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Jang L, Kim A, Park CS, Moon C, Kim M, Kim J, Yang S, Jang JY, Jeong CM, Lee HS, Park J, Kim K, Byeon H, Kim HH. Fucosylation and galactosylation in N-glycans of bovine intestinal alkaline phosphatase and their role in its enzymatic activity. Arch Biochem Biophys 2024; 758:110069. [PMID: 38914216 DOI: 10.1016/j.abb.2024.110069] [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: 01/03/2024] [Revised: 06/20/2024] [Accepted: 06/20/2024] [Indexed: 06/26/2024]
Abstract
Bovine intestinal alkaline phosphatase (biALP), a membrane-bound plasma metalloenzyme, maintains intestinal homeostasis, regulates duodenal surface pH, and protects against infections caused by pathogenic bacteria. The N-glycans of biALP regulate its enzymatic activity, protein folding, and thermostability, but their structures are not fully reported. In this study, the structures and quantities of the N-glycans of biALP were analyzed by liquid chromatography-electrospray ionization-high energy collision dissociation-tandem mass spectrometry. In total, 48 N-glycans were identified and quantified, comprising high-mannose [6 N-glycans, 33.1 % (sum of relative quantities of each N-glycan)], hybrid (6, 11.9 %), and complex (36, 55.0 %) structures [bi- (13, 26.1 %), tri- (16, 21.5 %), and tetra-antennary (7, 7.4 %)]. These included bisecting N-acetylglucosamine (33, 56.6 %), mono-to tri-fucosylation (32, 53.3 %), mono-to tri-α-galactosylation (16, 20.7 %), and mono-to tetra-β-galactosylation (36, 58.5 %). No sialylation was identified. N-glycans with non-bisecting GlcNAc (9, 10.3 %), non-fucosylation (10, 13.6 %), non-α-galactosylation (26, 46.2 %), and non-β-galactosylation (6, 8.4 %) were also identified. The activity (100 %) of biALP was reduced to 37.3 ± 0.2 % (by de-fucosylation), 32.7 ± 2.9 % (by de-α-galactosylation), and 0.2 ± 0.2 % (by de-β-galactosylation), comparable to inhibition by 10-4 to 101 mM EDTA, a biALP inhibitor. These results indicate that fucosylated and galactosylated N-glycans, especially β-galactosylation, affected the activity of biALP. This study is the first to identify 48 diverse N-glycan structures and quantities of bovine as well as human intestinal ALP and to demonstrate the importance of the role of fucosylation and galactosylation for maintaining the activity of biALP.
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Affiliation(s)
- Leeseul Jang
- Department of Global Innovative Drugs, Graduate School of Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Ahyeon Kim
- Department of Global Innovative Drugs, Graduate School of Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Chi Soo Park
- Department of Global Innovative Drugs, Graduate School of Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Chulmin Moon
- Department of Global Innovative Drugs, Graduate School of Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Mirae Kim
- Department of Global Innovative Drugs, Graduate School of Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Jieun Kim
- Department of Global Innovative Drugs, Graduate School of Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Subin Yang
- Department of Global Innovative Drugs, Graduate School of Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Ji Yeon Jang
- Department of Global Innovative Drugs, Graduate School of Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Chang Myeong Jeong
- Department of Global Innovative Drugs, Graduate School of Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Han Seul Lee
- Department of Global Innovative Drugs, Graduate School of Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Juhee Park
- Department of Pharmaceutical Regulatory Sciences, Graduate School of Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Kyuran Kim
- Department of Global Innovative Drugs, Graduate School of Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Haeun Byeon
- Department of Global Innovative Drugs, Graduate School of Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea
| | - Ha Hyung Kim
- Department of Global Innovative Drugs, Graduate School of Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea; Department of Pharmaceutical Regulatory Sciences, Graduate School of Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul, 06974, Republic of Korea.
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Gamov G, Murekhina A, Aleksandriiskii V. Dephosphorylation of pyridoxal 5′‐phosphate‐derived Schiff bases in the presence of bovine alkaline phosphatase. INT J CHEM KINET 2021. [DOI: 10.1002/kin.21541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- George Gamov
- Research Institute of Thermodynamics and Kinetics of Chemical Processes Ivanovo State University of Chemistry and Technology Ivanovo Russia
| | - Anastasia Murekhina
- Research Institute of Thermodynamics and Kinetics of Chemical Processes Ivanovo State University of Chemistry and Technology Ivanovo Russia
| | - Viktor Aleksandriiskii
- Research Institute of Thermodynamics and Kinetics of Chemical Processes Ivanovo State University of Chemistry and Technology Ivanovo Russia
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Katsipis G, Tsalouxidou V, Halevas E, Geromichalou E, Geromichalos G, Pantazaki AA. In vitro and in silico evaluation of the inhibitory effect of a curcumin-based oxovanadium (IV) complex on alkaline phosphatase activity and bacterial biofilm formation. Appl Microbiol Biotechnol 2020; 105:147-168. [PMID: 33191462 DOI: 10.1007/s00253-020-11004-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 10/27/2020] [Accepted: 11/03/2020] [Indexed: 12/18/2022]
Abstract
The scientific interest in the development of novel metal-based compounds as inhibitors of bacterial biofilm-related infections and alkaline phosphatase (ALP) deregulating effects is continuous and rising. In the current study, a novel crystallographically defined heteroleptic V(IV)-curcumin-bipyridine (V-Cur) complex with proven bio-activity was studied as a potential inhibitor of ALP activity and bacterial biofilm. The inhibitory effect of V-Cur was evaluated on bovine ALP, with two different substrates: para-nitrophenyl phosphate (pNPP) and adenosine triphosphate (ATP). The obtained results suggested that V-Cur inhibited the ALP activity in a dose-dependent manner (IC50 = 26.91 ± 1.61 μM for ATP, IC50 = 2.42 ± 0.12 μM for pNPP) exhibiting a mixed/competitive type of inhibition with both substrates tested. The evaluation of the potential V-Cur inhibitory effect on bacterial biofilm formation was performed on Gram (+) bacteria Staphylococcus aureus (S. aureus) and Gram (-) Escherichia coli (E. coli) cultures, and it positively correlated with inhibition of bacterial ALP activity. In silico study proved the binding of V-Cur at eukaryotic and bacterial ALP, and its interaction with crucial amino acids of the active sites, verifying complex's inhibitory potential. The findings suggested a specific anti-biofilm activity of V-Cur, offering a further dimension in the importance of metal complexes, with naturally derived products as biological ligands, as therapeutic agents against bacterial infections and ALP-associated diseases. KEY POINTS: • V-Cur inhibits bovine and bacterial alkaline phosphatases and bacterial biofilm formation. • Alkaline phosphatase activity correlates with biofilm formation. • In silico studies prove binding of the complex on alkaline phosphatase.
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Affiliation(s)
- G Katsipis
- Laboratory of Biochemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124, Thessaloniki, Greece
| | - V Tsalouxidou
- Laboratory of Biochemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124, Thessaloniki, Greece
| | - E Halevas
- Institute of Biosciences & Applications, National Centre for Scientific Research "Democritus", 15310, Athens, Greece
| | - E Geromichalou
- Laboratory of Pharmacology, Medical School, National and Kapodistrian University of Athens, 75 Mikras Asias Street, 11527, Athens, Greece
| | - G Geromichalos
- Laboratory of Biochemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124, Thessaloniki, Greece
| | - A A Pantazaki
- Laboratory of Biochemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54124, Thessaloniki, Greece.
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Yan R, Hu Y, Liu F, Wei S, Fang D, Shuhendler AJ, Liu H, Chen HY, Ye D. Activatable NIR Fluorescence/MRI Bimodal Probes for in Vivo Imaging by Enzyme-Mediated Fluorogenic Reaction and Self-Assembly. J Am Chem Soc 2019; 141:10331-10341. [PMID: 31244188 DOI: 10.1021/jacs.9b03649] [Citation(s) in RCA: 218] [Impact Index Per Article: 43.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Stimuli-responsive in situ self-assembly of small molecules to form nanostructures in living subjects has produced promising tools for molecular imaging and tissue engineering. However, controlling the self-assembly process to simultaneously activate multimodality imaging signals in a small-molecule probe is challenging. In this paper, we rationally integrate a fluorogenic reaction into enzyme-responsive in situ self-assembly to design small-molecule-based activatable near-infrared (NIR) fluorescence and magnetic resonance (MR) bimodal probes for molecular imaging. Using alkaline phosphatase (ALP) as a model target, we demonstrate that probe (P-CyFF-Gd) can be activated by endogenous ALP overexpressed on cell membranes, producing membrane-localized assembled nanoparticles (NPs) that can be directly visualized by cryo-SEM. Simultaneous enhancements in NIR fluorescence (>70-fold at 710 nm) and r1 relaxivity (∼2.3-fold) enable real-time, high-sensitivity, high-spatial-resolution imaging and localization of the ALP activity in live tumor cells and mice. P-CyFF-Gd can also delineate orthotopic liver tumor foci, facilitating efficient real-time, image-guided surgical resection of tumor tissues in intraoperative mice. This strategy combines activatable NIR fluorescence via a fluorogenic reaction and activatable MRI via in situ self-assembly to promote ALP activity imaging, which could be applicable to design other activatable bimodal probes for in vivo imaging of enzyme activity and locations in real time.
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Affiliation(s)
- Runqi Yan
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering , Nanjing University , Nanjing 210023 , China
| | - Yuxuan Hu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering , Nanjing University , Nanjing 210023 , China
| | - Fei Liu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering , Nanjing University , Nanjing 210023 , China
| | - Shixuan Wei
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering , Nanjing University , Nanjing 210023 , China
| | - Daqing Fang
- State Key Laboratory of Drug Research and Key Laboratory of Receptor Research , Shanghai Institute of Materia Medica, Chinese Academy of Sciences , 555 Zu Chong Zhi Road , Shanghai 201203 , China
| | - Adam J Shuhendler
- Department of Chemistry & Biomolecular Sciences , University of Ottawa , Ottawa , ON K1N 6N5 , Canada
| | - Hong Liu
- State Key Laboratory of Drug Research and Key Laboratory of Receptor Research , Shanghai Institute of Materia Medica, Chinese Academy of Sciences , 555 Zu Chong Zhi Road , Shanghai 201203 , China
| | - Hong-Yuan Chen
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering , Nanjing University , Nanjing 210023 , China
| | - Deju Ye
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering , Nanjing University , Nanjing 210023 , China.,Research Center for Environmental Nanotechnology (ReCent) , Nanjing University , Nanjing , 210023 , China
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Zhao G, Guo S, Jiang K, Zhang T, Wu H, Qiu C, Deng G. MiRNA profiling of plasma-derived exosomes from dairy cows during gestation. Theriogenology 2019; 130:89-98. [PMID: 30878693 DOI: 10.1016/j.theriogenology.2019.03.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 02/27/2019] [Accepted: 03/03/2019] [Indexed: 12/14/2022]
Abstract
Exosomes, one kind of extracellular vesicles, are released under abnormal and normal physiological conditions. An understanding of plasma-derived exosomal microRNA (miRNA) profiles during pregnancy will significantly contribute to knowledge of maternal-fetal communication in ruminants. In this study, we isolated plasma-derived exosomes from dairy cows during early (∼60 days, gestational day (G_D) 60), mid (∼150 days, G_D 150) and late (∼240 days, G_D 240) pregnancy. Exosomal miRNA profiles were revealed using RNA sequencing technology, and the abundance of exosomal miRNAs between each stage were compared. In the G_D150 vs. G_D60, G_D240 vs. G_D60 and G_D240 vs. G_D150stages, there were 23, 32 and 29 miRNAs, respectively, significantly differentially enriched. Significant annotations for protein binding and transport- or immunoregulatory-related categories or pathways were found for the predicted target genes of these miRNAs. In addition, we further identified specific exosomal miRNAs for each pregnancy stage, including the following: bta-miR-499, bta-miR-16a, bta-miR-20a, bta-miR-223, and bta-miR-128 in the G_D60 stage; bta-miR-493, bta-miR-127, and bta-miR-143 in the G_D150 stage; and bta-miR-122, bta-miR-182, bta-miR-183, bta-miR-200b, and bta-miR-200c in the G_D240 stage. Our findings provide new insight into maternal-fetal communication during pregnancy. Future studies will use these data to identify and characterize specific exosomal miRNA regulatory mechanisms in the maternal-fetal immune response.
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Affiliation(s)
- Gan Zhao
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Shuai Guo
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Kangfeng Jiang
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Tao Zhang
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Haichong Wu
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Changwei Qiu
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China
| | - Ganzhen Deng
- Department of Clinical Veterinary Medicine, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China.
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Drzazga A, Sowinska A, Krzeminska A, Rytczak P, Koziolkiewicz M, Gendaszewska-Darmach E. Lysophosphatidylcholine elicits intracellular calcium signaling in a GPR55-dependent manner. Biochem Biophys Res Commun 2017; 489:242-247. [PMID: 28552522 DOI: 10.1016/j.bbrc.2017.05.145] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2017] [Accepted: 05/24/2017] [Indexed: 01/28/2023]
Abstract
The GPR55 signaling is fertile ground for drug discovery, however despite considerable research progress during the past 10 years, many open questions remain. The GPR55 pharmacology remains controversial, as many ligands have been reported with inconsistent results. Here, we show that various molecular species of lysophosphatidylcholine (LPC) elicit intracellular Ca2+ mobilization in GPR55-expressing PC-3 human prostate carcinoma cells. The response was even stronger than [Ca2+]i flux evoked by endogenous (OEA) and synthetic (Abn-CBD) agonists. Treatment with GPR55 antagonists CID16020046 and ML193 as well as the lipid raft disrupter methyl-β-cyclodextrin strongly blunted LPC-induced calcium signal. Additionally, molecular modeling analysis revealed that LPC 16:0 and LPC 18:1 interact stronger with the receptor than to OEA. Identified electrostatic interactions between GPR55 residues and the ligands overlap with the binding site identified previously for lysophosphatidylinositol. Therefore, we prove that LPC is another GPR55-sensitive ligand. This finding is relevant in understanding lysophospolipids-mediated signaling and opens new avenues to develop therapeutic approach based on GPR55 targeting.
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Affiliation(s)
- Anna Drzazga
- Institute of Technical Biochemistry, Faculty of Biotechnology and Food Sciences, Lodz University of Technology, Stefanowskiego 4/10, 90-924 Lodz, Poland.
| | - Agata Sowinska
- Institute of Technical Biochemistry, Faculty of Biotechnology and Food Sciences, Lodz University of Technology, Stefanowskiego 4/10, 90-924 Lodz, Poland
| | - Agnieszka Krzeminska
- Institute of Applied Radiation Chemistry, Lodz University of Technology, Wroblewskiego 15, 93-590 Lodz, Poland
| | - Przemysław Rytczak
- Institute of Technical Biochemistry, Faculty of Biotechnology and Food Sciences, Lodz University of Technology, Stefanowskiego 4/10, 90-924 Lodz, Poland
| | - Maria Koziolkiewicz
- Institute of Technical Biochemistry, Faculty of Biotechnology and Food Sciences, Lodz University of Technology, Stefanowskiego 4/10, 90-924 Lodz, Poland
| | - Edyta Gendaszewska-Darmach
- Institute of Technical Biochemistry, Faculty of Biotechnology and Food Sciences, Lodz University of Technology, Stefanowskiego 4/10, 90-924 Lodz, Poland.
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Adsorption induced enzyme denaturation: The role of protein surface in adsorption induced protein denaturation on allyl glycidyl ether (AGE)–ethylene glycol dimethacrylate (EGDM) copolymers. Colloids Surf B Biointerfaces 2012; 90:184-90. [DOI: 10.1016/j.colsurfb.2011.10.022] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Revised: 10/10/2011] [Accepted: 10/12/2011] [Indexed: 11/18/2022]
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Chuang NN, Shih SL. Purification and some properties of alkaline phosphatase from the hepatopancreas of the shrimp Penaeus japonicus (Crustacea: Decapoda). ACTA ACUST UNITED AC 2010; 256:1-7. [PMID: 20509213 DOI: 10.1002/jez.1402560102] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Alkaline phosphatase purified from the hepatopancreas of Penaeus japonicus is stable to heating at 65 degree C for 5 min. The specific activity of the purified enzyme is 25,000 units/mg of protein. After polyacrylamide gel electrophoresis under denaturing conditions, the purified alkaline phosphatase from shrimp was found to consist of deglycosylated monomers of Mr 40,000 and to retain the attachment sites for both sialic acid and phosphatidylinositol. The alkaline phosphatase from shrimp has an isoelectric point (PI) of 7.6 and becomes more alkaline after the removal of either sialic acid or phosphatidylinositol residues.
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Affiliation(s)
- N N Chuang
- Division of Biochemistry and Molecular Science, Institute of Zoology,Academia Sinica, Nankang, Taipei, Republic of China
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Jain V, Saini D, Goswami P, Sinha S. A phage antibody to the active site of human placental alkaline phosphatase with higher affinity to the enzyme–substrate complex. Mol Immunol 2007; 44:369-76. [PMID: 16600380 DOI: 10.1016/j.molimm.2006.02.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2006] [Revised: 02/23/2006] [Accepted: 02/24/2006] [Indexed: 11/24/2022]
Abstract
Selection of specific antibodies from large repertoires is of importance in generating antibodies to specific structural determinants and in studying structure-function relationships. Alkaline phosphatase (AP) has several isozymes with various degrees of homology and a range of common synthetic substrates. We have previously reported the generation of isozyme specific anti-enzyme antibodies to an oncofetal antigen, placental alkaline phosphatase (PLAP) by using a specific uncompetitive inhibitor, L-Phe-Gly-Gly along with the substrate para-nitrophenyl phosphate (pNPP), to elute scFvs from a phage-displayed immunoglobulin library. These antibodies were directed to the active site and inhibited enzyme activity. An uncompetitive inhibitor acts by stabilizing the enzyme-substrate (ES) complex. In the present work, we report the characteristics of a clone VE5, selected by the same method. This clone has a higher binding affinity for ES complex than for enzyme alone. This is true for all the three isozymes (placental, bone and intestinal) tested. However, the other synthetic small molecular substrate, disodium phenyl phosphate inhibits phage binding. The clone possibly binds to the conserved structures of the active site of the AP isozymes and the higher affinity binding to AP-pNPP complex reflects the method of selection. Such anti-enzyme antibodies have a possible potential role in dissecting structure-function relationship of enzymatic antigens.
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Affiliation(s)
- Vishal Jain
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi 110029, India
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Saini D, Kala M, Jain V, Sinha S. Targeting the active site of the placental isozyme of alkaline phosphatase by phage-displayed scFv antibodies selected by a specific uncompetitive inhibitor. BMC Biotechnol 2005; 5:33. [PMID: 16372914 PMCID: PMC1351172 DOI: 10.1186/1472-6750-5-33] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2005] [Accepted: 12/22/2005] [Indexed: 11/10/2022] Open
Abstract
Background The isozymes of alkaline phosphatase, the tissue non-specific, intestinal and placental, have similar properties and a high degree of identity. The placental isozyme (PLAP) is an oncofetal antigen expressed in several malignancies including choriocarcinoma, seminoma and ovarian carcinoma. We had earlier attempted to isolate PLAP-specific scFv from a synthetic human immunoglobulin library but were unable to do so, presumably because of the similarity between the isozymes. In this work, we have employed a PLAP-specific uncompetitive inhibitor, L-Phe-Gly-Gly, to select isozyme specific scFvs. An uncompetitive inhibitor binds to the enzyme in the presence of substrate and stabilizes the enzyme-substrate complex. Several uncompetitive inhibitors have varying degrees of isozyme specificity for human alkaline phosphatase isozymes. A specific uncompetitive inhibitor would be able to unmask conformational differences between the otherwise very similar molecules. Also, such inhibitors would be directed to regions at/close to the active site of the enzyme. In this work, the library was first incubated with PLAP and the bound clones then eluted by incubation with L-Phe-Gly-Gly along with the substrate, para-nitro phenyl phosphate (pNPP). The scFvs were then studied with regard to the biochemical modulation of their binding, isozyme specificity and effect on enzyme activity. Results Of 13 clones studied initially, the binding of 9 was inhibited by L-Phe-Gly-Gly (with pNPP) and 2 clones were inhibited by pNPP alone. Two clones had absolute and 2 clones had partial specificity to PLAP. Two clones were cross-reactive with only one other isozyme. Three scFv clones, having an accessible His6-tag, were purified and studied for their modulation of enzyme activity. All the three scFvs inhibited PLAP activity with the kinetics of competitive inhibition. Cell ELISA could demonstrate binding of the specific scFvs to the cell surface expressed PLAP. Conclusion The results demonstrate the biochemical modulation of scFv binding. Also, the scFvs bound to the active site and denied the access to the substrate. The selection strategy could generate specific anti-enzyme antibodies to PLAP that can potentially be used for targeting, for modulating enzyme activity in in vitro and in vivo and as probes for the active site. This strategy also has a general application in selecting antibodies from combinatorial libraries to closely related molecules and conformations.
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Affiliation(s)
- Deepti Saini
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi-110029, India
- University of Arkansas for Medical Sciences, USA
| | - Mrinalini Kala
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi-110029, India
- University of California, San Francisco, USA
| | - Vishal Jain
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi-110029, India
| | - Subrata Sinha
- Department of Biochemistry, All India Institute of Medical Sciences, New Delhi-110029, India
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Asgeirsson B, Nielsen BN, Højrup P. Amino acid sequence of the cold-active alkaline phosphatase from Atlantic cod (Gadus morhua). Comp Biochem Physiol B Biochem Mol Biol 2003; 136:45-60. [PMID: 12941638 DOI: 10.1016/s1096-4959(03)00167-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Atlantic cod is a marine fish that lives at low temperatures of 0-10 degrees C and contains a cold-adapted alkaline phosphatase (AP). Preparations of AP from either the lower part of the intestines or the pyloric caeca area were subjected to proteolytic digestion, mass spectrometry and amino acid sequencing by Edman degradation. The primary structure exhibits greatest similarity to human tissue non-specific AP (80%), and approximately 30% similarity to AP from Escherichia coli. The key residues required for catalysis are conserved in the cod AP, except for the third metal binding site, where cod AP has the same variable residues as mammalian APs (His153 and His328 by E. coli AP numbering). General comparison of the amino acid composition with mammalian APs showed that cod AP contains fewer Cys, Leu, Met and Ser, but proportionally more Asn, Asp, Ile, Lys, Trp and Tyr residues. Three N-linked glycosylation sites were found. The glycan structure was determined as complex biantennary in type with fucose and sialic acid attached, although a trace of complex tri-antennary structure was also observed. A three-dimensional model was obtained by homology modelling using the human placental AP scaffold. Cod AP has fewer charged and hydrophobic residues, but more polar residues at the intersubunit surface. The N-terminal helix arm that embraces the second subunit in dimeric APs may be more flexible due to a replaced Pro at its base. One disulfide bridge was found instead of the two present in most other APs. This may invoke greater movement in the structure that together with weaker subunit contacts leads to improved catalytic efficiency.
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Affiliation(s)
- Bjarni Asgeirsson
- Department of Chemistry, Science Institute, University of Iceland, Dunhaga 3, Reykjavik IS-107, Iceland.
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Le Du MH, Lamoure C, Muller BH, Bulgakov OV, Lajeunesse E, Ménez A, Boulain JC. Artificial evolution of an enzyme active site: structural studies of three highly active mutants of Escherichia coli alkaline phosphatase. J Mol Biol 2002; 316:941-53. [PMID: 11884134 DOI: 10.1006/jmbi.2001.5384] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The crystal structure of three mutants of Escherichia coli alkaline phosphatase with catalytic activity (k(cat)) enhancement as compare to the wild-type enzyme is described in different states. The biological aspects of this study have been reported elsewhere. The structure of the first mutant, D330N, which is threefold more active than the wild-type enzyme, was determined with phosphate in the active site, or with aluminium fluoride, which mimics the transition state. These structures reveal, in particular, that this first mutation does not alter the active site. The second mutant, D153H-D330N, is 17-fold more active than the wild-type enzyme and activated by magnesium, but its activity drops after few days. The structure of this mutant was solved under four different conditions. The phosphate-free enzyme was studied in an inactivated form with zinc at site M3, or after activation by magnesium. The comparison of these two forms free of phosphate illustrates the mechanism of the magnesium activation of the catalytic serine residue. In the presence of magnesium, the structure was determined with phosphate, or aluminium fluoride. The drop in activity of the mutant D153H-D330N could be explained by the instability of the metal ion at M3. The analysis of this mutant helped in the design of the third mutant, D153G-D330N. This mutant is up to 40-fold more active than the wild-type enzyme, with a restored robustness of the enzyme stability. The structure is presented here with covalently bound phosphate in the active site, representing the first phosphoseryl intermediate of a highly active alkaline phosphatase. This study shows how structural analysis may help to progress in the improvement of an enzyme catalytic activity (k(cat)), and explains the structural events associated with this artificial evolution.
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Affiliation(s)
- M H Le Du
- Département d'Ingénierie et d'Etudes des Protéines, CEA, Saclay, Gif-sur-Yvette, France.
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14
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Park YD, Yang Y, Chen QX, Lin HN, Liu Q, Zhou HM. Kinetics of complexing activation by the magnesium ion on green crab (Scylla serrata) alkaline phosphatase. Biochem Cell Biol 2001. [DOI: 10.1139/o01-152] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
As with mammalian enzymes, green crab (Scylla serrata) alkaline phosphatase can be activated by Mg2+through a time-dependent course. The activation is mainly a Vmaxeffect. Tsou's method was used to study the kinetic course of activation. The results show that the enzyme was activated by a complexing scheme that had not been previously identified: the enzyme first reversibly and quickly binds Mg2+and then undergoes a slow reversible course to activation, with a relatively high activation energy (78 ± 4 kJ/mol) and a slow conformational change. The activation reaction is a single molecule reaction, and the apparent activation rate constant is independent of Mg2+concentration if the concentration is sufficiently high. The microscopic rate constants of activation and the association constant were determined from the measurements. The proposed scheme may also be applied to the Mg2+activation mechanism for mammalian enzyme, to explain why the activation rate is time-dependent and not diffusion controlled. Substrate binding was also shown to affect the activation rate constant.Key words: alkaline phosphatase, green crab, kinetics, activation, magnesium ion.
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15
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Bublitz R, Hoppe H, Cumme GA, Thiele M, Attey A, Horn A. Structural study on the carbohydrate moiety of calf intestinal alkaline phosphatase. JOURNAL OF MASS SPECTROMETRY : JMS 2001; 36:960-972. [PMID: 11523097 DOI: 10.1002/jms.200] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Surprisingly alkaline phosphatase (AP) (EC 3.1.3.1) of calf intestine is found in large amounts, e.g. 80%, within chyme. Most of the enzyme is present as a mixture of four differently hydrophobic anchor-bearing forms and only the minor part is present as an anchorless enzyme. To investigate whether changes in the N-glycosylation pattern are signals responsible for large-scale liberation from mucosa into chyme, the glycans of the two potential glycosylation sites predicted from cDNA were investigated by matrix-assisted laser desorption/ionization and electrospray ionization mass spectrometry in combination with exoglycosidase treatment after tryptic digestion and reversed-phase chromatography. The glycans linked to Asn249 are at least eight different, mainly non-fucosylated, biantennary or triantennary structures with a bisecting N-acetylglucosamine. For the most abundant glycopeptide (40%) the following glycan structure is proposed: [carbostructure: see text]. The glycans linked to Asn410 are a mixture of at least nine, mainly tetraantennary, fucosylated structures with a bisecting N-acetylglucosamine. For the most abundant glycopeptide (35%) the following glycan structure is proposed: [carbostructure: see text]. For the structures the linkage data were deduced from the reported specificities of the exoglycosidases used and the specificities of the transglycosidases active in biosynthesis. The majority of glycans are capped by alpha-galactose residues at their non-reducing termini. In contrast to the glycans linked to other AP isoenzymes, no sialylation was observed. Glycopeptide 'mass fingerprints' of both glycosylation sites and glycan contents do not differ between AP from mucosa and chyme. These results suggest that the observed large-scale liberation of vesicle-bound glycosylphosphatidylinositol (GPI)-anchored AP from mucosa into chyme is unlikely to be mediated by alteration of glycan structures of the AP investigated. Rather, the exocytotic vesicle formation seems to be mediated by the controlled organization of the raft structures embedding GPI-AP. (c) 2001 John Wiley & Sons, Ltd.
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Affiliation(s)
- R Bublitz
- Institute of Biochemistry, Medical Faculty, Friedrich Schiller University, D-07743 Jena, Germany
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16
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Abstract
A combination of approaches has begun to elucidate the mechanisms of gastrointestinal development. This review describes progress over the last 20 years in understanding human gastrointestinal development, including data from both human and experimental animal studies that address molecular mechanisms. Rapid progress is being made in the identification of genes regulating gastrointestinal development. Genes directing initial formation of the endoderm as well as organ-specific patterning are beginning to be identified. Signaling pathways regulating the overall right-left asymmetry of the gastrointestinal tract and epithelial-mesenchymal interactions are being clarified. In searching for extrinsic developmental regulators, numerous candidate trophic factors have been proposed, but compelling evidence remains elusive. A critical gene that initiates pancreas development has been identified, as well as a number of genes regulating liver, stomach, and intestinal development. Mutations in genes affecting neural crest cell migration have been shown to give rise to Hirschsprung's disease. Considerable progress has been achieved in understanding specific phenomena, such as the transcription factors regulating expression of sucrase-isomaltase and fatty acid-binding protein. The challenge for the future is to integrate these data into a more complete understanding of the physiology of gastrointestinal development.
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Affiliation(s)
- R K Montgomery
- Division of Pediatric Gastroenterology and Nutrition, The Floating Hospital for Children at New England Medical Center, Boston, MA 02111-1533, USA
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17
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Bublitz R, Armesto J, Hoffmann-Blume E, Schulze M, Rhode H, Horn A, Aulwurm S, Hannappel E, Fischer W. Heterogeneity of glycosylphosphatidylinositol-anchored alkaline phosphatase of calf intestine. EUROPEAN JOURNAL OF BIOCHEMISTRY 1993; 217:199-207. [PMID: 8223555 DOI: 10.1111/j.1432-1033.1993.tb18234.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A method is described for large-scale purification of glycosylphosphatidylinositol-anchored alkaline phosphatase from intestinal mucosa and chyme to homogeneity. Both enzyme preparations contain approximately 2 mol fatty acid/mol subunit and exhibit a very similar fatty acid composition with octadecanoate and hexadecanoate as prevalent components. No significant differences between native glycosylPtdIns-anchored and hydrophilic alkaline phosphatases from both sources were found regarding Km, Vmax, the type of inhibition and inhibition constants of the amino acids L-leucine, L-phenylalanine, and L-tryptophan. The purified enzymes of both sources yield diacylglycerol and phosphatidic acid, after treatment with phosphatidylinositol-specific phospholipase C (PtdIns-PLC) and glycosylphosphatidylinositol phospholipase D (PLD), respectively. Enzyme preparations of both sources appear as heterogeneous mixtures of five fractions separable by octyl-Sepharose chromatography. Fraction I corresponds to the anchorless enzyme, fractions II-V differ in their susceptibility to phospholipases. Fractions II and IV are completely split by PtdIns-PLC or PLD action, almost 50% of fraction III is split by PtdIns-PLC, while fraction V is resistant. The susceptibility of these two fractions toward the action of PLD is considerably higher. Fatty acid analysis yields molar ratios of fatty acids/alkaline phosphatase subunit of 1.78, 2.58, 2.24, and 3.37 for fractions II, III, IV, and V, respectively. Aggregates of glycosylPtdIns-anchored alkaline phosphatase of all fractions are seen in native PAGE in the presence of Triton X-100. By gel chromatography in the presence of Brij 35, fractions II-V form stable multiple aggregates of dimers and may bind different amounts of the detergent. These data, together with fatty acid analysis, can be interpreted by the following model. Fractions II and IV are tetramers and octamers with two molecules fatty acid/subunit. Fraction III is a tetramer, bearing one additional fatty acid molecule, localized on the dimer. Fraction V is an octamer, containing glycosylPtdIns-anchor molecules with three molecules fatty acids/anchor molecule. The additional fatty acid residue is possibly located on inositol and responsible for the reduced susceptibility to PtdIns-PLC. The similarity of all measured parameters of both enzymes suggests that the glycosylPtdIns-anchored alkaline phosphatase of the mucosa is released into the chyme without changing the anchor molecule constituents.
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Affiliation(s)
- R Bublitz
- Institute of Biochemistry, Medical Faculty, Friedrich Schiller University of Jena, Germany
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18
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Magnusson P, Löfman O, Larsson L. Determination of alkaline phosphatase isoenzymes in serum by high-performance liquid chromatography with post-column reaction detection. JOURNAL OF CHROMATOGRAPHY 1992; 576:79-86. [PMID: 1500460 DOI: 10.1016/0378-4347(92)80177-r] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A weak anion-exchange high-performance liquid chromatographic procedure with post-column reaction detection for simultaneous determination of alkaline phosphatase (EC 3.1.3.1, ALP) isoenzymes is described. We identified six peaks with ALP isoenzyme activity in normal serum. The peaks were, in order of elution, one intestinal/bone, two bone and three liver ALP isoenzymes. This new assay with automatic injection, on-line post-column reaction detection and powerful integration data system could be of significant value in the routine clinical biochemistry laboratory. The advantages include improved sensitivity and selectivity over previous methods for the determination of ALP isoenzymes.
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Affiliation(s)
- P Magnusson
- Department of Clinical Chemistry, University Hospital, Linköping, Sweden
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19
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Watanabe H, Tokuyama H, Ohta H, Satomura Y, Okai T, Ooi A, Mai M, Sawabu N. Expression of placental alkaline phosphatase in gastric and colorectal cancers. An immunohistochemical study using the prepared monoclonal antibody. Cancer 1990; 66:2575-82. [PMID: 2249198 DOI: 10.1002/1097-0142(19901215)66:12<2575::aid-cncr2820661221>3.0.co;2-q] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The authors developed monoclonal antibodies (MoAb) against human placental alkaline phosphatase (PLAP). Four specific MoAb reacting only with PLAP and two nonspecific MoAb reacting equally with isozymes of alkaline phosphatase (hepatic, intestinal, and placental) were obtained. Immunohistochemical staining with the specific MoAb showed that the cell membrane and cytoplasm of cancer cells were stained in gastric and colorectal carcinoma. The incidence of PLAP positivity was 23% (25 of 107) of all gastric carcinomas. Among gastric carcinomas, the 42% (13 of 31) positivity of highly differentiated carcinoma (papillary adenocarcinoma and well-differentiated tubular adenocarcinoma) was a significantly higher rate than that found in poorly differentiated carcinoma (poorly differentiated adenocarcinoma and signet-ring cell carcinoma, five of 41, 12%). The incidence of PLAP positivity was 11% (four of 35) in colorectal carcinoma. In contrast, gastric adenoma, intestinal metaplasia, and noncancerous tissue adjacent to cancer did not show staining. These results indicated that expression of PLAP was apt to occur in more highly differentiated gastric carcinoma and was highly specific for carcinoma in the gastrointestinal tract, although its incidence was not high.
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Affiliation(s)
- H Watanabe
- Department of Internal Medicine, Kanazawa University, Japan
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20
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Barsomian GD, Johnson TL, Borowski M, Denman J, Ollington JF, Hirani S, McNeilly DS, Rasmussen JR. Cloning and expression of peptide-N4-(N-acetyl-beta-D-glucosaminyl)asparagine amidase F in Escherichia coli. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)39245-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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21
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Watanabe S, Watanabe T, Li WB, Soong BW, Chou JY. Expression of the Germ Cell Alkaline Phosphatase Gene in Human Choriocarcinoma Cells. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)63900-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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22
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Alkaline phosphatase isozymes in the midgut of silkworm: purification of high pH-stable microvillus and labile cytosolic enzymes. J Comp Physiol B 1989. [DOI: 10.1007/bf00691732] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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23
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Fisher LW, Lindner W, Young MF, Termine JD. Synthetic peptide antisera: their production and use in the cloning of matrix proteins. Connect Tissue Res 1989; 21:43-8; discussion 49-50. [PMID: 2605953 DOI: 10.3109/03008208909049994] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Small amounts (0.1-1.0 nmole) of purified (greater than 90%) proteins isolated from small quantities of connective tissues can readily be microsequenced and 20 to 40 N-terminal amino acids determined. A synthetic peptide (10 or more amino acids long) can be produced and either injected directly into rabbits for antiserum production (generally peptides greater than 20 amino acids in length) or conjugated to a carrier protein prior to injection. The antisera have proven useful in the isolation of cDNA clones, for both locating clones producing the protein in expression libraries and in the subsequent confirmation of the sequence (preferably using a part of the sequence not directly used in the production of the original antiserum).
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Affiliation(s)
- L W Fisher
- Bone Research Branch, NIDR, Bethesda, MD
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24
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Henthorn PS, Raducha M, Kadesch T, Weiss MJ, Harris H. Sequence and characterization of the human intestinal alkaline phosphatase gene. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)37886-4] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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25
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Henthorn PS, Raducha M, Edwards YH, Weiss MJ, Slaughter C, Lafferty MA, Harris H. Nucleotide and amino acid sequences of human intestinal alkaline phosphatase: close homology to placental alkaline phosphatase. Proc Natl Acad Sci U S A 1987; 84:1234-8. [PMID: 3469665 PMCID: PMC304401 DOI: 10.1073/pnas.84.5.1234] [Citation(s) in RCA: 91] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
A cDNA clone for human adult intestinal alkaline phosphatase (ALP) [orthophosphoric-monoester phosphohydrolase (alkaline optimum); EC 3.1.3.1] was isolated from a lambda gt11 expression library. The cDNA insert of this clone is 2513 base pairs in length and contains an open reading frame that encodes a 528-amino acid polypeptide. This deduced polypeptide contains the first 40 amino acids of human intestinal ALP, as determined by direct protein sequencing. Intestinal ALP shows 86.5% amino acid identity to placental (type 1) ALP and 56.6% amino acid identity to liver/bone/kidney ALP. In the 3'-untranslated regions, intestinal and placental ALP cDNAs are 73.5% identical (excluding gaps). The evolution of this multigene enzyme family is discussed.
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26
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Berger J, Garattini E, Hua JC, Udenfriend S. Cloning and sequencing of human intestinal alkaline phosphatase cDNA. Proc Natl Acad Sci U S A 1987; 84:695-8. [PMID: 3468508 PMCID: PMC304282 DOI: 10.1073/pnas.84.3.695] [Citation(s) in RCA: 104] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Partial protein sequence data obtained on intestinal alkaline phosphatase indicated a high degree of homology with the reported sequence of the placental isoenzyme. Accordingly, placental alkaline phosphatase cDNA was cloned and used as a probe to clone intestinal alkaline phosphatase cDNA. The latter is somewhat larger (3.1 kilobases) than the cDNA for the placental isozyme (2.8 kilobases). Although the 3' untranslated regions are quite different, there is almost 90% homology in the translated regions of the two isozymes. There are, however, significant differences at their amino and carboxyl termini and a substitution of an alanine in intestinal alkaline phosphatase for a glycine in the active site of the placental isozyme.
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27
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Weiss MJ, Henthorn PS, Lafferty MA, Slaughter C, Raducha M, Harris H. Isolation and characterization of a cDNA encoding a human liver/bone/kidney-type alkaline phosphatase. Proc Natl Acad Sci U S A 1986; 83:7182-6. [PMID: 3532105 PMCID: PMC386679 DOI: 10.1073/pnas.83.19.7182] [Citation(s) in RCA: 268] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Alkaline phosphatases (ALPs) [orthophosphoric-monoester phosphohydrolase (alkaline optimum), EC 3.1.3.1] isolated from human liver, bone, and kidney (L/B/K) exhibit very similar biochemical and immunologic properties that differentiate them from other human ALPs, such as those characteristically found in placenta and intestine. Despite their similarities, the L/B/K ALPs produced in different tissues show slight physical differences. To examine structural and evolutionary relationships between the various ALPs, a cDNA corresponding to L/B/K ALP mRNA has been isolated. A lambda 11 cDNA expression library was constructed using poly(A) RNA from the osteosarcoma cell line Saos-2 and screened with anti-liver ALP antiserum. The 2553-base-pair cDNA contains an open reading frame that encodes a 524 amino acid polypeptide with a predicted molecular mass of 57.2 kDa. This ALP precursor protein contains a presumed signal peptide of 17 amino acids followed by 37 amino acids that are identical to the amino-terminal sequence determined from purified liver ALP. In addition, amino acid sequences of several CNBr peptides obtained from liver ALP are found within the cDNA-encoded protein. The deduced L/B/K ALP precursor polypeptide shows 52% homology to human placental ALP and 25% homology to Escherichia coli ALP precursor polypeptides. Sixty percent nucleotide homology exists between the human L/B/K and placental cDNAs over the protein coding regions. The 5' and 3' untranslated regions of the L/B/K ALP cDNA, 176 and 805 base pairs, respectively, show no homology to the corresponding regions of placental ALP cDNA.
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