A saporin-insulin conjugate: synthesis and biochemical characterization.
Saporin, a single-chain, non-cytotoxic, ribosome-inactivating protein from Saponaria officinalis, was chemically linked to the hormone insulin in a 1:1 complex. To follow by dynamic video microscopy the endocytosis and intracellular transport in vivo, a second covalent conjugate with a saporin derivative labelled with fluorescein isothiocyanate was also prepared. Both conjugates were characterized with reference to homogeneity, stoichiometry, optical spectroscopy and toxicity. Both were found to exhibit scarce toxicity toward both CHO and HEP G2 cells; optical video microscopy on living cells indicates that reduced toxicity may be (partly) due to a very limited binding of the saporin-insulin conjugate to membrane receptors. These results suggest a strategy for new possible covalent conjugates of saporin with alternative and specific macromolecular carriers.
Dipartimento di Scienze Biochimiche e Centro di Biologia Molecolare del CNR, Università La Sapienza, Rome, Italy.
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Ippoliti
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Lendaro
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Bellelli
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Fiani
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Benedetti
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Evangelista
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Brunori
D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000302:isolation & purification* / Q000378:metabolism / Q000633:toxicity; D001665:Binding Sites; D016466:CHO Cells / Q000166:cytology / Q000187:drug effects*; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D006224:Cricetinae; D004591:Electrophoresis, Polyacrylamide Gel; D016650:Fluorescein-5-isothiocyanate / Q000737:chemistry / Q000378:metabolism; D000922:Immunotoxins / Q000302:isolation & purification / Q000378:metabolism / Q000633:toxicity; D007328:Insulin / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D009699:N-Glycosyl Hydrolases; D010940:Plant Proteins / Q000302:isolation & purification* / Q000378:metabolism; D011972:Receptor, Insulin / Q000378:metabolism; D054789:Ribosome Inactivating Proteins, Type 1; D000076985:Saporins
D000972:Antineoplastic Agents, Phytogenic; D000922:Immunotoxins; D007328:Insulin; D010940:Plant Proteins; D054789:Ribosome Inactivating Proteins, Type 1; D011972:Receptor, Insulin; D009699:N-Glycosyl Hydrolases; D000076985:Saporins; D016650:Fluorescein-5-isothiocyanate