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用质谱学方法测定分子的氢氘交换反应过程和结果是研究蛋白质分子等生物体系的分子构象,如蛋白质折叠状态的常用方法之一.本文利用线型离子阱-飞行时间质谱技术,在气相中测定了由不同个数钠离子所取代的简单多肽分子——五联丙氨酸(5Ala-nH+nNa).H+,n=2,3,4,5的氢氘交换反应情况,得到了由不同个数钠离子取代的分子离子的氢氘交换反应速度以及交换的氢氘数量等,并研究了钠离子个数对分子氢氘交换反应的影响.结果表明,在本工作的实验条件下,钠离子的取代将影响分子离子的氢氘交换反应.当钠离子数为2时,(5Ala-2H+2Na).H+分子离子很难发生氢氘交换反应;当钠离子数增加时,对于(5Ala-3H+3Na).H+,(5Ala-4H+4Na).H+,和(5Ala-5H+5Na).H+等,分子的氢氘交换反应速度会加快.这可能是由于钠离子的取代导致了分子离子的构型以及分子的质子亲和势发生了显著的改变,因此影响它们的氢氘交换反应.此外,我们还研究了线型四极场的q值对离子氢氘交换反应的影响,发现对于某种离子,当其对应的四极场q值低于0.8时,对各种离子的交换反应速度影响不大,但当q值接近第一稳定区图的边界点,即当q接近0.908时,对某些离子的交换反应速度影响很明显.q值对离子的交换反应速度影响可以用离子的运动速度加快而导致碰撞反应能量增加来解释.
It is one of the common methods to study the molecular conformation of biological systems such as protein molecules, such as the state of protein folding, using mass spectrometry to determine the hydrogen-deuterium exchange reaction process and result of the molecule.In this paper, linear ion trap-time of flight mass spectrometry (5Ala-nH + nNa) .H +, n = 2, 3, 4, 5 hydrogen deuterium exchange reaction was measured by different number of sodium ions, Hydrogen-deuterium exchange reaction speed of molecular ions substituted with different numbers of sodium ions and the amount of hydrogen-deuterium exchange were studied, and the influence of the number of sodium ions on the exchange reaction of hydrogen and hydrogen molecules was studied.The results showed that under the experimental conditions of this work, When the number of sodium ions is 2, the hydrogen-deuterium exchange reaction of (5Ala-2H + 2Na) .H + molecular ions is difficult to occur. When the number of sodium ions is increased, (5Ala-4H + 4Na) .H +, and (5Ala-5H + 5Na) .H +, etc., the hydrogen-deuterium exchange reaction of molecules will be accelerated, which may be due to the substitution of sodium ions The configuration of the molecular ions and the proton affinities of the molecules have undergone significant changes that affect it We also study the effect of the q value of the linear quadrupole field on the ion exchange reaction of hydrogen and deuterium and find that for some ions, when the q value of the corresponding quadrupole field is lower than 0.8, However, when the q value is close to the boundary of the first stable region graph, when q is close to 0.908, the effect on the exchange reaction speed of some ions is obvious. The effect of exchange reaction speed can be explained by the acceleration of ion movement resulting in an increase in collision reaction energy.