Synthesis of methods used to assess soil protease activity

Proteases play a crucial role in the soil nitrogen (N) cycle by converting protein to oligopeptides and amino acids. They are often viewed as bottleneck terrestrial N cycling; therefore, it is vital that we have robust methods for evaluating protease activity understand global patterns of activity. In response this, several laboratory-based been developed subsequently modified. However, validity these different approaches remains largely unknown. addition, lack standardised protocols makes difficult compare across studies. this systematic synthesis, critically evaluate most common colorimetric fluorimetric used measure involving 680 independent studies 1,491 individual assays. To investigate key regulators activity, collected associated metadata on environmental (mean annual temperature pH) methodological (assay factors. Protease measured with substrates were centred around ca. 1000 nmol product g?1 h?1, whilst rates lower at 100 h?1. Fluorimetric target proteases which likely abundances, kinetic parameters, catalytic mechanism or ecological function suggesting why higher We found varied widely peaks, due wide range factors may influence/bias result. present following recommendations measuring activity: 1) report assay conditions characteristics, particularly pH temperature, 2) conduct either field optimised conditions, and, 3) check measurements lie between 0 5000 This will help reduce variation bias improve reporting abiotic biotic data. Altogether lead better understanding drivers refine parameterisation biogeochemical models.