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Choi SR, Talmon GA, Hearne K, Woo J, Truong VL, Britigan BE, Narayanasamy P. Combination Therapy with Gallium Protoporphyrin and Gallium Nitrate Exhibits Enhanced Antimicrobial Activity In Vitro and In Vivo against Methicillin-Resistant Staphylococcus aureus. Mol Pharm 2023; 20:4058-4070. [PMID: 37471668 DOI: 10.1021/acs.molpharmaceut.3c00223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/22/2023]
Abstract
There is a major need for the development of new therapeutics to combat antibiotic-resistant Staphylococcus aureus. Recently, gallium (Ga)-based complexes have shown promising antimicrobial effects against various bacteria, including multidrug-resistant organisms, by targeting multiple heme/iron-dependent metabolic pathways. Among these, Ga protoporphyrin (GaPP) inhibits bacterial growth by targeting heme pathways, including aerobic respiration. Ga(NO3)3, an iron mimetic, disrupts elemental iron pathways. Here, we demonstrate the enhanced antimicrobial activity of the combination of GaPP and Ga(NO3)3 against methicillin-resistant S. aureus (MRSA) under iron-limited conditions, including small colony variants (SCV). This therapy demonstrated significant antimicrobial activity without inducing slow-growing SCV. We also observed that the combination of GaPP and Ga(NO3)3 inhibited the MRSA catalase but not above that seen with Ga(NO3)3 alone. Neither GaPP nor Ga(NO3)3 alone or their combination inhibited the dominant superoxide dismutase expressed (SodA) under the iron-limited conditions examined. Intranasal administration of the combination of the two compounds improved drug biodistribution in the lungs compared to intraperitoneal administration. In a murine MRSA lung infection model, we observed a significant increase in survival and decrease in MRSA lung CFUs in mice that received combination therapy with intranasal GaPP and Ga(NO3)3 compared to untreated control or mice receiving GaPP or Ga(NO3)3 alone. No drug-related toxicity was observed as assessed histologically in the spleen, lung, nasal cavity, and kidney for both single and repeated doses of 10 mg Ga /Kg of mice over 13 days. Our results strongly suggest that GaPP and Ga(NO3)3 in combination have excellent synergism and potential to be developed as a novel therapy for infections with S. aureus.
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Affiliation(s)
- Seoung-Ryoung Choi
- Department of Pathology and Microbiology, College of Medicine, University of Nebraska Medical Center, Omaha, Nebraska 68198, United States
| | - Geoffrey A Talmon
- Department of Pathology and Microbiology, College of Medicine, University of Nebraska Medical Center, Omaha, Nebraska 68198, United States
| | - Kenneth Hearne
- Aridis Pharmaceuticals, Los Gatos, California 95032, United States
| | - Jennifer Woo
- Aridis Pharmaceuticals, Los Gatos, California 95032, United States
| | - Vu L Truong
- Aridis Pharmaceuticals, Los Gatos, California 95032, United States
| | - Bradley E Britigan
- Department of Pathology and Microbiology, College of Medicine, University of Nebraska Medical Center, Omaha, Nebraska 68198, United States
- Department of Internal Medicine, College of Medicine, University of Nebraska Medical Center, Omaha, Nebraska 68198, United States
- Department of Internal Medicine and Research Service, Veterans Affairs Medical Center-Nebraska Western Iowa, Omaha, Nebraska 68105, United States
| | - Prabagaran Narayanasamy
- Department of Pathology and Microbiology, College of Medicine, University of Nebraska Medical Center, Omaha, Nebraska 68198, United States
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Piepenbrink MS, Park JG, Deshpande A, Loos A, Ye C, Basu M, Sarkar S, Khalil AM, Chauvin D, Woo J, Lovalenti P, Erdmann NB, Goepfert PA, Truong VL, Bowen RA, Walter MR, Martinez-Sobrido L, Kobie JJ. Potent universal beta-coronavirus therapeutic activity mediated by direct respiratory administration of a Spike S2 domain-specific human neutralizing monoclonal antibody. PLoS Pathog 2022; 18:e1010691. [PMID: 35862475 PMCID: PMC9302814 DOI: 10.1371/journal.ppat.1010691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 06/21/2022] [Indexed: 11/20/2022] Open
Abstract
Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) marks the third novel β-coronavirus to cause significant human mortality in the last two decades. Although vaccines are available, too few have been administered worldwide to keep the virus in check and to prevent mutations leading to immune escape. To determine if antibodies could be identified with universal coronavirus activity, plasma from convalescent subjects was screened for IgG against a stabilized pre-fusion SARS-CoV-2 spike S2 domain, which is highly conserved between human β-coronavirus. From these subjects, several S2-specific human monoclonal antibodies (hmAbs) were developed that neutralized SARS-CoV-2 with recognition of all variants of concern (VoC) tested (Beta, Gamma, Delta, Epsilon, and Omicron). The hmAb 1249A8 emerged as the most potent and broad hmAb, able to recognize all human β-coronavirus and neutralize SARS-CoV and MERS-CoV. 1249A8 demonstrated significant prophylactic activity in K18 hACE2 mice infected with SARS-CoV-2 lineage A and lineage B Beta, and Omicron VoC. 1249A8 delivered as a single 4 mg/kg intranasal (i.n.) dose to hamsters 12 hours following infection with SARS-CoV-2 Delta protected them from weight loss, with therapeutic activity further enhanced when combined with 1213H7, an S1-specific neutralizing hmAb. As little as 2 mg/kg of 1249A8 i.n. dose 12 hours following infection with SARS-CoV Urbani strain, protected hamsters from weight loss and significantly reduced upper and lower respiratory viral burden. These results indicate in vivo cooperativity between S1 and S2 specific neutralizing hmAbs and that potent universal coronavirus neutralizing mAbs with therapeutic potential can be induced in humans and can guide universal coronavirus vaccine development.
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Affiliation(s)
- Michael S. Piepenbrink
- Department of Medicine, Division of Infectious Diseases, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Jun-Gyu Park
- Texas Biomedical Research Institute, San Antonio, Texas, United States of America
| | - Ashlesha Deshpande
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Andreas Loos
- Aridis Pharmaceuticals Inc., Los Gatos, California, United States of America
| | - Chengjin Ye
- Texas Biomedical Research Institute, San Antonio, Texas, United States of America
| | - Madhubanti Basu
- Department of Medicine, Division of Infectious Diseases, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Sanghita Sarkar
- Department of Medicine, Division of Infectious Diseases, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Ahmed Magdy Khalil
- Texas Biomedical Research Institute, San Antonio, Texas, United States of America
| | - David Chauvin
- Aridis Pharmaceuticals Inc., Los Gatos, California, United States of America
| | - Jennifer Woo
- Aridis Pharmaceuticals Inc., Los Gatos, California, United States of America
| | - Philip Lovalenti
- Aridis Pharmaceuticals Inc., Los Gatos, California, United States of America
| | - Nathaniel B. Erdmann
- Department of Medicine, Division of Infectious Diseases, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Paul A. Goepfert
- Department of Medicine, Division of Infectious Diseases, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Vu L. Truong
- Aridis Pharmaceuticals Inc., Los Gatos, California, United States of America
| | - Richard A. Bowen
- Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Mark R. Walter
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | | | - James J. Kobie
- Department of Medicine, Division of Infectious Diseases, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
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Piepenbrink MS, Park JG, Desphande A, Loos A, Ye C, Basu M, Sarkar S, Chauvin D, Woo J, Lovalenti P, Erdmann NB, Goepfert PA, Truong VL, Bowen RA, Walter MR, Martinez-Sobrido L, Kobie JJ. Potent universal-coronavirus therapeutic activity mediated by direct respiratory administration of a Spike S2 domain-specific human neutralizing monoclonal antibody. bioRxiv 2022. [PMID: 35291292 DOI: 10.1101/2022.03.05.483133] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) marks the third novel β-coronavirus to cause significant human mortality in the last two decades. Although vaccines are available, too few have been administered worldwide to keep the virus in check and to prevent mutations leading to immune escape. To determine if antibodies could be identified with universal coronavirus activity, plasma from convalescent subjects was screened for IgG against a stabilized pre-fusion SARS-CoV-2 spike S2 domain, which is highly conserved between human β-coronavirus. From these subjects, several S2-specific human monoclonal antibodies (hmAbs) were developed that neutralized SARS-CoV-2 with recognition of all variants of concern (VoC) tested (Beta, Gamma, Delta, Epsilon, and Omicron). The hmAb 1249A8 emerged as the most potent and broad hmAb, able to recognize all human β-coronavirus and neutralize SARS-CoV and MERS-CoV. 1249A8 demonstrated significant prophylactic activity in K18 hACE2 mice infected with SARS-CoV-2 lineage A and lineage B Beta, and Omicron VoC. 1249A8 delivered as a single 4 mg/kg intranasal (i.n.) dose to hamsters 12 hours following infection with SARS-CoV-2 Delta protected them from weight loss, with therapeutic activity further enhanced when combined with 1213H7, an S1-specific neutralizing hmAb. As little as 2 mg/kg of 1249A8 i.n. dose 12 hours following infection with SARS-CoV Urbani strain, protected hamsters from weight loss and significantly reduced upper and lower respiratory viral burden. These results indicate in vivo cooperativity between S1 and S2 specific neutralizing hmAbs and that potent universal coronavirus neutralizing mAbs with therapeutic potential can be induced in humans and can guide universal coronavirus vaccine development.
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Piepenbrink MS, Park JG, Oladunni FS, Deshpande A, Basu M, Sarkar S, Loos A, Woo J, Lovalenti P, Sloan D, Ye C, Chiem K, Bates CW, Burch RE, Erdmann NB, Goepfert PA, Truong VL, Walter MR, Martinez-Sobrido L, Kobie JJ. Therapeutic activity of an inhaled potent SARS-CoV-2 neutralizing human monoclonal antibody in hamsters. Cell Rep Med 2021; 2:100218. [PMID: 33649747 PMCID: PMC7904445 DOI: 10.1016/j.xcrm.2021.100218] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 12/23/2020] [Accepted: 02/17/2021] [Indexed: 12/25/2022]
Abstract
SARS-CoV-2 infection results in viral burden in the respiratory tract, enabling transmission and leading to substantial lung pathology. The 1212C2 fully human monoclonal antibody was derived from an IgM memory B cell of a COVID-19 patient, has high affinity for the Spike protein receptor binding domain, neutralizes SARS-CoV-2, and exhibits in vivo prophylactic and therapeutic activity in hamsters when delivered intraperitoneally, reducing upper and lower respiratory viral burden and lung pathology. Inhalation of nebulized 1212C2 at levels as low as 0.6 mg/kg, corresponding to 0.03 mg/kg lung-deposited dose, reduced the viral burden below the detection limit and mitigated lung pathology. The therapeutic efficacy of an exceedingly low dose of inhaled 1212C2 supports the rationale for local lung delivery for dose-sparing benefits, as compared to the conventional parenteral route of administration. These results suggest that the clinical development of 1212C2 formulated and delivered via inhalation for the treatment of SARS-CoV-2 infection should be considered. The 1212C2 human monoclonal antibody potently neutralizes SARS-CoV-2 1212C2 mAb was isolated from an IgM memory B cell of a recovered COVID-19 patient Inhaled 1212C2 mAb is rapidly distributed in the lungs Inhaled 1212C2 mAb treatment reduces viral burden and lung pathology in hamsters
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Affiliation(s)
- Michael S Piepenbrink
- Department of Medicine, Division of Infectious Diseases, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Jun-Gyu Park
- Texas Biomedical Research Institute, San Antonio, TX, USA
| | | | - Ashlesha Deshpande
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Madhubanti Basu
- Department of Medicine, Division of Infectious Diseases, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Sanghita Sarkar
- Department of Medicine, Division of Infectious Diseases, University of Alabama at Birmingham, Birmingham, AL, USA
| | | | | | | | | | - Chengjin Ye
- Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Kevin Chiem
- Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Christopher W Bates
- Department of Medicine, Division of Infectious Diseases, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Reuben E Burch
- Department of Medicine, Division of Infectious Diseases, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Nathaniel B Erdmann
- Department of Medicine, Division of Infectious Diseases, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Paul A Goepfert
- Department of Medicine, Division of Infectious Diseases, University of Alabama at Birmingham, Birmingham, AL, USA.,Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA
| | | | - Mark R Walter
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA
| | | | - James J Kobie
- Department of Medicine, Division of Infectious Diseases, University of Alabama at Birmingham, Birmingham, AL, USA
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Loos A, Weich N, Woo J, Lalonde G, Yee L, Dummer W, Truong VL. 674. Pre-Clinical and Phase I Safety Data for Anti-Pseudomonas aeruginosa Human Monoclonal Antibody AR-105. Open Forum Infect Dis 2019. [PMCID: PMC6811070 DOI: 10.1093/ofid/ofz360.742] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Background Anti-bacterial monoclonal antibodies can serve as a new treatment modality for difficult to treat infections. AR-105 is a fully human IgG1 monoclonal antibody (mAb) that binds to an extracellular polysaccharide epitope of Pseudomonas aeruginosa (PA) and was shown to mediate in vitro complement-dependent opsonophagocytic killing. AR-105 is currently being tested in a global Phase 2 clinical trial as an adjunctive treatment to standard of care antibiotics in ventilator-associated pneumonia patients. Here we present pre-clinical efficacy and clinical safety data for AR-105. Methods Efficacy in nonclinical studies against PA pneumonia was tested in prophylactic and therapeutic mouse models, either as a stand-alone therapy or in combination with antibiotics. Mice were dosed intranasally or by intravenous infusion with AR-105 post or prior to infection with PA and survival or lung bacteriology were monitored. In a clinical Phase 1 open-label study, 16 healthy volunteers received 2, 8, or 20 mg/kg of AR-105. Adverse events, immunogenicity, and pharmacokinetic (PK) profiles were evaluated for up to 84 days following administration. Results In the animal models, AR-105 reduced lung bacterial counts in a dose-dependent manner, and improved survival (80% in the treated group vs. 0% in the control group). Combination of AR-105 with antibiotics was more effective than monotherapy. In the Phase I study, no serious adverse events (AE) were observed in any cohort. Few AE were deemed related to the investigational drug, and all were mild and transient. AR-105 was found to be well tolerated in healthy volunteers with no anti-drug antibodies (ADA) detected. The PK profile was comparable with other human IgG1 mAbs, exhibiting a serum half-life of approximately 20 days. Conclusion AR-105 was confirmed to be effective in PA pneumonia animal models, either as stand-alone therapeutic or in combination with antibiotics. In the Phase 1 clinical study, AR-105 was shown to be safe and well-tolerated, with a PK profile similar to that of other IgG1 mAbs. AR-105 is a promising drug candidate for therapy of PA pneumonia. ![]()
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Disclosures All authors: No reported disclosures.
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Affiliation(s)
| | | | | | - Guy Lalonde
- Aridis Pharmaceuticals, San Jose, California
| | - Luisa Yee
- Aridis Pharmaceuticals, San Jose, California
| | | | - Vu L Truong
- Aridis Pharmaceuticals, San Jose, California
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Abstract
Background Gallium nitrate citrate exhibits strong antibacterial activity and was recently shown to be safe and efficacious when intravenously administered to cystic fibrosis patients in a Phase 2 clinical study conducted by the University of Washington. We are developing an inhaled formulation of gallium citrate (AR-501), which is being tested in a Phase 1/2a clinical study. The in vitro antimicrobial activities, drug resistance profile, activities in combination with selected antibiotics, and in vivo animal efficacy if the inhaled vs. IV formulation is being presented. Methods MIC tests were performed on strains using the CLSI susceptibility test standards. Resistance testing exposed bacteria to 20 cycles at ranges above and below the MIC level of the drug used.SPF mice (C57BL/6J, 7–9 weeks) were inoculated intranasally with P. aeruginosa under ketamine/xylazine anesthesia. Inhalation of AR-501 used an Aeroneb Solo nebulizer. Gallium levels were determined by elemental analysis using atomic absorption spectroscopy. CFU levels were measured by enumeration of bacterial colonies following serial dilution of tissue homogenates. Results In vitro efficacy: MIC testing demonstrates the efficacy of AR-501 against gram (−), gram (+) and several species of mycobacteria of clinical isolates and the comparative antibacterial response with antibiotics. Resistance testing showed that AR-501 exhibited lower propensity to develop resistance than the antibiotics tested. In vivo efficacy: AR-501 Inhalation also increased the median survival time compared with IV dosing in the murine model. Bacterial clearance was increased when Tobramycin and AR-501 are co-administered. Comparative analysis of AR-501 after IH route demonstrate increased gallium levels in BAL and reduced levels in the kidney in contrast to IV route. Conclusion In vitro studies demonstrate the susceptibility of gram (−), gram (+) and mycobacteria pathogens and the dose range of AR-501 compared with SOC antibiotics. In vivo studies confirm the therapeutic efficacy of AR-501 in bacterial pneumonia by IH delivery and demonstrate that bacterial clearance is enhanced when SOC antibiotics are used in combination with AR-501. ![]()
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Disclosures All authors: No reported disclosures.
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Affiliation(s)
| | - Ken Hearne
- Aridis Pharmaceuticals, San Jose, California
| | - Andy Kelson
- Aridis Pharmaceuticals, San Jose, California
| | - Luisa Yee
- Aridis Pharmaceuticals, San Jose, California
| | | | - Vu L Truong
- Aridis Pharmaceuticals Ltd., San Jose, California
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Zeng Y, Fan H, Chiueh G, Pham B, Martin R, Lechuga-Ballesteros D, Truong VL, Joshi SB, Middaugh CR. Towards development of stable formulations of a live attenuated bacterial vaccine: A preformulation study facilitated by a biophysical approach. Human Vaccines 2014; 5:322-31. [DOI: 10.4161/hv.5.5.7559] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Abstract
5'-Nucleotidase I (N-I) from rabbit heart was purified to homogeneity. After ammonium sulfate precipitation, the purification involved chromatography on phosphocellulose, DEAE-Sepharose, AMP-agarose, and ADP-agarose. The pure enzyme has a specific activity of 318 mumol (mg of protein)-1 min-1. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate yields a subunit molecular weight of 40,000. N-I is activated by ADP but not by ATP, in contrast to the 5'-nucleotidase (N-II) purified by Itoh et al. (1986), which is activated by ATP and, less well, by ADP. N-I displays sigmoidal saturation kinetics in the absence of ADP and hyperbolic kinetics in the presence of ADP. Partially purified N-I was previously shown to prefer AMP over IMP as substrate (Truong et al., 1988); this has been confirmed for pure N-I. Comparison of AMP and ADP concentrations reported to occur in heart with the kinetic behavior of N-I implicates N-I as the enzyme responsible for producing adenosine under conditions leading to a rise in ADP and AMP, such as hypoxia or increased workload. N-I is not activated by the ADP analogue adenosine 5'-methylenediphosphonate (AOPCP) and is only weakly inhibited by relatively high concentrations of AOPCP, in contrast to 5'-nucleotidase from plasma membrane, which is powerfully inhibited by this analogue. N-I shows an absolute dependence on Mg2+ ions. Mn2+ and Co2+ ions can replace Mg2+ ions as activator; Ni2+ and Fe2+ are much less effective, while Ca2+, Ba2+, Zn2+, and Cu2+ fail to activate the enzyme.
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Affiliation(s)
- Y Yamazaki
- Graduate Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02254
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Abstract
Rabbit heart contains two soluble 5'-nucleotidases, termed N-I and N-II, which can be separated using phosphocellulose chromatography. N-I prefers AMP over IMP as substrate, in contrast to N-II which prefers IMP over AMP. Both enzymes require Mg2+, but the optimum Mg2+ concentrations for the two enzymes are different. High concentrations of NaCl inhibit N-I and activate N-II. Purified N-I is activated by ADP but not by ATP. According to Itoh et al. (1986), purified N-II is activated by both ADP and ATP. N-I has been purified approximately 1000-fold to a specific activity of approximately 100 mumol/mg protein/min. The properties of N-I suggest that it is the enzyme responsible for the release of adenosine from AMP under conditions of hypoxia or increased work load.
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Affiliation(s)
- Y Yamazaki
- Graduate Department of Biochemistry, Brandeis University Waltham, Massachusetts 02254
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Truong VL, Collinson AR, Lowenstein JM. 5'-Nucleotidases in rat heart. Evidence for the occurrence of two soluble enzymes with different substrate specificities. Biochem J 1988; 253:117-21. [PMID: 2844162 PMCID: PMC1149265 DOI: 10.1042/bj2530117] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Chromatography of soluble proteins from rat heart on phosphocellulose columns separates two 5'-nucleotidases. The first to emerge from the column shows a preference for AMP over IMP as substrate, whereas the second shows a preference for IMP over AMP. The properties of the IMP-preferring enzyme, including the conditions under which it is eluted from phosphocellulose columns, show it to be the enzyme studied by Itoh, Oka & Ozasa [Biochem. J. (1986) 235, 847-851]. The kinetic properties of the AMP-preferring enzyme indicate that it is likely to be the enzyme responsible for the production of adenosine under conditions of hypoxia and increased work load, and with metabolic stresses such as a high load of acetate.
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Affiliation(s)
- V L Truong
- Graduate Department of Biochemistry, Brandeis University, Waltham, MA 02254
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