However, the techniques can require large amounts (100–200 mg) of isotopically labeled proteins and are most informative when applied to small proteins where spectroscopic assignments are possible.
然而，该技术要求大量（100至200毫克）的用同位素标记过的蛋白质，而且，当应用于可进行光谱分析的小分子蛋白时，产生的信息将最为有效。