▎ 摘　　要

NOVELTY - A polypeptide for capturing terpene and/or ecgonine derivative, is new. The polypeptide comprises a peptide bound comprising a first amino acid having an aromatic side chain, a second amino acid having a hydrophobic side chain, a third amino acid having a hydrophobic side chain, a fourth amino acid having a hydrophobic side chain and a fifth amino acid having an aromatic side chain, where the second to fourth amino acids of the peptide do not contain an aromatic group or a guanidino group in their side chains. USE - The polypeptide is useful in chemical sensor or system for detecting a target substance. The target substance is terpene, ecgonine derivative, and narcotic. The narcotic is at least one chosen from cocaine, crack, Cannabis and marijuana. The terpene is monocyclic monoterpene chosen from limonene, terpinolene and terpinene. The ecgonine derivative is at least one chosen from ecgonine methyl ester, anhydrous ecgonine methyl ester, benzoylecgonine, methyl benzoylecgonine and methyl benzoylecgonine hydrochloride (all claimed). ADVANTAGE - The polypeptide detects terpene and ecgonine derivative with high sensitivity. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: a chemical sensor comprising a sensor element in which the polypeptide is immobilized; and a system comprising a chemical sensor comprising an immobilized polypeptide, and an intake mechanism configured to bring an analyte atmosphere onto the chemical sensor.