biostudies-literatureDeetanya PAgricultural Research Development Agency (ARDA) of ThailandScience Achievement Scholarship of ThailandChulalongkorn UniversityMichigan Economic Development Corporation and the Michigan Technology Tri-CorridorNational Research Council of ThailandDevelopment and Promotion of Science and Technology Talents Project (DPST)Agricultural Research Development AgencyDOE Office of Science by Argonne National LaboratoryThailand Toray Science Foundation90th Anniversary of Chulalongkorn University Scholarshipe5230https://www.ebi.ac.uk/biostudies/studies/S-EPMC11577449biostudies-literatureUnknown33(12)Kunitz-type trypsin inhibitors are ubiquitous in plants. They have been proposed to be a part of a defense mechanism against herbivores. Trypsin inhibitors also have potential applications in the biotechnology industry, such as in mammalian cell culture. We discovered that durian (Durio zibethinus) seed contains Kunitz-type trypsin inhibitors as identified by N-terminal sequencing and mass spectrometry. Eleven new trypsin inhibitors were cloned. The D. zibethinus trypsin inhibitors (DzTIs) that are likely expressed in the seed were produced as recombinant proteins and tested for trypsin inhibitory activity. Their inhibitory activity and crystal structures are similar to the soybean trypsin inhibitor. Surprisingly, a crystal structure of the complex between DzTI-4, the DzTI with the lowest Protein science : a publication of the Protein SocietyKunitz-type trypsin inhibitor from durian (Durio zibethinus) employs a distinct loop for trypsin inhibition.PMC11577449PRP6305030220N42A650270DE-AC02-06CH11357GCUGR1125652027DRES_65_389_23_0392021085P1000817CU_GR_62_28_23_10Sabat GLimsardsanakij KWangkanont KPattaradilokrat SDeetanya PChaisuekul CfalseKunitz-type trypsin inhibitor from durian (Durio zibethinus) employs a distinct loop for trypsin inhibition.Kunitz-type trypsin inhibitors are ubiquitous in plants. They have been proposed to be a part of a defense mechanism against herbivores. Trypsin inhibitors also have potential applications in the biotechnology industry, such as in mammalian cell culture. We discovered that durian (Durio zibethinus) seed contains Kunitz-type trypsin inhibitors as identified by N-terminal sequencing and mass spectrometry. Eleven new trypsin inhibitors were cloned. The D. zibethinus trypsin inhibitors (DzTIs) that are likely expressed in the seed were produced as recombinant proteins and tested for trypsin inhibitory activity. Their inhibitory activity and crystal structures are similar to the soybean trypsin inhibitor. Surprisingly, a crystal structure of the complex between DzTI-4, the DzTI with the lowest 2024-01-01T00:00:00Z2024 Dec2026-06-11T03:11:45.065Z2026-06-11T03:08:03.438ZS-EPMC115774493956506810.1002/pro.5230