Various peptides with inhibitory activity against human dipeptidyl peptidase-IV (hDPP-IV), which degrades glucagon-like peptide 1 (GLP-1) and decreases insulin release, were isolated from synthetic tripeptide mixtures, having sequences Val-Pro-Xaa (VPX) or Ile-Pro-Xaa (IPX). All peptides isolated by reversed-phase high performance liquid chromatography (HPLC) analysis were measured for hDPP-IV inhibitory activity. VPV and VPI prepared from the VPX mixture and IPI isolated from the IPX mixture, showed the highest hDPP-IV inhibitory activity. The dissociation constants for hDPP-IV and IC₅₀ values of the peptides were analyzed to understand the reason for the potent inhibitory activity of these tripeptides. The IC₅₀ and Ki values of VPV, VPI, and IPI were found to be 20.2, 22.2, and 46.7 µM and 10.8, 11.3 and 21.4 M⁻¹, respectively. Further, degradation of the peptides by the proteolytic action of hDPP-IV was analyzed to understand the stability of these peptides. Peptides with lower Ki and IC₅₀ values showed relatively slower degradation when incubated with hDPP-IV. These results suggested that a peptide might have higher hDPP-IV inhibitory activity because of its higher affinity and stronger resistance to hDPP-IV, which is caused by the introduction of a hydrophobic amino acid at the C-terminal end of its VP or IP sequence.

从具有序列Val-Pro-Xaa（VPX）的合成三肽混合物中分离出具有多种抗人二肽基肽酶IV（hDPP-IV）抑制活性的肽，该肽可降解胰高血糖素样肽1（GLP-1）并降低胰岛素释放。 ）或Ile-Pro-Xaa（IPX）。测量了通过反相高效液相色谱（HPLC）分析分离的所有肽的hDPP-IV抑制活性。从VPX混合物制备的VPV和VPI和从IPX混合物分离的IPI显示出最高的hDPP-IV抑制活性。分析了肽的hDPP-IV的解离常数和IC ₅₀值，以了解这些三肽有效抑制活性的原因。IC ₅₀和Ki发现VPV，VPI和IPI的值分别为20.2、22.2和46.7 µM，以及10.8、11.3和21.4 M ^-1。此外，分析了通过hDPP-IV的蛋白水解作用降解肽以了解这些肽的稳定性。当与hDPP-IV孵育时，具有较低Ki和IC ₅₀值的肽显示相对较慢的降解。这些结果表明，一种肽可能具有更高的hDPP-IV抑制活性，因为它具有更高的亲和力和更强的对hDPP-IV的抵抗力，这是由于在其VP或IP序列的C端引入了疏水氨基酸造成的。 。