Krust B

References (4)

Title : Specific and irreversible cyclopeptide inhibitors of dipeptidyl peptidase IV activity of the T-cell activation antigen CD26 - Nguyen_1998_J.Med.Chem_41_2100
Author(s) : Nguyen C , Blanco J , Mazaleyrat JP , Krust B , Callebaut C , Jacotot E , Hovanessian AG , Wakselman M
Ref : Journal of Medicinal Chemistry , 41 :2100 , 1998
Abstract : The dipeptidyl peptidase IV (DPP IV) activity of CD26 is characterized by its post-proline-cleaving capacity that plays an important but not yet understood role in biological processes. Here we describe a new family of specific and irreversible inhibitors of this enzyme. Taking into account the substrate specificity of DPP IV for P2-P1><-P1' cleavage, we have designed and synthesized cyclopeptides c[(alphaH2N+)-Lys-Pro-Aba-(6-CH2-S+R2)-Glyn] 2TFA- (Aba = 3-aminobenzoic acid, R = alkyl) possessing a proline at the P1 position and a lysine in the P2 position, which allows the closing of the cycle on its side chain. These molecules show a free N-terminus, necessary for binding to the CD26 catalytic site, and a latent quinoniminium methide electrophile, responsible for inactivation. Treatment of c[alphaZ-Lys-Pro-Aba-(6-CH2-OC6H5)-Glyn], obtained by peptide synthesis in solution, with R2S/TFA simutaneously cleaved the Z protecting group and the phenyl ether function and led to a series of cyclopeptide sulfonium salts. These cyclopeptides inhibited rapidly and irreversibly the DPP IV activity of CD26, with IC50 values in the nanomolar range. Further studies were carried out to investigate the effect of the modification of the ring size (n = 2 or 4) and the nature of the sulfur substituents (R = Me, Bu, Oct). Cycle enlargement improved the inhibitory activity of the methylsulfonio cyclopeptide, whereas the increase of the alkyl chain length on the sulfur atom had no apparent effect. Other aminopeptidases were not inhibited, and a much weaker activity was observed on a novel isoform of DPP IV referred to as DPP IV-beta. Thus, this new family of irreversible inhibitors of DPP IV is highly specific to the peptidase activity of CD26.
ESTHER : Nguyen_1998_J.Med.Chem_41_2100
PubMedSearch : Nguyen_1998_J.Med.Chem_41_2100
PubMedID: 9622551

Title : Dipeptidyl-peptidase IV-beta--further characterization and comparison to dipeptidyl-peptidase IV activity of CD26 - Blanco_1998_Eur.J.Biochem_256_369
Author(s) : Blanco J , Nguyen C , Callebaut C , Jacotot E , Krust B , Mazaleyrat JP , Wakselman M , Hovanessian AG
Ref : European Journal of Biochemistry , 256 :369 , 1998
Abstract : Dipeptidyl peptidase IV-beta (DPP IV-beta) is a novel protein which shows a peptidase activity similar to the T-cell-activation antigen CD26. To further characterize this DPP IV-beta and confirm its cell surface expression, we have developed a purification strategy using the CD26- cell line C8166. The purification process includes biotinylation of cell surface proteins before preparation of cell extracts and processing by gel-filtration, ion-exchange and lectin chromatographies. Consistent with the molecular mass of DPP IV-beta estimated by gel-filtration chromatography, the final purified fraction, manifesting a typical DPP IV activity, showed a major biotinylated 75-80-kDa band in SDS/PAGE, thus suggesting the monomeric nature of this enzyme. Kinetic parameters of DPP IV-beta and the sensitivity to a new family of irreversible DPP IV inhibitors, were studied in comparison to CD26. Both enzymes followed a Michaelis kinetics with different Km values for Gly-Pro-NH-Np (NH-Np, para-nitroanilide) hydrolysis (0.28+/-0.05 mM and 0.12+/-0.02 mM). More significant differences were observed in the sensitivity to inhibitors, which exerted a much higher activity on CD26 than on DPP IV-beta. These differences permitted us to study DPP IV-beta expression in CD26-expressing cells, showing the expression of this new enzyme in all lymphoid cells tested, and a rapid enhancement in phytohemagglutinin-stimulated or protein-A-stimulated peripheral blood mononuclear cells. Our results indicate that, although DPP IV-beta and CD26 are coexpressed and manifest a typical DPP IV activity, there are distinct features in their catalytic activities that may confer to each enzyme a complementary role in peptide processing.
ESTHER : Blanco_1998_Eur.J.Biochem_256_369
PubMedSearch : Blanco_1998_Eur.J.Biochem_256_369
PubMedID: 9760177

Title : Dipeptidyl-peptidase IV-beta, a novel form of cell-surface-expressed protein with dipeptidyl-peptidase IV activity - Jacotot_1996_Eur.J.Biochem_239_248
Author(s) : Jacotot E , Callebaut C , Blanco J , Krust B , Neubert K , Barth A , Hovanessian AG
Ref : European Journal of Biochemistry , 239 :248 , 1996
Abstract : The T-cell activation antigen CD26, is a type II membrane glycoprotein with intrinsic dipeptidyl-peptidase IV (DPP IV) activity, characterized by its capacity to cleave off N-terminal dipeptides containing proline as the penultimate residue. Independent of its catalytic activity, CD26 has also been characterized as adenosine deaminase binding protein. By using CD26 negative human C8166 cells, here we describe the existence of another cell-surface protein which manifests CD26-like DPP IV activity. For convenience, this protein will be referred to as DPP IV-beta. Consistent with the cell-surface expression of DPP IV-beta, intact C8166 cells manifested a high level of DPP IV, whereas, they manifested poor activity against substrates of DPP II known to have an intracellular localization. A partially purified preparation of CD26 from human MOLT4 cells, and the DPP IV-beta expressed on intact cells were found to possess similar catalytic activity and pH optimum. In addition, cell-surface CD26 and DPP IV-beta on intact MOLT4 and C8166 cells, respectively, resisted digestion by proteolytic enzymes such as trypsin and proteinase K. However, adenosine deaminase activity was not detectable on the surface of C8166 cells in contrast to CD26 positive MOLT4 cells. In accord with this, 125I-labeled adenosine deaminase which binds CD26 was found not to bind DPP IV-beta. Gel-filtration experiments using 0.5% Triton X-100 extracts from C8166 and MOLT4 cells, revealed that the apparent molecular mass of DPP IV-beta is 82 kDa, whereas that of CD26 is 110 kDa as expected. Taken together, our results suggest that DPP IV-beta is a CD26-like protein which could be characterized by distinct properties.
ESTHER : Jacotot_1996_Eur.J.Biochem_239_248
PubMedSearch : Jacotot_1996_Eur.J.Biochem_239_248
PubMedID: 8706727

Title : T cell activation antigen, CD26, as a cofactor for entry of HIV in CD4+ cells - Callebaut_1993_Science_262_2045
Author(s) : Callebaut C , Krust B , Jacotot E , Hovanessian AG
Ref : Science , 262 :2045 , 1993
Abstract : The CD4 molecule is essential for binding HIV particles, but is not sufficient for efficient viral entry and infection. The cofactor was shown to be dipeptidyl peptidase IV (DPP IV), also known as CD26. This serine protease cleaves its substrates at specific motifs; such motifs area also highly conserved in the V3 loops of HIV-1, HIV-2, and related simian isolates. Entry of HIV-1 or HIV-2 into T lymphoblastoid and monocytoid cell lines was inhibited by a specific monoclonal antibody against DPP IV or specific peptide inhibitors of this protease. Coexpression of human CD4 and CD26 in murine NIH 3T3 cells rendered them permissive to infection by HIV-1 and HIV-2. These observations could provide the basis for developing simple and specific inhibitors of HIV and open a possibility for vaccine development.
ESTHER : Callebaut_1993_Science_262_2045
PubMedSearch : Callebaut_1993_Science_262_2045
PubMedID: 7903479