1. Protein quantification is a routine procedure in ecological studies despite the inherent limitations of well-acknowledged protein determination methods which have been largely overlooked by ecologists. Thus, we want to bridge this knowledge gap, in hopes of improving the way ecologists quantify proteins and interpret findings.
2. We surveyed the ecological literature to determine how and why ecologists quantify proteins. To determine whether different quantification methods produce comparable results across taxa, and between populations of a single species, we estimated the protein content of eight phylogenetically diverse taxa, and of desert isopods fed different diets, using various derived protocols of the 'crude protein', Bradford and bicinchoninic acid approach (BCA) methods.
3. We found that ecologists use many protein quantification procedures, often without reporting the crucial information needed to evaluate and repeat their methods. Our empirical work demonstrated that the three quantification methods examined, and their derived protocols, resulted in highly divergent protein estimations that were inconsistent in rank across taxa, preventing conversion between methods. We also found that different quantification methods yielded different answers to whether isopod protein content is affected by diet.
4. We conclude that commonly used quantification techniques yield distinct protein estimations with varying precision, and no single method is likely to be more accurate than another across taxa which may lead to inconsistent results across taxa and between conspecifics. Inaccurate protein quantification may explain the observed mismatch between organismal N and protein that has plagued some recent studies and that contradicts the principles of ecological stoichiometry. We recommend using a single BCA protocol to reduce inconsistencies across studies, until the promising amino acid analysis becomes more affordable, accurate and accessible to ecologists. Until then, ecologists should consider the abovementioned drawbacks of protein quantification methods and interpret their results accordingly.

中文翻译：

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生态研究中的蛋白质定量：标准方法的文献综述和实证比较

1. 尽管公认的蛋白质测定方法存在固有的局限性，但在很大程度上被生态学家忽视，蛋白质定量是生态研究中的常规程序。因此，我们希望弥合这一知识鸿沟，希望能改进生态学家量化蛋白质和解释发现的方式。
2. 我们调查了生态学文献，以确定生态学家如何以及为何量化蛋白质。为了确定不同的量化方法是否在整个分类群和单个物种的种群之间产生可比较的结果，我们估计了八个系统发育不同的分类群的蛋白质含量，以及喂食不同饮食的沙漠等足类动物，使用“粗蛋白质”的各种衍生协议， Bradford 和二辛可宁酸方法 (BCA) 方法。
3. 我们发现生态学家使用许多蛋白质定量程序，通常没有报告评估和重复他们的方法所需的关键信息。我们的实证工作表明，所检查的三种量化方法及其派生的协议导致了高度不同的蛋白质估计，这些估计在整个分类群中的等级不一致，从而阻止了方法之间的转换。我们还发现，对于等足动物蛋白含量是否受饮食影响，不同的量化方法产生了不同的答案。
4. 我们得出的结论是，常用的量化技术以不同的精度产生不同的蛋白质估计，并且没有一种方法可能比跨分类群的另一种方法更准确，这可能导致跨分类群和同种之间的结果不一致。不准确的蛋白质定量可以解释观察到的有机氮和蛋白质之间的不匹配，这种不匹配一直困扰着最近的一些研究，并且与生态化学计量学的原则相矛盾。我们建议使用单一的 BCA 协议来减少研究之间的不一致，直到有希望的氨基酸分析变得更加经济、准确和生态学家可以使用。在此之前，生态学家应该考虑蛋白质定量方法的上述缺点并相应地解释其结果。