Nakata S, Eiki T, Tanaka N, Koyama T, Tsukui H, Watanabe S
J Biochem. 1986 Jan;99(1):27-32. doi: 10.1093/oxfordjournals.jbchem.a135470.
When trinitrophenyl (TNP) myosin of either chicken breast muscle or porcine cardiac muscle was left to stand in an alkaline medium at 20 degrees C for several hours, nitrite ions were found to be gradually produced. The nitrite production from myosin trinitrophenylated in the presence of PPi occurred at the same rate and to the same extent as that from myosin trinitrophenylated in the absence of PPi. The nitrite production was significantly reduced when thiols of myosin were modified with 2-nitro-5-thiocyanobenzoate. Four different preparations of TNP subfragment-1, S1(Aa), S1(Ab), S1(Ba), and S1(Bb), were obtained from chymotryptic digest of chicken breast myosin trinitrophenylated in the absence of PPi. When these preparations of TNP-S1 were left to stand at alkaline pH, a significant amount of nitrite was produced from S1(Ab) and S1(Bb), but very little from S1(Aa) and S1(Ba). In our previous report (J. Biochem. 97, 965-968, 1985), S1(Aa) and S1(Ba) were suggested to correspond to "non-burst" heads of myosin, and S1(Ab) and S1(Bb) to "burst" heads of the myosin molecule (Inoue et al. (1980) Adv. Biophys. 13, 1-194). Therefore, the present findings described above strongly suggest that the nitrite production involves some interaction of TNP groups with thiols, and that it occurs at the "burst" heads.
当鸡胸肌或猪心肌的三硝基苯基（TNP）肌球蛋白在20℃的碱性介质中放置数小时后，发现亚硝酸根离子会逐渐产生。在有焦磷酸（PPi）存在的情况下三硝基苯基化的肌球蛋白产生亚硝酸根的速率和程度，与在没有PPi时三硝基苯基化的肌球蛋白相同。当肌球蛋白的巯基用2-硝基-5-硫氰基苯甲酸修饰后，亚硝酸根的产生显著减少。从在没有PPi的情况下三硝基苯基化的鸡胸肌肌球蛋白的胰凝乳蛋白酶消化物中，获得了四种不同的TNP亚片段-1制剂，即S1（Aa）、S1（Ab）、S1（Ba）和S1（Bb）。当这些TNP-S1制剂在碱性pH下放置时，S1（Ab）和S1（Bb）会产生大量的亚硝酸根，但S1（Aa）和S1（Ba）产生的很少。在我们之前的报告（《生物化学杂志》97，965 - 968，1985）中，S1（Aa）和S1（Ba）被认为对应于肌球蛋白的“非爆发”头部，而S1（Ab）和S1（Bb）对应于肌球蛋白分子的“爆发”头部（井上等人（1980年）《生物物理学进展》13，1 - 194）。因此，上述目前的发现强烈表明，亚硝酸根的产生涉及TNP基团与巯基的某种相互作用，并且它发生在“爆发”头部。
