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Lu JQ, Zhu ZN, Zheng YT, Shaw PC. Engineering of Ribosome-inactivating Proteins for Improving Pharmacological Properties. Toxins (Basel) 2020; 12:toxins12030167. [PMID: 32182799 PMCID: PMC7150887 DOI: 10.3390/toxins12030167] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 03/05/2020] [Accepted: 03/06/2020] [Indexed: 12/23/2022] Open
Abstract
Ribosome-inactivating proteins (RIPs) are N-glycosidases, which depurinate a specific adenine residue in the conserved α-sarcin/ricin loop (α-SRL) of rRNA. This loop is important for anchoring elongation factor (EF-G for prokaryote or eEF2 for eukaryote) in mRNA translocation. Translation is inhibited after the attack. RIPs therefore may have been applied for anti-cancer, and anti-virus and other therapeutic applications. The main obstacles of treatment with RIPs include short plasma half-life, non-selective cytotoxicity and antigenicity. This review focuses on the strategies used to improve the pharmacological properties of RIPs on human immunodeficiency virus (HIV) and cancers. Coupling with polyethylene glycol (PEG) increases plasma time and reduces antigenicity. RIPs conjugated with antibodies to form immunotoxins increase the selective toxicity to target cells. The prospects for future development on the engineering of RIPs for improving their pharmacological properties are also discussed.
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Affiliation(s)
- Jia-Qi Lu
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong 99077, China; (J.-Q.L.); (Z.-N.Z.)
| | - Zhen-Ning Zhu
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong 99077, China; (J.-Q.L.); (Z.-N.Z.)
| | - Yong-Tang Zheng
- Key Laboratory of Animal Models and Human Disease Mechanisms, National Kunming High level Biosafety Research Center for Non-human Primates, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, Yunnan, China;
| | - Pang-Chui Shaw
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong 99077, China; (J.-Q.L.); (Z.-N.Z.)
- Correspondence:
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Ling C, Zhang Y, Li J, Chen W, Ling C. Clinical Use of Toxic Proteins and Peptides from Tian Hua Fen and Scorpion Venom. Curr Protein Pept Sci 2019; 20:285-295. [PMID: 29932034 DOI: 10.2174/1389203719666180622100641] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2018] [Revised: 04/10/2018] [Accepted: 05/22/2018] [Indexed: 12/16/2022]
Abstract
Traditional Chinese Medicine (TCM) has been practiced in China for thousands of years. As a complementary and alternative treatment, herbal medicines that are frequently used in the TCM are the most accepted in the Western world. However, animal materials, which are equally important in the TCM practice, are not well-known in other countries. On the other hand, the Chinese doctors had documented the toxic profiles of hundreds of animals and plants thousand years ago. Furthermore, they saw the potential benefits of these materials and used their toxic properties to treat a wide variety of diseases, such as heavy pain and cancer. Since the 50s of the last century, efforts of the Chinese government and societies to modernize TCM have achieved tremendous scientific results in both laboratory and clinic. A number of toxic proteins have been isolated and their functions identified. Although most of the literature was written in Chinese, this review provide a summary, in English, regarding our knowledge of the clinical use of the toxic proteins isolated from a plant, Tian Hua Fen, and an animal, scorpion, both of which are famous toxic prescriptions in TCM.
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Affiliation(s)
- Chen Ling
- Division of Cellular and Molecular Therapy, Department of Pediatrics, College of Medicine, University of Florida, Gainesville 32611, Florida, FL, United States
| | - Yuanhui Zhang
- Department of Oncology, Baoshan Hospital of Integrated Traditional Chinese Medicine and Western Medicine, Shanghai 201999, China
| | - Jun Li
- Division of Cellular and Molecular Therapy, Department of Pediatrics, College of Medicine, University of Florida, Gainesville 32611, Florida, FL, United States.,Department of Traditional Chinese Medicine, Changhai Hospital, Second Military Medical University, Shanghai 200433, China
| | - Wenli Chen
- Department of Oncology, Baoshan Hospital of Integrated Traditional Chinese Medicine and Western Medicine, Shanghai 201999, China
| | - Changquan Ling
- Department of Traditional Chinese Medicine, Changhai Hospital, Second Military Medical University, Shanghai 200433, China.,E-institute of Internal Medicine of Traditional Chinese Medicine, Shanghai Municipal Education Commission, Shanghai 201203, China
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Giansanti F, Flavell DJ, Angelucci F, Fabbrini MS, Ippoliti R. Strategies to Improve the Clinical Utility of Saporin-Based Targeted Toxins. Toxins (Basel) 2018; 10:toxins10020082. [PMID: 29438358 PMCID: PMC5848183 DOI: 10.3390/toxins10020082] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2017] [Revised: 01/29/2018] [Accepted: 02/11/2018] [Indexed: 02/06/2023] Open
Abstract
Plant Ribosome-inactivating proteins (RIPs) including the type I RIP Saporin have been used for the construction of Immunotoxins (ITxs) obtained via chemical conjugation of the toxic domain to whole antibodies or by generating genetic fusions to antibody fragments/targeting domains able to direct the chimeric toxin against a desired sub-population of cancer cells. The high enzymatic activity, stability and resistance to conjugation procedures and especially the possibility to express recombinant fusions in yeast, make Saporin a well-suited tool for anti-cancer therapy approaches. Previous clinical work on RIPs-based Immunotoxins (including Saporin) has shown that several critical issues must be taken into deeper consideration to fully exploit their therapeutic potential. This review focuses on possible combinatorial strategies (chemical and genetic) to augment Saporin-targeted toxin efficacy. Combinatorial approaches may facilitate RIP escape into the cytosolic compartment (where target ribosomes are), while genetic manipulations may minimize potential adverse effects such as vascular-leak syndrome or may identify T/B cell epitopes in order to decrease the immunogenicity following similar strategies as those used in the case of bacterial toxins such as Pseudomonas Exotoxin A or as for Type I RIP Bouganin. This review will further focus on strategies to improve recombinant production of Saporin-based chimeric toxins.
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Affiliation(s)
- Francesco Giansanti
- Department of Life, Health and Environmental Sciences, University of L'Aquila, I-67100 L'Aquila, Italy.
| | - David J Flavell
- The Simon Flavell Leukaemia Research Laboratory (Leukaemia Busters), Southampton General Hospital, Southampton, SO16 8AT, UK.
| | - Francesco Angelucci
- Department of Life, Health and Environmental Sciences, University of L'Aquila, I-67100 L'Aquila, Italy.
| | | | - Rodolfo Ippoliti
- Department of Life, Health and Environmental Sciences, University of L'Aquila, I-67100 L'Aquila, Italy.
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Chang CD, Lin PY, Chen YC, Huang HH, Shih WL. Novel purification method and antibiotic activity of recombinant Momordica charantia MAP30. 3 Biotech 2017; 7:3. [PMID: 28389897 PMCID: PMC5383789 DOI: 10.1007/s13205-016-0590-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 12/19/2016] [Indexed: 11/24/2022] Open
Abstract
Ribosome-inactivating proteins (RIPs) are a group of enzymes originally isolated from plants that possess the ability to damage ribosomes in an irreversible manner, leading to inhibition of protein synthesis in eukaryotic cells. In this study, we aimed to purify recombinant RIPs, investigate their function in the treatment of bacterial infection, and determine their toxicity in mice. We employed a pMAL protein fusion and purification system using E. coli transformed with a plasmid containing MBP-tagged MAP30 cDNA. MBP-tagged MAP30 was purified using a modified novel protocol to effectively produce highly active MAP30 of high purity. In an acute toxicity study in mice, no mortality occurred at doses lower than 1.25 mg/kg. MAP30 at both 0.42 and 0.14 mg/kg induced anti-MAP30 IgG, which reached a maximum titer at week 3. In conclusion, recombinant MAP30 prepared using our purification method possesses bioactivity, and has a synergistic bacteria-killing effect that can significantly reduce the required dosages of chloramphenicol and erythromycin. Therefore, when MAP30 is used in combination with chloramphenicol or erythromycin, it may of benefit in terms of reducing the side effects of the antibiotics, as lower concentrations of antibiotics are required.
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Affiliation(s)
- Ching-Dong Chang
- Department of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, Taiwan
| | - Ping-Yuan Lin
- Department of Biological Science and Technology, National Pingtung University of Science and Technology, 1, Shuefu Rd., Neipu, Pingtung, 91201, Taiwan
| | - Yo-Chia Chen
- Department of Biological Science and Technology, National Pingtung University of Science and Technology, 1, Shuefu Rd., Neipu, Pingtung, 91201, Taiwan
| | - Han-Hsiang Huang
- Department of Veterinary Medicine, National Chiayi University, Chiayi City, Taiwan
| | - Wen-Ling Shih
- Department of Biological Science and Technology, National Pingtung University of Science and Technology, 1, Shuefu Rd., Neipu, Pingtung, 91201, Taiwan.
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Yang GL, Li SM, Wang SZ. Research progress in enzyme activity and pharmacological effects of ribosome-inactivity protein in bitter melon. TOXIN REV 2016. [DOI: 10.1080/15569543.2016.1185734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Zhang XY, Wu Y, Yan JY, Gao Y, Wang Y, Mi SL, An CC. Y55 and D78 are crucial amino acid residues of a new IgE epitope on trichosanthin. Biochem Biophys Res Commun 2006; 343:1251-6. [PMID: 16581017 DOI: 10.1016/j.bbrc.2006.03.097] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2006] [Accepted: 03/16/2006] [Indexed: 10/24/2022]
Abstract
Trichosanthin (TCS) possesses many biological and pharmaceutical activities, but its strong immunogenicity limits its clinical application. To reduce the immunogenicity of TCS, we modified the reported method for the prediction of antigenic site and identified two crucial amino acid residues (Y55 and D78) for a new epitope. We mutated these two residues into glycine and serine, respectively, and obtained three mutants, Y55G, D78S, and Y55G/D78S. These mutants induced less amount of Ig and IgG antibodies in C57BL/6J mice than wild-type TCS (wTCS) (p<0.01) and almost lost the ability to induce IgE antibody production. The mutants stimulated fewer TCS-specific B cells in C57BL/6J mice than wTCS (p<0.01). Compared with wTCS, Y55G, D78S, and Y55G/D78S lost 26.9%, 17.9%, and 98.7% specific binding ability to anti-TCS monoclonal antibody TCS4E9, respectively. These mutants still retained RNA N-glycosidase activity. In conclusion, Y55 and D78 are two crucial amino acid residues of a new IgE epitope on TCS, and their mutation reduces the immunogenicity of TCS, but still retained the enzymatic activity.
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Affiliation(s)
- Xin-Yue Zhang
- The National Laboratory of Protein Engineering and Plant Genetic Engineering, College of Life Sciences, Peking University, Beijing 100871, PR China
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Huang H, Chan H, Wang YY, Ouyang DY, Zheng YT, Tam SC. Trichosanthin suppresses the elevation of p38 MAPK, and Bcl-2 induced by HSV-1 infection in Vero cells. Life Sci 2006; 79:1287-92. [PMID: 16725160 DOI: 10.1016/j.lfs.2006.03.047] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2005] [Revised: 03/11/2006] [Accepted: 03/28/2006] [Indexed: 11/21/2022]
Abstract
Trichosanthin (TCS) is a type 1 ribosome-inactivating protein (RIP) effective against HIV-1 and HSV-1 replication. The mechanism of its antiviral activity is not clear. Many believe that it is related to ribosome inactivation. Some RIPs and viral infection affect the phosphorylation of MAPK and Bcl-2 and these proteins may be the common element linking RIP and viral infection. This study investigated the effect of HSV-1 infection on p38 MAPK and Bcl-2 as well as possible interference by TCS. Results showed that HSV-1 infection induced an elevation of phosphorylated p38 and Bcl-2 in Vero cells, which could be partially blocked by TCS. At the same time, both viral replication and host cells viability were lowered. Viral replication, Vero cell viability, p38 MAPK and Bcl-2 were further reduced with the addition of a p38 MAPK inhibitor (SB203580). This suggested that TCS may interfere with MAPK and Bcl-2 signals generated by infection leading to inhibition of viral replication. In summary, our results demonstrated that HSV-1 infection in Vero cells induced an elevation of p38 MAPK and Bcl-2. TCS suppressed this rise and reduced viral replication. The MAPK family may play a role in the antiviral mechanism of TCS.
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Affiliation(s)
- Hai Huang
- Department of Physiology, The Chinese University of Hong Kong, Hong Kong SAR, China
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Wang YY, Ouyang DY, Huang H, Chan H, Tam SC, Zheng YT. Enhanced apoptotic action of trichosanthin in HIV-1 infected cells. Biochem Biophys Res Commun 2005; 331:1075-80. [PMID: 15882987 DOI: 10.1016/j.bbrc.2005.03.230] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2005] [Indexed: 11/27/2022]
Abstract
Trichosanthin (TCS) is a type 1 ribosome-inactivating protein (RIP) effective against HIV-1 replication. The mechanism is not clear. Present results suggested that the antiviral action may be partly mediated through enhanced apoptosis on infected cells. TCS induced apoptosis in normal H9 cells and this action was more potent in those infected with HIV-1. In flow cytometry study, TCS induced larger population of apoptotic H9 cells chronically infected with HIV-1 in a dose-dependent manner. At TCS concentration of 25 microg/ml, 8.4% of normal H9 cells were found to be apoptotic whereas the same concentration induced 24.5% in HIV-1 chronically infected cells. Such difference was not found in the control experiments without TCS treatment. Two other studies supported this action. Cytotoxic study showed that cell viability was always lower in HIV-1 infected cells after TCS treatment, and DNA fragmentation study confirmed more laddering in infected cells. The mechanism of TCS induced apoptosis in normal or infected H9 cells is not clear. Results in this study demonstrated that TCS is more effective in inducing apoptosis in HIV-1 infected cells. This may explain in part the antiviral action of TCS.
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Affiliation(s)
- Yuan-Yuan Wang
- Laboratory of Molecular Immunopharmacology, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China
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Chan HM, Tam SC. Role of blood transfusion in trichosanthin-induced anaphylaxis. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2005; 20:73-76. [PMID: 21783570 DOI: 10.1016/j.etap.2004.10.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2004] [Accepted: 10/21/2004] [Indexed: 05/31/2023]
Abstract
Trichosanthin (TCS) is a type 1 ribosome inactivating protein extracted from Chinese medicinal herb. It possesses various biological functions such as abortifacient, anti-tumor and anti-viral activities. Clinical trial of this compound against human immunodeficiency virus (HIV) had been conducted. However, its use is limited by its high immunogenicity that elicits hypersensitivity reaction. This may lead to fatal anaphylactic response. The study described an approach of using blood transfusion to reduce TCS induced anaphylaxis in rats using a cross-circulation model. A TCS-sensitized Sprague Dawley rat was connected to a normal rat via the femoral vessels in a cross-circulation circuit before antigenic challenge. The donor rat served as a blood exchange basin to lower the level of the blood-borne components responsible for the anaphylactic reaction in the sensitized rat. Our results showed that cross-circulation shortened the duration of circulatory hypotension and reduced mortality of TCS induced anaphylaxis. The control group not undergoing cross-circulation had a mortality of 50% at 2h post-TCS challenge and there was no mortality in the cross-circulation group. This demonstrated that prior blood transfusion can be one of the alternatives to reduce anaphylactic response of TCS.
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Affiliation(s)
- H M Chan
- Department of Physiology, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong, PR China
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Shaw PC, Lee KM, Wong KB. Recent advances in trichosanthin, a ribosome-inactivating protein with multiple pharmacological properties. Toxicon 2005; 45:683-9. [PMID: 15804517 DOI: 10.1016/j.toxicon.2004.12.024] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2004] [Accepted: 12/24/2004] [Indexed: 11/22/2022]
Abstract
Trichosanthin (TCS), a ribosome-inactivating protein extracted from the root tuber of Chinese medicinal herb Trichosanthes kirilowii Maximowicz, has multiple pharmacological properties including abortifacient, anti-tumor and anti-HIV. It is traditionally used to induce abortion but its antigenicity and short plasma half-life have limited the repeated clinical administration. In this review, work to locating antigenic sites and prolonging plasma half-life are discussed. Studies on structure-function relationship and mechanism of cell entry are also covered. Recently, TCS has been found to induce apoptosis, enhance the action of chemokines and inhibit HIV-1 integrase. These findings give new insights on the pharmacological properties of TCS and other members of ribosome-inactivating proteins.
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Affiliation(s)
- Pang-Chui Shaw
- Department of Biochemistry, Centre for Protein Science and Crystallography, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China.
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Wang JH, Tam SC, Huang H, Ouyang DY, Wang YY, Zheng YT. Site-directed PEGylation of trichosanthin retained its anti-HIV activity with reduced potency in vitro. Biochem Biophys Res Commun 2004; 317:965-71. [PMID: 15094363 DOI: 10.1016/j.bbrc.2004.03.139] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2004] [Indexed: 11/20/2022]
Abstract
Trichosanthin (TCS) was the first ribosome inactivating protein found to possess anti-HIV-1 activity. Phase I/II clinical trial of this compound had been done. Antigenicity and short plasma half-life were the major side effects preventing further clinical trial. Modification of TCS is therefore necessary to revive the interest to develop this compound as an anti-HIV agent. Three potential antigenic sites (Ser-7, Lys-173, and Gln-219) were identified by computer modeling. Through site-directed mutagenesis, these three antigenic amino acids were mutated to a cysteine residue resulting in 3 TCS mutants, namely S7C, K173C, and Q219C. These mutants were further coupled to polyethylene glycol with a molecular size of 20kDa (PEG) via the cysteine residue. This produced another three TCS derivatives, namely PEG20k-S7C, PEG20k-K173C, and PEG20k-Q219C. PEGylation had been widely used recently to decrease immunogenicity by masking the antigenic sites and prolong plasma half-life by expanding the molecular size. The in vitro anti-HIV-1 activity of these mutants and derivatives was tested. Results showed that the anti-HIV-1 activity of S7C, K173C, and Q219C was decreased by about 1.5- to 5.5-fold with slightly lower cytotoxicity. On the other hand, PEGylation produced larger decrease (20- to 30-fold) in anti-HIV activity. Cytotoxicity was, however, weakened only slightly by about 3-fold. The in vitro study showed that the anti-HIV activity of PEGylated TCS was retained with reduced potency. The in vivo activity is expected to have only slightly changed due to other beneficial effects like prolonged half-life.
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Affiliation(s)
- Jian-Hua Wang
- Laboratory of Molecular Immunopharmacology, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, PR China
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Chan SH, Hung FS, Chan DS, Shaw PC. Trichosanthin interacts with acidic ribosomal proteins P0 and P1 and mitotic checkpoint protein MAD2B. EUROPEAN JOURNAL OF BIOCHEMISTRY 2001; 268:2107-12. [PMID: 11277934 DOI: 10.1046/j.1432-1327.2001.02091.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Trichosanthin is a ribosome-inactivating protein with multiple pharmacological properties. By a yeast two-hybrid system, ribosomal phosphoproteins P0 and P1 and a putative mitotic checkpoint protein, MAD2B, were found to interact with an active-site mutated trichosanthin (TCS). The interactions were verified by an in vitro binding assay of recombinant wild-type TCS and target proteins. The interaction domain of P0 was mapped to amino acids 220-273, which had been previously reported to be involved in the interaction with P1 and P2 in yeast. Consistent with our previous finding that the last seven residues of TCS are not essential for an active conformation, the same deletion did not affect the interaction with P0. Our present study suggests that TCS may disrupt the binding of elongation factors to the P-complex, in addition to the well-known N-glycosidase activity for ribosome inactivation.
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Affiliation(s)
- S H Chan
- Department of Biochemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
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Abstract
Dextrans are glucose polymers which have been used for more than 50 years as plasma volume expanders. Recently, however, dextrans have been investigated for delivery of drugs, proteins/enzymes, and imaging agents. These highly water soluble polymers are available commercially as different molecular weights (M(W)) with a relatively narrow M(W) distribution. Additionally, dextrans contain a large number of hydroxyl groups which can be easily conjugated to drugs and proteins by either direct attachment or through a linker. In terms of pharmacokinetics, the intact polymer is not absorbed to a significant degree after oral administration. Therefore, most of the applications of dextrans as macromolecular carriers are through injectable routes. However, a few studies have reported the potential of dextrans for site (colon)-specific delivery of drugs via the oral route. After the systemic administration, the pharmacokinetics of the conjugates of dextran with therapeutic/imaging agents are significantly affected by the kinetics of the dextran carrier. Animal and human studies have shown that both the distribution and elimination of dextrans are dependent on the M(W) and charge of these polymers. Pharmacodynamically, conjugation with dextrans has resulted in prolongation of the effect, alteration of toxicity profile, and a reduction in the immunogenicity of drugs and/or proteins. A substantial number of studies on dextran conjugates of therapeutic/imaging agents have reported favorable alteration of pharmacokinetics and pharmacodynamics of these agents. However, most of these studies have been carried out in animals, with only a few being extended to humans. Future studies should concentrate on barriers for the clinical use of dextrans as macromolecular carriers for delivery of drugs, proteins, and imaging agents.
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Affiliation(s)
- R Mehvar
- School of Pharmacy, Texas Tech University Health Sciences Center, 1300 Coulter, Amarillo, TX 79106, USA.
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He XH, Shaw PC, Xu LH, Tam SC. Site-directed polyethylene glycol modification of trichosanthin: effects on its biological activities, pharmacokinetics, and antigenicity. Life Sci 1999; 64:1163-75. [PMID: 10210259 DOI: 10.1016/s0024-3205(99)00048-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Trichosanthin (TCS), a type I ribosome-inactivating protein (RIP), was modified with polyethylene glycol (PEG) in order to reduce its antigenicity and prolong its half-life. Computer modeling identified three potential antigenic sites namely Q219, K173 and S7. By site-directed mutagenesis, these sites were changed into cysteine through which PEG can be covalently attached. The resulting TCS had a PEG coupled directly above one of its potential antigenic determinants, hence masking the antigenic region and prevent binding of antibodies specific to this site. In general, mutation did not bring about significant changes in ribosome-inactivating activity, cytotoxicity, and abortifacient activity of TCS. However, the in vitro activities of PEG modified (PEGylated) TCS muteins were 3-20 folds lower and the in vivo activity 50% less than that of nTCS. Pharmacokinetics study indicated that all three PEGylated TCS muteins showed 6-fold increase in mean residence time as compared to unmodified muteins. The binding affinity of an IgE monoclonal antibody (TE1) to TCS was greatly reduced after PEG modification (PEGylation) at position Q219, suggesting that TE1 recognized an epitope very near to residue Q219. PEGylated TCS muteins induced similar IgG response but 4-16 fold lower IgE response in mice compared with nTCS.
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Affiliation(s)
- X H He
- Department of Physiology, The Chinese University of Hong Kong, Shatin, NT
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