Biological macromolecules are found in different shapes and sizes. Among these, enzymes catalyze biochemical reactions and are essential in all organisms, but is there a limit size for them to function properly? Large enzymes such as catalases have hundreds of kDa and are formed by multiple subunits, whereas most enzymes are smaller, with molecular weights of 20–60 kDa. Enzymes smaller than 10 kDa could be called microenzymes and the present literature review brings together evidence of their occurrence in nature. Additionally, bioactive peptides could be a natural source for novel microenzymes hidden in larger peptides and molecular downsizing could be useful to engineer artificial enzymes with low molecular weight improving their stability and heterologous expression. An integrative approach is crucial to discover and determine the amino acid sequences of novel microenzymes, together with their genomic identification and their biochemical biological and evolutionary functions.

生物大分子具有不同的形状和大小。其中，酶催化生化反应，是所有生物体所必需的，但它们正常发挥功能是否有大小限制呢？过氧化氢酶等大型酶有数百 kDa，由多个亚基形成，而大多数酶较小，分子量为 20-60 kDa。小于 10 kDa 的酶可称为微酶，目前的文献综述汇集了它们在自然界中存在的证据。此外，生物活性肽可能是隐藏在较大肽中的新型微酶的天然来源，并且分子尺寸缩小可用于设计低分子量的人工酶，从而提高其稳定性和异源表达。综合方法对于发现和确定新型微酶的氨基酸序列及其基因组鉴定及其生化生物学和进化功能至关重要。