Abstract
The fluorescent reagent 9-anthroylnitrile (ANN) reacted preferentially with serine among various amino acids tested. When the myosin subfragment-1 (S-1) was incubated with ANN, the 9-anthroyl (AN) group was covalently incorporated into the S-1 heavy chain. The incorporation of the AN group was enhanced by the presence of ATP and ADP. In the presence of ATP, 0.98 mol of the AN group was maximally incorporated into S-1. The resulting S-1 derivative exhibited four absorption maxima in the range of 300-400 nm and fluoresced strongly with an emission maximum at 462 nm upon excitation at 390 nm. The spectral properties were similar to those of the AN-derivatives of serine and polyserine. When 0.98 mol of the AN group was incorporated into S-1, the K+- and Ca2+-ATPase activities decreased to 30%, while the Mg2+-ATPase activity increased to 220% of the original value. Tryptic digestion of the labeled S-1 revealed that the AN group was attached only to the NH2-terminal 23-kDa tryptic peptide of the S-1 heavy chain. Neither the 20-nor the 50-kDa peptide was labeled with ANN. The results suggest that a serine residue, which becomes more reactive in the presence of the nucleotide, is located in the 23-kDa tryptic peptide of S-1.
Highlights
The fluorescent reagent 9-anthroylnitrile (ANN) re- SH2 areclose to both th2e3- and 50-kDa peptides, suggesting acted preferentially with serineamong various amino that all three tryptic peptides of S-1 are contiguous around acids tested
Several with ATP hydrolysis by myosin ATPase is the most essential fluorescent reagents were further examined in an attempt to process of muscle contraction
Localization of the AN Group Incorporated into S-1"To ascertain to which tryptic peptide of the S-1heavy chain the AN group binds covalently, we studied the limited cleavage of AN-S-1 by trypsin
Summary
From the Departmentof Chemistry, Asahikawa MedicalCollege, Asahikawa, Hokkaido, Japan. The fluorescent reagent 9-anthroylnitrile (ANN) re- SH2 areclose to both th2e3- and 50-kDa peptides, suggesting acted preferentially with serineamong various amino that all three tryptic peptides of S-1 are contiguous around acids tested. It has been proposed that the incubated with ANN, the 9-anthroyl (AN) group was myosin ATPase site is likely to include parts of the three covalently incorporated into the S-1 heavy chain. Myosin subfragment-1 (S-1)’ label the 23-kDa peptide selectively. Isthe globularhead region of the myosin molecule which The 23-kDa peptide of S-1 contains oneof the most concontainsthesites responsiblefor the ATP hydrolysis and served sequences along the heavy chain [24, 25]. A hydroxyl group-specific reagent may be capable of labeling the 23-kDa peptide selectively for all themyosin heavy chains. Our results suggest that ANN reacts preferentially with a serine residue in the23-kDa peptide when ATP (ADP) is present
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
