Haim Moskowitz - Academia.edu (original) (raw)

Papers by Haim Moskowitz

Toxicon, 1995

Positive cooperativity among insecticidal scorpion neurotoxins. Toxicon 33, 1099-1102, 1995.--The... more Positive cooperativity among insecticidal scorpion neurotoxins. Toxicon 33, 1099-1102, 1995.--The insecticidal activity of scorpion neurotoxic polypeptides increased 5-10-fold with no apparent increase in mammalian toxicity when a combination of two toxins was injected. Synergistic combinations could be predicted from binding studies and competitive displacement assays. Our results indicate that simultaneous expression in baculovirus or other transgenic organisms of the synergistic combinations of insecticidal toxins may result in more potent insect-selective biopesticides.

European Journal of Biochemistry, 1998

The scorpion venom-derived excitatory and depressant insect-selective polypeptide neurotoxins mod... more The scorpion venom-derived excitatory and depressant insect-selective polypeptide neurotoxins modify sodium conductance in insect neuronal membranes and differ greatly in their primary structures and symptoms induced in blow fly larvae. We report here the purification and characterization of a new insect selective toxin, LqhIT5. LqhIT5 is more similar to the excitatory toxins in its mode of action and the depressant toxins in its primary structure. This toxin is a single polypeptide composed of 61 amino acids that are cross linked by four disulfide bonds. When LqhIT5 is injected into blow fly larvae, a fast contraction paralysis occurs without depressant activity. No mammalian toxicity was detected by subcutaneous or intracranial injections of this toxin into mice. Sequence comparison of LqhIT5 and known depressant toxins shows a high degree of similarity among the amino acids located on the C-terminus of the toxins. However, there are some clear differences in the amino acids located close to the N-terminus of the toxins. By the aid of homology modeling, we demonstrated that these amino acids have the same orientation in the tertiary structure of the molecule and are exposed to the environment. The change in the mode of action of LqhIT5 (no depressant activity) by substitutions of a few amino acids located on a specific exposed area of the toxin shed a new light on the structure/function relationship of scorpion toxins. These results caution that similarity in the mechanism of action of scorpion toxins does not always follow from an overall similarity in sequence.

Neuroscience Letters, 1991

Locust neuronal sodium channels were solubilized by 1% cholate and 0.2% Triton X-100, and their f... more Locust neuronal sodium channels were solubilized by 1% cholate and 0.2% Triton X-100, and their functionality was monitored by [~H]saxitoxin (STX) binding assays. About 40% of STX binding activity was recovered in the solubilized fraction without affecting affinity (Kd = 0.5 nM) and the time and temperature dependent STX binding activity was significantly stabilized in the presence of 20 nM STX. Partial purification by an anion exchange resin yielded a 20% recovery and a 3.5 times increase in the specific STX binding activity. Identification of the locust solubilized sodium channels by immunoprecipitation and radiophosphorylation revealed a Mr of 245,000 on SDS-PAGE. The present solubilized preparation will enable the study of the unique pharmacology of insect sodium channels.

Insect Biochemistry and Molecular Biology, 1994

Binding assays with the radioiodinated depressant (LqhlTz) and excitatory (AalT) insect selective... more Binding assays with the radioiodinated depressant (LqhlTz) and excitatory (AalT) insect selective neurotoxins derived from scorpion venoms to neuronal membrane preparations derived from cockroach, fly and lepidopterous larvae coupled with the employment of sodium channel site-directed antibodies resulted in the following information. (1) The two toxins were shown to bind with high affinity to the insect neuronal preparations and revealed similar binding constants in each of the various preparations.

Biochimica et Biophysica Acta (BBA) - Biomembranes, 1990

Archives of Insect Biochemistry and Physiology, 1993

Modern Agriculture and the Environment, 1997

Translational Oncology, 2013

Poor drug delivery and penetration of antibody-mediated therapies pose significant obstacles to e... more Poor drug delivery and penetration of antibody-mediated therapies pose significant obstacles to effective treatment of solid tumors. This study explored the role of pharmacokinetics, valency, and molecular weight in maximizing drug delivery. Biodistribution of a fibroblast growth factor receptor 4 (FGFR4) targeting CovX-body (an FGFR4-binding peptide covalently linked to a nontargeting IgG scaffold; 150 kDa) and enzymatically generated FGFR4 targeting F(ab)2 (100 kDa) and Fab (50 kDa) fragments was measured. Peak tumor levels were achieved in 1 to 2 hours for Fab and F(ab)2 versus 8 hours for IgG, and the percentage injected dose in tumors was 0.45%, 0.5%, and 2.5%, respectively, compared to 0.3%, 2%, and 6% of their nontargeting controls. To explore the contribution of multivalent binding, homodimeric peptides were conjugated to the different sized scaffolds, creating FGFR4 targeting IgG and F(ab)2 with four peptides and Fab with two peptides. Increased valency resulted in an increase in cell surface binding of the bivalent constructs. There was an inverse relationship between valency and intratumoral drug concentration, consistent with targeted consumption. Immunohistochemical analysis demonstrated increased size and increased cell binding decreased tumor penetration. The binding site barrier hypothesis suggests that limited tumor penetration, as a result of high-affinity binding, could result in decreased efficacy. In our studies, increased target binding translated into superior efficacy of the IgG instead, because of superior inhibition of FGFR4 proliferation pathways and dosing through the binding site barrier. Increasing valency is therefore an effective way to increase the efficacy of antibody-based drugs.

Toxicon, 1995

Eleventh World Congress 269 reinvestigated the possibility that the sea anemone toxins of these t... more Eleventh World Congress 269 reinvestigated the possibility that the sea anemone toxins of these two types interact with separate sites on the sodium channel, using Stichodactyla helianthus neurotoxin I (crustacean active) and Heteractis macrodactylus toxin llI (mammalian active) as examples of types 2 toxins. Both rat brain and crab walking leg axolemmal membranes were used for these experiments. Sh I bound to crab membranes with a K i of about 20 nM, but to the rat brain membranes with a K. > 10/zM. HmIII binding to crab nerve membranes was about the same as

European Journal of Biochemistry, 1997

An insect-selective scorpion toxin (AaIT5) was purified from the venom of the North African scorp... more An insect-selective scorpion toxin (AaIT5) was purified from the venom of the North African scorpion Androctonus australis, and its amino acid sequence was determined by a combination of automated Edman degradation, electrospray-ionization mass spectrometry, and sequence alignment. This insect toxin is very potent against the tobacco budworm, Heliothis virescens (100% lethal dose < 1.8 yg/100 mg body mass) and shows a distinct insect specificity and various symptoms. It is not toxic to mice after subcutaneous injection. The molecular mass of this toxin is 6882Da and the amino acid sequence is similar to those of Androctonus australis anti-insect toxin 4 (AaIT4), Leiurus quinquestriatus depressant anti-insect toxins (LqhIT2, LqqIT2), and Buthotus judaicus depressant anti-insect toxin (BjIT2).

Proceedings of the National Academy of Sciences, 2005

HIV type 1 (HIV-1) was shown to assemble either at the plasma membrane or in the membrane of late... more HIV type 1 (HIV-1) was shown to assemble either at the plasma membrane or in the membrane of late endosomes. Now, we report an essential role for human ubiquitin ligase POSH (Plenty of SH3s; hPOSH), a trans-Golgi network-associated protein, in the targeting of HIV-1 to the plasma membrane. Small inhibitory RNA-mediated silencing of hPOSH ablates virus secretion and Gag plasma membrane localization.

Insect Biochemistry and Molecular Biology, 2000

Juvenile hormone esterase (JHE) plays an essential role in insect development. It is partially re... more Juvenile hormone esterase (JHE) plays an essential role in insect development. It is partially responsible for the clearance of juvenile hormone (JH) which regulates various aspects of insect development and reproduction. Because of its role in regulating JH titer, this enzyme has been targeted for development of biologically-based insecticides. JHE was partially purified from the beetle, Tenebrio molitor, using a transition state analog as the affinity ligand. Two forms of JHE were characterized by activity analysis, isoelectric focusing, two-dimensional SDS-PAGE and N-terminal sequence analysis. The esterase is associated with two proteins of sizes 71 and 150 kDa, both of which are active on JH III. A partial cDNA clone for the enzyme was isolated based on the sequence of N-terminal and internal peptides. Its sequence indicates that JHE from T. molitor and Heliothis virescens may have a common origin.

Toxicon, 1995

Positive cooperativity among insecticidal scorpion neurotoxins. Toxicon 33, 1099-1102, 1995.--The... more Positive cooperativity among insecticidal scorpion neurotoxins. Toxicon 33, 1099-1102, 1995.--The insecticidal activity of scorpion neurotoxic polypeptides increased 5-10-fold with no apparent increase in mammalian toxicity when a combination of two toxins was injected. Synergistic combinations could be predicted from binding studies and competitive displacement assays. Our results indicate that simultaneous expression in baculovirus or other transgenic organisms of the synergistic combinations of insecticidal toxins may result in more potent insect-selective biopesticides.

European Journal of Biochemistry, 1998

The scorpion venom-derived excitatory and depressant insect-selective polypeptide neurotoxins mod... more The scorpion venom-derived excitatory and depressant insect-selective polypeptide neurotoxins modify sodium conductance in insect neuronal membranes and differ greatly in their primary structures and symptoms induced in blow fly larvae. We report here the purification and characterization of a new insect selective toxin, LqhIT5. LqhIT5 is more similar to the excitatory toxins in its mode of action and the depressant toxins in its primary structure. This toxin is a single polypeptide composed of 61 amino acids that are cross linked by four disulfide bonds. When LqhIT5 is injected into blow fly larvae, a fast contraction paralysis occurs without depressant activity. No mammalian toxicity was detected by subcutaneous or intracranial injections of this toxin into mice. Sequence comparison of LqhIT5 and known depressant toxins shows a high degree of similarity among the amino acids located on the C-terminus of the toxins. However, there are some clear differences in the amino acids located close to the N-terminus of the toxins. By the aid of homology modeling, we demonstrated that these amino acids have the same orientation in the tertiary structure of the molecule and are exposed to the environment. The change in the mode of action of LqhIT5 (no depressant activity) by substitutions of a few amino acids located on a specific exposed area of the toxin shed a new light on the structure/function relationship of scorpion toxins. These results caution that similarity in the mechanism of action of scorpion toxins does not always follow from an overall similarity in sequence.

Neuroscience Letters, 1991

Locust neuronal sodium channels were solubilized by 1% cholate and 0.2% Triton X-100, and their f... more Locust neuronal sodium channels were solubilized by 1% cholate and 0.2% Triton X-100, and their functionality was monitored by [~H]saxitoxin (STX) binding assays. About 40% of STX binding activity was recovered in the solubilized fraction without affecting affinity (Kd = 0.5 nM) and the time and temperature dependent STX binding activity was significantly stabilized in the presence of 20 nM STX. Partial purification by an anion exchange resin yielded a 20% recovery and a 3.5 times increase in the specific STX binding activity. Identification of the locust solubilized sodium channels by immunoprecipitation and radiophosphorylation revealed a Mr of 245,000 on SDS-PAGE. The present solubilized preparation will enable the study of the unique pharmacology of insect sodium channels.

Insect Biochemistry and Molecular Biology, 1994

Binding assays with the radioiodinated depressant (LqhlTz) and excitatory (AalT) insect selective... more Binding assays with the radioiodinated depressant (LqhlTz) and excitatory (AalT) insect selective neurotoxins derived from scorpion venoms to neuronal membrane preparations derived from cockroach, fly and lepidopterous larvae coupled with the employment of sodium channel site-directed antibodies resulted in the following information. (1) The two toxins were shown to bind with high affinity to the insect neuronal preparations and revealed similar binding constants in each of the various preparations.

Biochimica et Biophysica Acta (BBA) - Biomembranes, 1990

Archives of Insect Biochemistry and Physiology, 1993

Modern Agriculture and the Environment, 1997

Translational Oncology, 2013

Poor drug delivery and penetration of antibody-mediated therapies pose significant obstacles to e... more Poor drug delivery and penetration of antibody-mediated therapies pose significant obstacles to effective treatment of solid tumors. This study explored the role of pharmacokinetics, valency, and molecular weight in maximizing drug delivery. Biodistribution of a fibroblast growth factor receptor 4 (FGFR4) targeting CovX-body (an FGFR4-binding peptide covalently linked to a nontargeting IgG scaffold; 150 kDa) and enzymatically generated FGFR4 targeting F(ab)2 (100 kDa) and Fab (50 kDa) fragments was measured. Peak tumor levels were achieved in 1 to 2 hours for Fab and F(ab)2 versus 8 hours for IgG, and the percentage injected dose in tumors was 0.45%, 0.5%, and 2.5%, respectively, compared to 0.3%, 2%, and 6% of their nontargeting controls. To explore the contribution of multivalent binding, homodimeric peptides were conjugated to the different sized scaffolds, creating FGFR4 targeting IgG and F(ab)2 with four peptides and Fab with two peptides. Increased valency resulted in an increase in cell surface binding of the bivalent constructs. There was an inverse relationship between valency and intratumoral drug concentration, consistent with targeted consumption. Immunohistochemical analysis demonstrated increased size and increased cell binding decreased tumor penetration. The binding site barrier hypothesis suggests that limited tumor penetration, as a result of high-affinity binding, could result in decreased efficacy. In our studies, increased target binding translated into superior efficacy of the IgG instead, because of superior inhibition of FGFR4 proliferation pathways and dosing through the binding site barrier. Increasing valency is therefore an effective way to increase the efficacy of antibody-based drugs.

Toxicon, 1995

Eleventh World Congress 269 reinvestigated the possibility that the sea anemone toxins of these t... more Eleventh World Congress 269 reinvestigated the possibility that the sea anemone toxins of these two types interact with separate sites on the sodium channel, using Stichodactyla helianthus neurotoxin I (crustacean active) and Heteractis macrodactylus toxin llI (mammalian active) as examples of types 2 toxins. Both rat brain and crab walking leg axolemmal membranes were used for these experiments. Sh I bound to crab membranes with a K i of about 20 nM, but to the rat brain membranes with a K. > 10/zM. HmIII binding to crab nerve membranes was about the same as

European Journal of Biochemistry, 1997

An insect-selective scorpion toxin (AaIT5) was purified from the venom of the North African scorp... more An insect-selective scorpion toxin (AaIT5) was purified from the venom of the North African scorpion Androctonus australis, and its amino acid sequence was determined by a combination of automated Edman degradation, electrospray-ionization mass spectrometry, and sequence alignment. This insect toxin is very potent against the tobacco budworm, Heliothis virescens (100% lethal dose < 1.8 yg/100 mg body mass) and shows a distinct insect specificity and various symptoms. It is not toxic to mice after subcutaneous injection. The molecular mass of this toxin is 6882Da and the amino acid sequence is similar to those of Androctonus australis anti-insect toxin 4 (AaIT4), Leiurus quinquestriatus depressant anti-insect toxins (LqhIT2, LqqIT2), and Buthotus judaicus depressant anti-insect toxin (BjIT2).

Proceedings of the National Academy of Sciences, 2005

HIV type 1 (HIV-1) was shown to assemble either at the plasma membrane or in the membrane of late... more HIV type 1 (HIV-1) was shown to assemble either at the plasma membrane or in the membrane of late endosomes. Now, we report an essential role for human ubiquitin ligase POSH (Plenty of SH3s; hPOSH), a trans-Golgi network-associated protein, in the targeting of HIV-1 to the plasma membrane. Small inhibitory RNA-mediated silencing of hPOSH ablates virus secretion and Gag plasma membrane localization.

Insect Biochemistry and Molecular Biology, 2000

Juvenile hormone esterase (JHE) plays an essential role in insect development. It is partially re... more Juvenile hormone esterase (JHE) plays an essential role in insect development. It is partially responsible for the clearance of juvenile hormone (JH) which regulates various aspects of insect development and reproduction. Because of its role in regulating JH titer, this enzyme has been targeted for development of biologically-based insecticides. JHE was partially purified from the beetle, Tenebrio molitor, using a transition state analog as the affinity ligand. Two forms of JHE were characterized by activity analysis, isoelectric focusing, two-dimensional SDS-PAGE and N-terminal sequence analysis. The esterase is associated with two proteins of sizes 71 and 150 kDa, both of which are active on JH III. A partial cDNA clone for the enzyme was isolated based on the sequence of N-terminal and internal peptides. Its sequence indicates that JHE from T. molitor and Heliothis virescens may have a common origin.