The missing hydrogen ion, part-1: Historical precedents vs. fundamental concepts

IF 2.3 Q2 SPORT SCIENCES
Robert Robergs , Bridgette O'Malley , Sam Torrens , Jason Siegler
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引用次数: 0

Abstract

The purpose of this review and commentary was to provide an historical and evidence-based account of organic acids and the biochemical and organic chemistry evidence for why cells do not produce metabolites that are acids. The scientific study of acids has a long history dating to the 16th and 17th centuries, and the definition of an acid was proposed in 1884 as a molecule that when in an aqueous solution releases a hydrogen ion (H+). There are three common ionizable functional groups for molecules classified as acids: 1) the carboxyl group, 2) the phosphoryl group and 3) the amine group. The propensity by which a cation will associate or dissociate with a negatively charged atom is quantified by the equilibrium constant (Keq) of the dissociation constant (Kd) of the ionization (Keq ​= ​Kd), which for lactic acid (HLa) vs. lactate (La-) is expressed as: Keq=Kd=[H+][La][HLa]= 4 677.351 4 (ionic strength ​= ​0.01 Mol⋅L-1, T ​= ​25 ​°C). The negative log10 of the dissociation pKd reveals the pH at which half of the molecules are ionized, which for HLa ​= ​3.67. Thus, knowing the pKd and the pH of the solution at question will reveal the extent of the ionization vs. acidification of molecules that are classified as acids.

缺失的氢离子,第一部分:历史先例与基本概念
本综述和评论的目的是对有机酸以及细胞不产生酸性代谢物的生化和有机化学证据进行历史和循证阐述。对酸的科学研究由来已久,可追溯到 16 和 17 世纪,1884 年提出的酸的定义是在水溶液中释放出氢离子(H+)的分子。归类为酸的分子有三种常见的可电离官能团:1)羧基;2)磷酸基;3)胺基。阳离子与带负电荷的原子结合或解离的倾向是通过电离解离常数(Kd)的平衡常数(Keq)来量化的(Keq = Kd),对于乳酸(HLa)与乳酸盐(La-),平衡常数(Keq)表示为Keq=Kd=[H+][La-][HLa]=4 677.351 4(离子强度=0.01 摩尔-升-1,温度=25 °C)。解离 pKd 的负 log10 显示了一半分子电离时的 pH 值,HLa=3.67。因此,了解了 pKd 和相关溶液的 pH 值,就可以知道被归类为酸的分子的电离与酸化程度。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Sports Medicine and Health Science
Sports Medicine and Health Science Health Professions-Physical Therapy, Sports Therapy and Rehabilitation
CiteScore
5.50
自引率
0.00%
发文量
36
审稿时长
55 days
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