Army Health and Performance Research, Army Headquarters, Andover, United Kingdom.
Division of Surgery & Interventional Science, University College London, London, United Kingdom.
Adv Nutr. 2021 Jun 1;12(3):887-896. doi: 10.1093/advances/nmaa123.
Protein turnover reflects the continual synthesis and breakdown of body proteins, and can be measured at a whole-body (i.e. aggregated across all body proteins) or tissue (e.g. skeletal muscle only) level using stable isotope methods. Evaluating protein turnover in free-living environments, such as military training, can help inform protein requirements. We undertook a narrative review of published literature with the aim of reviewing the suitability of, and advancements in, stable isotope methods for measuring protein turnover in field research. The 2 primary approaches for measuring protein turnover are based on precursor- and end-product methods. The precursor method is the gold-standard for measuring acute (over several hours) skeletal muscle protein turnover, whereas the end-product method measures chronic (over several weeks) skeletal muscle protein turnover and provides the opportunity to monitor free-living activities. Both methods require invasive procedures such as the infusion of amino acid tracers and muscle biopsies to assess the uptake of the tracer into tissue. However, the end-product method can also be used to measure acute (over 9-24 h) whole-body protein turnover noninvasively by ingesting 15N-glycine, or equivalent isotope tracers, and collecting urine samples. The end-product method using 15N-glycine is a practical method for measuring whole-body protein turnover in the field over short (24 h) time frames and has been used effectively in recent military field research. Application of this method may improve our understanding of protein kinetics during conditions of high physiological stress in free-living environments such as military training.
蛋白质周转率反映了身体蛋白质的持续合成和分解，可以使用稳定同位素方法在全身（即跨越所有身体蛋白质）或组织（例如仅骨骼肌）水平上进行测量。在自由生活环境（例如军事训练）中评估蛋白质周转率可以帮助了解蛋白质需求。我们对已发表的文献进行了叙述性综述，旨在回顾稳定同位素方法在野外研究中测量蛋白质周转率的适用性和进展。测量蛋白质周转率的 2 种主要方法基于前体和终产物方法。前体方法是测量急性（数小时内）骨骼肌蛋白质周转率的金标准，而终产物方法测量慢性（数周内）骨骼肌蛋白质周转率，并提供监测自由生活活动的机会。这两种方法都需要侵入性程序，例如输注氨基酸示踪剂和肌肉活检，以评估示踪剂进入组织的情况。然而，终产物方法也可以通过摄入 15N-甘氨酸或等效的同位素示踪剂并收集尿液样本，非侵入性地测量急性（9-24 小时内）全身蛋白质周转率。使用 15N-甘氨酸的终产物方法是在短时间（24 小时）内测量野外全身蛋白质周转率的实用方法，并且在最近的军事野外研究中已有效应用。该方法的应用可能会增进我们对自由生活环境（例如军事训练）中高生理应激条件下蛋白质动力学的理解。
