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Singhal S, Manikrao Patil V, Verma S, Masand N. Recent advances and structure-activity relationship studies of DPP-4 inhibitors as anti-diabetic agents. Bioorg Chem 2024; 146:107277. [PMID: 38493634 DOI: 10.1016/j.bioorg.2024.107277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 02/02/2024] [Accepted: 03/08/2024] [Indexed: 03/19/2024]
Abstract
Diabetes mellitus (DM) is one of the largest public health problems worldwide and in the last decades various therapeutic targets have been investigated. For the treatment of type-2 DM (T2DM), dipeptidyl peptidase-4 (DPP-4) is one of the well reported target and has established safety in terms of cardiovascular complexicity. Preclinical and clinical studies using DPP-4 inhibitors have demonstrated its safety and effectiveness and have lesser risk of associated hypoglycaemic effect making it suitable for elderly patients. FDA has approved a number of structurally diverse DPP-4 inhibitors for clinical use. The present manuscript aims to focus on the well reported hybrid and non-hybrid analogues and their structural activity relationship (SAR) studies. It aims to provide structural insights for this class of compounds pertaining to favourable applicability of selective DPP-4 inhibitors in the treatment of T2DM.
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Affiliation(s)
- Shipra Singhal
- Department of Pharmaceutical Chemistry, KIET School of Pharmacy, KIET Group of Institutions, Delhi NCR, Ghaziabad, Uttar Pradesh, India
| | - Vaishali Manikrao Patil
- Charak School of Pharmacy, Chaudhary Charan Singh (CCS) University, Meerut, Uttar Pradesh, India; Faculty of Pharmaceutical Sciences, UCSI University, Kuala Lumpur, Malaysia.
| | - Saroj Verma
- Department of Pharmacy, School of Medical and Allied Sciences, K. R. Mangalam University, Gurugram, India
| | - Neeraj Masand
- Department of Pharmacy, Lala Lajpat Rai Memorial Medical College, Meerut, Uttar Pradesh, India
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Cehofski LJ, Kojima K, Kusada N, Hansen MS, Muttuvelu DV, Bakker N, Klaassen I, Grauslund J, Vorum H, Honoré B. Central subfield thickness of diabetic macular edema: Correlation with the aqueous humor proteome. Mol Vis 2024; 30:17-35. [PMID: 38586604 PMCID: PMC10994682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Accepted: 02/07/2024] [Indexed: 04/09/2024] Open
Abstract
Purpose Diabetic macular edema (DME) is a sight-threatening complication of diabetes. Consequently, studying the proteome of DME may provide novel insights into underlying molecular mechanisms. Methods In this study, aqueous humor samples from eyes with treatment-naïve clinically significant DME (n = 13) and age-matched controls (n = 11) were compared with label-free liquid chromatography-tandem mass spectrometry. Additional aqueous humor samples from eyes with treatment-naïve DME (n = 15) and controls (n = 8) were obtained for validation by enzyme-linked immunosorbent assay (ELISA). Best-corrected visual acuity (BCVA) was evaluated, and the severity of DME was measured as central subfield thickness (CST) employing optical coherence tomography. Control samples were obtained before cataract surgery. Significantly changed proteins were identified using a permutation-based calculation, with a false discovery rate of 0.05. A human donor eye with DME and a control eye were used for immunofluorescence. Results A total of 101 proteins were differentially expressed in the DME. Regulated proteins were involved in complement activation, glycolysis, extracellular matrix interaction, and cholesterol metabolism. The highest-fold change was observed for the fibrinogen alpha chain (fold change = 17.8). Complement components C2, C5, and C8, fibronectin, and hepatocyte growth factor-like protein were increased in DME and correlated with best-corrected visual acuity (BCVA). Ceruloplasmin and complement component C8 correlated with central subfield thickness (CST). Hemopexin, plasma kallikrein, monocyte differentiation antigen CD14 (CD14), and lipopolysaccharide-binding protein (LBP) were upregulated in the DME. LBP was correlated with vascular endothelial growth factor. The increased level of LBP in DME was confirmed using ELISA. The proteins involved in desmosomal integrity, including desmocollin-1 and desmoglein-1, were downregulated in DME and correlated negatively with CST. Immunofluorescence confirmed the extravasation of fibrinogen at the retinal level in the DME. Conclusion Elevated levels of pro-inflammatory proteins, including the complement components LBP and CD14, were observed in DME. DME was associated with the loss of basal membrane proteins, compromised desmosomal integrity, and perturbation of glycolysis.
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Affiliation(s)
- Lasse Jørgensen Cehofski
- Department of Ophthalmology, Odense University Hospital, Odense, Denmark
- Department of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Kentaro Kojima
- Department of Ophthalmology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Natsuki Kusada
- Department of Ophthalmology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | | | - Danson Vasanthan Muttuvelu
- Department of Ophthalmology, Mitoje Aps, Skive, Denmark
- University of Copenhagen, Faculty of Health Sciences, Copenhagen, Denmark
| | - Noëlle Bakker
- Ocular Angiogenesis Group, Department of Ophthalmology, Amsterdam UMC location University of Amsterdam, Amsterdam, The Netherlands
| | - Ingeborg Klaassen
- Ocular Angiogenesis Group, Department of Ophthalmology, Amsterdam UMC location University of Amsterdam, Amsterdam, The Netherlands
| | - Jakob Grauslund
- Department of Ophthalmology, Odense University Hospital, Odense, Denmark
- Department of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Henrik Vorum
- Department of Ophthalmology, Aalborg University Hospital, Aalborg, Denmark
- Department of Clinical Medicine, Aalborg University, Aalborg, Denmark
| | - Bent Honoré
- Department of Clinical Medicine, Aalborg University, Aalborg, Denmark
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
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Chen H, Haddadi N, Zhu X, Hatoum D, Chen S, Nassif NT, Lin Y, McGowan EM. Expression Profile of Sphingosine Kinase 1 Isoforms in Human Cancer Tissues and Cells: Importance and Clinical Relevance of the Neglected 1b-Isoform. JOURNAL OF ONCOLOGY 2022; 2022:2250407. [PMID: 36532885 PMCID: PMC9750787 DOI: 10.1155/2022/2250407] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 11/12/2022] [Accepted: 11/17/2022] [Indexed: 09/28/2023]
Abstract
BACKGROUND Overexpression of sphingosine kinase 1 (SphK1) is casually associated with many types of cancer, and inhibitors of SphK1 sensitize tumors to chemotherapy. SphK1 is expressed as two major isoforms, SphK1a and SphK1b. To date, no information has been reported on the SphK1 isoform expression profile and its clinical relevance. OBJECTIVE The objective is to examine the expression profile of the SphK1a and SPhK1b isoforms in human cancer and noncancer tissues and cell lines and explore their clinical relevance. METHODS We used PCR to qualitatively examine the expression profile of these two isoforms in breast, liver, and prostate cancer tissues plus paired adjacent tissues and in 11 cancer and normal cell lines (breast, cervical, bone, prostate, colon, brain, mesothelioma tumor and benign, and human kidney cells). RESULTS We found that SphK1a was ubiquitously expressed in all cancer cells and tissues tested; in contrast, SphK1b was only expressed in selective cell types in breast, prostate, and lung cancer. CONCLUSIONS Our data suggest that SphK1a is important for generic SphK1/S1P functions, and SphK1b mediates specialized and/or unique pathways in a specific type of tissue and could be a biomarker for cancer. This discovery is important for future SphK1-related cancer research and may have clinical implications in drug development associated with SphK1-directed cancer treatment.
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Affiliation(s)
- Hongjie Chen
- Department of Traditional Chinese Medicine, Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Nahal Haddadi
- School of Life Sciences, University of Technology Sydney, Broadway, NSW, Australia
| | - Xiaofeng Zhu
- Department of Transplant Surgery, First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Diana Hatoum
- School of Life Sciences, University of Technology Sydney, Broadway, NSW, Australia
- Public Health and College of Arts and Sciences, Phoenicia University, Daoudiye, Lebanon
| | - Size Chen
- Central Laboratory, First Affiliated Hospital of Guangdong Pharmaceutical University, Guangzhou, China
- Guangdong Provincial Engineering Research Center for Esophageal Cancer Precision Therapy, Guangdong Pharmaceutical University, Guangzhou, China
| | - Najah T. Nassif
- School of Life Sciences, University of Technology Sydney, Broadway, NSW, Australia
| | - Yiguang Lin
- Department of Traditional Chinese Medicine, Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
- School of Life Sciences, University of Technology Sydney, Broadway, NSW, Australia
- Central Laboratory, First Affiliated Hospital of Guangdong Pharmaceutical University, Guangzhou, China
| | - Eileen M. McGowan
- School of Life Sciences, University of Technology Sydney, Broadway, NSW, Australia
- Central Laboratory, First Affiliated Hospital of Guangdong Pharmaceutical University, Guangzhou, China
- Guangdong Provincial Engineering Research Center for Esophageal Cancer Precision Therapy, Guangdong Pharmaceutical University, Guangzhou, China
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Dunaevsky YE, Tereshchenkova VF, Oppert B, Belozersky MA, Filippova IY, Elpidina EN. Human proline specific peptidases: A comprehensive analysis. Biochim Biophys Acta Gen Subj 2020; 1864:129636. [DOI: 10.1016/j.bbagen.2020.129636] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 05/05/2020] [Accepted: 05/14/2020] [Indexed: 02/07/2023]
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Early changes in the urine proteome in a diethyldithiocarbamate-induced chronic pancreatitis rat model. J Proteomics 2018; 186:8-14. [DOI: 10.1016/j.jprot.2018.07.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 07/17/2018] [Accepted: 07/18/2018] [Indexed: 02/07/2023]
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Wagner L, Klemann C, Stephan M, von Hörsten S. Unravelling the immunological roles of dipeptidyl peptidase 4 (DPP4) activity and/or structure homologue (DASH) proteins. Clin Exp Immunol 2016; 184:265-83. [PMID: 26671446 DOI: 10.1111/cei.12757] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 12/01/2015] [Accepted: 12/14/2015] [Indexed: 12/31/2022] Open
Abstract
Dipeptidyl peptidase (DPP) 4 (CD26, DPP4) is a multi-functional protein involved in T cell activation by co-stimulation via its association with adenosine deaminase (ADA), caveolin-1, CARMA-1, CD45, mannose-6-phosphate/insulin growth factor-II receptor (M6P/IGFII-R) and C-X-C motif receptor 4 (CXC-R4). The proline-specific dipeptidyl peptidase also modulates the bioactivity of several chemokines. However, a number of enzymes displaying either DPP4-like activities or representing structural homologues have been discovered in the past two decades and are referred to as DPP4 activity and/or structure homologue (DASH) proteins. Apart from DPP4, DASH proteins include fibroblast activation protein alpha (FAP), DPP8, DPP9, DPP4-like protein 1 (DPL1, DPP6, DPPX L, DPPX S), DPP4-like protein 2 (DPL2, DPP10) from the DPP4-gene family S9b and structurally unrelated enzyme DPP2, displaying DPP4-like activity. In contrast, DPP6 and DPP10 lack enzymatic DPP4-like activity. These DASH proteins play important roles in the immune system involving quiescence (DPP2), proliferation (DPP8/DPP9), antigen-presenting (DPP9), co-stimulation (DPP4), T cell activation (DPP4), signal transduction (DPP4, DPP8 and DPP9), differentiation (DPP4, DPP8) and tissue remodelling (DPP4, FAP). Thus, they are involved in many pathophysiological processes and have therefore been proposed for potential biomarkers or even drug targets in various cancers (DPP4 and FAP) and inflammatory diseases (DPP4, DPP8/DPP9). However, they also pose the challenge of drug selectivity concerning other DASH members for better efficacy and/or avoidance of unwanted side effects. Therefore, this review unravels the complex roles of DASH proteins in immunology.
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Affiliation(s)
- L Wagner
- Deutschsprachige Selbsthilfegruppe für Alkaptonurie (DSAKU) e.V, Stuttgart.,Department for Experimental Therapy, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - C Klemann
- Centre of Paediatric Surgery.,Centre for Paediatrics and Adolescent Medicine
| | - M Stephan
- Clinic for Psychosomatics and Psychotherapy, Hannover Medical School, Hannover
| | - S von Hörsten
- Department for Experimental Therapy, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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Khaket TP, Dhanda S, Jodha D, Singh J. Purification and biochemical characterization of dipeptidyl peptidase-II (DPP7) homologue from germinated Vigna radiata seeds. Bioorg Chem 2015; 63:132-41. [PMID: 26524724 DOI: 10.1016/j.bioorg.2015.10.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 10/06/2015] [Accepted: 10/12/2015] [Indexed: 11/25/2022]
Abstract
Dipeptidyl peptidases (DPPs) are potent exopeptidases, which possess central role in proteolysis. As compared to other members of DPP family, proline containing dipeptide hydrolysing activity of DPP-II (Dipeptidyl peptidase II) is unique as it hydrolyses imino group and plays a key role in protein metabolism. In present study, DPP-II was purified from germinated moong bean seeds using acid and ammonium sulphate precipitation followed by successive chromatographies on gel filtration (pH 7.4) and cation exchanger (pH 5.9). Native PAGE and in-situ gel assay confirmed the apparent homogeneity. Purified plant DPP-II is an oligomeric enzyme with molecular weight of 97.3kDa. Highest DPP-II activity was observed at pH 7.5 and 37°C, with stability in the range of neutral to alkaline pH. Substrate specificity showed consequent activity for proline containing dipeptide followed by Lys-Ala and other hydrophobic dipeptides, but none of the studied endopeptidase and monopeptidase substrate was hydrolysed. Catalytic characterization with modifier studies revealed the involvement of Ser and His residues in its catalytic mechanism. Its dipeptidyl peptidase activity for proline containing dipeptide supported its role in the bioactive peptide generation and food industry. Functional studies of DPP-II revealed the significant involvement of this glycoproteinous enzyme in protein mobilization during germination. Further studies on industrial applications exploring physiological role are in progress.
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Affiliation(s)
- Tejinder Pal Khaket
- Department of Biochemistry, Kurukshetra University, Kurukshetra, Haryana, India; Department of Biotechnology, Maharishi Markandeshwar University, Ambala, Haryana, India
| | - Suman Dhanda
- Department of Biochemistry, Kurukshetra University, Kurukshetra, Haryana, India
| | - Druksakshi Jodha
- Department of Biochemistry, Kurukshetra University, Kurukshetra, Haryana, India
| | - Jasbir Singh
- Department of Biochemistry, Kurukshetra University, Kurukshetra, Haryana, India.
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Abstract
The HLA-F adjacent transcript 10 (FAT10) is a member of the ubiquitin-like gene family that alters protein function/stability through covalent ligation. Although FAT10 is induced by inflammatory mediators and implicated in immunity, the physiological functions of FAT10 are poorly defined. We report the discovery that FAT10 regulates lifespan through pleiotropic actions on metabolism and inflammation. Median and overall lifespan are increased 20% in FAT10ko mice, coincident with elevated metabolic rate, preferential use of fat as fuel, and dramatically reduced adiposity. This phenotype is associated with metabolic reprogramming of skeletal muscle (i.e., increased AMP kinase activity, β-oxidation and -uncoupling, and decreased triglyceride content). Moreover, knockout mice have reduced circulating glucose and insulin levels and enhanced insulin sensitivity in metabolic tissues, consistent with elevated IL-10 in skeletal muscle and serum. These observations suggest novel roles of FAT10 in immune metabolic regulation that impact aging and chronic disease.
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Structures of human DPP7 reveal the molecular basis of specific inhibition and the architectural diversity of proline-specific peptidases. PLoS One 2012; 7:e43019. [PMID: 22952628 PMCID: PMC3430648 DOI: 10.1371/journal.pone.0043019] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Accepted: 07/17/2012] [Indexed: 11/19/2022] Open
Abstract
Proline-specific dipeptidyl peptidases (DPPs) are emerging targets for drug development. DPP4 inhibitors are approved in many countries, and other dipeptidyl peptidases are often referred to as DPP4 activity- and/or structure-homologues (DASH). Members of the DASH family have overlapping substrate specificities, and, even though they share low sequence identity, therapeutic or clinical cross-reactivity is a concern. Here, we report the structure of human DPP7 and its complex with a selective inhibitor Dab-Pip (L-2,4-diaminobutyryl-piperidinamide) and compare it with that of DPP4. Both enzymes share a common catalytic domain (α/β-hydrolase). The catalytic pocket is located in the interior of DPP7, deep inside the cleft between the two domains. Substrates might access the active site via a narrow tunnel. The DPP7 catalytic triad is completely conserved and comprises Ser162, Asp418 and His443 (corresponding to Ser630, Asp708 and His740 in DPP4), while other residues lining the catalytic pockets differ considerably. The “specificity domains” are structurally also completely different exhibiting a β-propeller fold in DPP4 compared to a rare, completely helical fold in DPP7. Comparing the structures of DPP7 and DPP4 allows the design of specific inhibitors and thus the development of less cross-reactive drugs. Furthermore, the reported DPP7 structures shed some light onto the evolutionary relationship of prolyl-specific peptidases through the analysis of the architectural organization of their domains.
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Long JZ, Cravatt BF. The metabolic serine hydrolases and their functions in mammalian physiology and disease. Chem Rev 2011; 111:6022-63. [PMID: 21696217 DOI: 10.1021/cr200075y] [Citation(s) in RCA: 295] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Jonathan Z Long
- The Skaggs Institute for Chemical Biology and Department of Chemical Physiology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
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Alponti RF, Frezzatti R, Barone JM, Alegre VDS, Silveira PF. Dipeptidyl peptidase IV in the hypothalamus and hippocampus of monosodium glutamate obese and food-deprived rats. Metabolism 2011; 60:234-42. [PMID: 20153005 DOI: 10.1016/j.metabol.2009.12.031] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2009] [Revised: 12/30/2009] [Accepted: 12/31/2009] [Indexed: 12/17/2022]
Abstract
Proline-specific dipeptidyl peptidases are emerging as a protease family with important roles in the regulation of signaling by peptide hormones related to energy balance. The treatment of neonatal rats with monosodium glutamate (MSG) is known to produce a selective damage on the arcuate nucleus with development of obesity. This study investigates the relationship among dipeptidyl peptidase IV (DPPIV) hydrolyzing activity, CD26 protein, fasting, and MSG model of obesity in 2 areas of the central nervous system. Dipeptidyl peptidase IV and CD26 were, respectively, evaluated by fluorometry, and enzyme-linked immunosorbent assay and reverse transcriptase polymerase chain reaction in soluble (SF) and membrane-bound (MF) fractions from the hypothalamus and hippocampus of MSG-treated and normal rats, submitted or not to food deprivation (FD). Dipeptidyl peptidase IV in both areas was distinguished kinetically as insensitive (DI) and sensitive (DS) to diprotin A. Compared with the controls, MSG and/or FD decreased the activity of DPPIV-DI in the SF and MF from the hypothalamus, as well as the activity of DPPIV-DS in the SF from the hypothalamus and in the MF from the hippocampus. Monosodium glutamate and/or FD increased the activity of DPPIV-DI in the MF from the hippocampus. The monoclonal protein expression of membrane CD26 by enzyme-linked immunosorbent assay decreased in the hypothalamus and increased in the hippocampus of MSG and/or FD relative to the controls. The existence of DPPIV-like activity with different sensitivities to diprotin A and the identity of insensitive with CD26 were demonstrated for the first time in the central nervous system. Data also demonstrated the involvement of DPPIV-DI/CD26 hydrolyzing activity in the energy balance probably through the regulation of neuropeptide Y and β-endorphin levels in the hypothalamus and hippocampus.
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Affiliation(s)
- Rafaela Fadoni Alponti
- Laboratory of Pharmacology, Instituto Butantan, Av. Vital Brasil, 1500, 05503-900 São Paulo, SP, Brazil
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Kozarich JW. S28 peptidases: lessons from a seemingly 'dysfunctional' family of two. BMC Biol 2010; 8:87. [PMID: 20598110 PMCID: PMC2893137 DOI: 10.1186/1741-7007-8-87] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Accepted: 06/21/2010] [Indexed: 11/29/2022] Open
Abstract
Abstract A recent paper in BMC Structural Biology reports the crystal structure of human prolylcarboxypeptidase (PRCP), one of the two members of the S28 peptidase family. Comparison of the substrate-binding site of PRCP with that of its family partner, dipeptidyl dipeptidase 7 (DPP7), helps to explain the different enzymatic activities of these structurally similar proteins, and also reveals a novel apparent charge-relay system in PRCP involving the active-site catalytic histidine. See research article: http://www.biomedcentral.com/1472-6807/10/16/ Commentary The S28 serine peptidase family is something of an enzymatic odd couple. While showing low sequence similarity to all proteins except each other, the two known family members appear to be at odds functionally; one, prolylcarboxypeptidase (PRCP), is a carboxypeptidase that cleaves single hydrophobic residues from the carboxyl termini of proteins that end with a Pro-X motif (where X is any hydrophobic amino acid), while the other, human dipeptidyl peptidase (DPP7), is an aminopeptidase that cleaves amino-terminal X-Pro dipeptides. The structural basis of this orthogonal specificity would undoubtedly be interesting, and a recent report in BMC Structural Biology from the Merck Global Structural Biology group (Soisson et al. [1]) has now met that expectation. In addition they reveal a new wrinkle to the iconic catalytic triad common to most serine hydrolases. The practical pharmaceutical interest in both these enzymes as potential drug targets is at present speculative. PRCP can inactivate a number of peptide hormones, such as angiotensin II, III and prekallikrein, implicating a role for the enzyme in hypertension, tissue proliferation and smooth-muscle growth. These properties suggest that this enzyme may well be a useful target for hypertension and anti-inflammatory therapy [2]. Another (non-S28 family) dipeptidyl dipeptidase (DPP4) is a major drug target in type 2 diabetes, and Merck has already developed a successful inhibitor of DPP4, the anti-hyperglycemic drug sitagliptin, for the treatment of type 2 diabetes. The DPP enzymes are rich in biological functions and other drug targets emerging from the group are possible [3].
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