TY - JOUR
T1 - Characterization of the active site of platelet myosin in comparison to smooth and skeletal muscle myosin
AU - Cohen, Isaac
AU - Kaminski, Elizabeth
AU - Lamed, Raphael
AU - Oplatka, Avraham
AU - Mühlrad, Andras
PY - 1976/7
Y1 - 1976/7
N2 - Heavy meromyosin subfragment-1 from human platelets and chicken gizzard exhibited an identical chromatographic pattern on agarose-ATP columns both in the absence and in the presence of Ca2+ and Mg2+. In the presence of Ca2+, the behavior differed from that of rabbit white skeletal muscle subfragment-1. The reaction of lysyl residues of platelet myosin with 2,4,6-trinitrobenzene sulfonate did not affect the K+- or Mg2+-stimulated ATPase activity. A similar behavior was exhibited by chicken gizzard myosin whereas trinitrophenylation of the more active lysyl residues in skeletal muscle myosin caused a marked increase in Mg2+-stimulated and a decrease in K+-stimulated ATPase activity. These features may point to a similar location of the essential lysyl residue in platelet and smooth muscle myosin, which is different from that of skeletal muscle. Alkylation of thiol groups by N-ethyl maleimide in the absence of added nucleotides resulted in a loss of K+-ATPase and in an increase in the Ca2+-ATPase in all three myosins, the increase for the skeletal myosin being much greater than for the platelet and chicken gizzard preparations. Alkylation of myosin in the presence of MgADP led to a decrease in K+-ATPase of all preparations whereas the Ca2+-ATPase as a function of time exhibited a maximum for the platelet and skeletal muscle proteins. These features may point to a certain similarity with respect to the active site of platelet and smooth muscle myosins and a difference between these and skeletal muscle myosin.
AB - Heavy meromyosin subfragment-1 from human platelets and chicken gizzard exhibited an identical chromatographic pattern on agarose-ATP columns both in the absence and in the presence of Ca2+ and Mg2+. In the presence of Ca2+, the behavior differed from that of rabbit white skeletal muscle subfragment-1. The reaction of lysyl residues of platelet myosin with 2,4,6-trinitrobenzene sulfonate did not affect the K+- or Mg2+-stimulated ATPase activity. A similar behavior was exhibited by chicken gizzard myosin whereas trinitrophenylation of the more active lysyl residues in skeletal muscle myosin caused a marked increase in Mg2+-stimulated and a decrease in K+-stimulated ATPase activity. These features may point to a similar location of the essential lysyl residue in platelet and smooth muscle myosin, which is different from that of skeletal muscle. Alkylation of thiol groups by N-ethyl maleimide in the absence of added nucleotides resulted in a loss of K+-ATPase and in an increase in the Ca2+-ATPase in all three myosins, the increase for the skeletal myosin being much greater than for the platelet and chicken gizzard preparations. Alkylation of myosin in the presence of MgADP led to a decrease in K+-ATPase of all preparations whereas the Ca2+-ATPase as a function of time exhibited a maximum for the platelet and skeletal muscle proteins. These features may point to a certain similarity with respect to the active site of platelet and smooth muscle myosins and a difference between these and skeletal muscle myosin.
UR - http://www.scopus.com/inward/record.url?scp=0017133522&partnerID=8YFLogxK
U2 - 10.1016/0003-9861(76)90505-1
DO - 10.1016/0003-9861(76)90505-1
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AN - SCOPUS:0017133522
SN - 0003-9861
VL - 175
SP - 249
EP - 255
JO - Archives of Biochemistry and Biophysics
JF - Archives of Biochemistry and Biophysics
IS - 1
ER -