It is found in research on protein through Neontology that there is an intermediate substance that consists of amino acid yet is different from protein.

• 现代生物学在研究蛋白质时发现，有一类由氨基酸构成，但又不同于蛋白质的中间物质，这类具有蛋白质特性的物质便是“活性肽”。