Osbahr A J, Custodio R
Am J Physiol. 1975 Feb;228(2):488-95. doi: 10.1152/ajplegacy.1975.228.2.488.
Bovine peptide-B from fibrinogen was capable of accelerating the structural and enzymatic effects associated with superprecipitation of myosin B. The rate of superprecipitation coupled with the hydrolysis of ATP are increased during the structural transformation. In the concentration range from 10-8 to 10-4 M peptide-B, the rate of superprecipitation is increased 12-fold while the hydrolysis of ATP doubles and the time to reach the final extent of superprecipitation is decreased 68%. Under these same conditions, the hydrolysis of ATP by myosin A was unaffected. The concentrations of magnesium and calcium were between 10 and 20 muM, and no additional divalent metal ions were added to the system. Superprecipitation was treated as a model for muscle contraction to explain the in vivo studies of bovine peptide-B in which the peptide behaves as a vasopressor substance producing vascular vasoconstriction. A possible mechanism for the participation of bovine peptide-B in the model for muscle contraction, based on the polarizing interaction of the highly charged density of negativity of the peptide with the actomyosin complex, is presented. Furthermore, bovine peptide-B is speculated as participating in vasoconstriction via attachment to some smooth muscle receptor.
来自纤维蛋白原的牛肽B能够加速与肌球蛋白B超沉淀相关的结构和酶促效应。在结构转变过程中，超沉淀速率与ATP水解速率一同增加。在10⁻⁸至10⁻⁴M肽B的浓度范围内，超沉淀速率增加了12倍，而ATP水解速率翻倍，达到超沉淀最终程度的时间减少了68%。在相同条件下，肌球蛋白A对ATP的水解不受影响。镁和钙的浓度在10至20μM之间，且未向系统中添加额外的二价金属离子。超沉淀被视为肌肉收缩的模型，以解释牛肽B的体内研究，其中该肽表现为产生血管收缩的血管加压物质。基于该肽高电荷密度的负性与肌动球蛋白复合物的极化相互作用，提出了牛肽B参与肌肉收缩模型的一种可能机制。此外，推测牛肽B通过附着于某些平滑肌受体参与血管收缩。
