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Disulfide linked αoLH-gelonin conjugate failed to recombine with βoLH subunit to generate bioeffective hormonotoxin

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Since, linking of ovine luteinizing hormone (oLH) to ribosome inactivating protein gelonin (in oLH-gelonin conjugate) occur via the alpha-subunit, αoLH, an attempt has been made to develop a ‘universal’ hormonotoxin for selective targeting to specific cells in the gonads. Four different molar ratios of oLH and N-succinimidyl-3-(2-pyridyldithio) propionate (SPDP) were used to activate the epsilon amino (ψ-NH2) groups of αoLH. The αoLH-SPDP derivatives recombine to native beta subunit of oLH (βoLH) and the purified recombinants retained substantial receptor binding, steroidogenic activity and immunoreactivity to native oLH. The disulfide linked αoLH-S-S-gelonin conjugates prepared by SPDP method were purified by gel filtration chromatography and analysed by reverse-phase high performance liquid chromatography (RP-HPLC). In order to obtain specificity and bioeffectivity, the αoLH-S-S-gelonin conjugates were allowed to recombine to native βoLH and the recombination mixture was further purified by gel-filtration chromatography. The RP-HPLC analysis of these recombinants indicated that αoLH-S-S-gelonin did not recombine to βoLH. The failure of recombination may be due to the reasons. (i) The site of ε-NH2 activation by SPDP may be different in the αoLH than the native oLH. (ii) The activation site may be in close proximity to the annealing site which facilitates the recombination of β-subunit but failured to reassociate to αoLH-S-S-gelonin conjugate. (iii) The introduction of gelonin (30 kDa basic protein) might have induced some steric hinderence for βoLH to recombine to the αoLH site which might have been masked in αoLH-S-S-gelonin conjugates. (Mol Cell Biochem120: 95–102, 1993)

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ovine Luteinizing Hormone


alpha subunit of oLH


beta subunit of oLH


Bovine Serum Albumin




Reverse Phase High Performance Liquid Chromatography


Thyroid Stimulating Hormone


Follicle Stimulating Hormone


Luteinizing Hormone


equine Chorionic Gonadotropin


Dulbecco's Modified Eagles Medium


4-(2-Hydroxyethyl)-1 Piperazine Ethane Sulfonic acid


Pokeweed Antiviral Protein




human Chorionic Gonadotropin


Thyrotropin Releasing Hormone


Corticotropin Releasing Factor


human Placental Lactogen


Trifluroacetic Acid


SPDP activated derivative of αoLH


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Correspondence to Vinod Singh.

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Singh, V., Curtiss, R. Disulfide linked αoLH-gelonin conjugate failed to recombine with βoLH subunit to generate bioeffective hormonotoxin. Mol Cell Biochem 120, 95–102 (1993). https://doi.org/10.1007/BF00926081

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Key Words

  • gonadotropin
  • immunoreactivity
  • receptor binding
  • steroidogenesis