate (NANDP) following the cobalt phenanthroline active site trapping procedure of Wells and Yount Wells, J. A. & Yount, R. G. (1979) Proc. Natl. Acad. Sci. USA 76, 4966-4970. Extensive proteolytic digestion of 3HNANDP-labeled myosin subfragment one yielded two major peptides, P1 and P2, which were purified by reversed-phase high-performance liquid chromatography. These peptides represented 50% of all labeled amino acids and contained 1 mol of the unusual amino acid epsilon-N-trimethyllysine. Analysis of P2 by Edman techniques gave a sequence Val-Asn-Pro-Tyr-Lys(Me3)-X-Leu-Pro-Val-Tyr, which corresponds to an identical sequence for residues 125-134 determined by Tong and Elzinga Tong, S. W. & Elzinga, M. (1983) J. Biol. Chem. 258, 13100-13110 for a segment of rabbit skeletal myosin heavy chain in which X is Trp-130. P1 was identical to P2 except it contained an additional three amino acids, Asn-Pro-Gln, at the COOH-terminal end. Amino acid composition, sequence data, spectral measurements, and location of radioactive label in both P1 and P2 all indicate Trp-130 is the major site of labeling by NANDP. The adjacent epsilon-N-trimethyllysine may provide part of the binding site for the triphosphate portion of ATP.
Okamoto et al. (Fri,) studied this question.