ABSTRACT
alpha-Sarcin is a cytotoxic polypeptide produced by Aspergillus giganteus. It suppresses protein synthesis in yeast and wheat germ extracts and has a purine-specific RNase activity. The substance has been tested for its antitumor properties in a series of induced tumor systems in mice such as sarcoma and carcinoma among others. Although some of the in vitro effects of alpha-Sarcin on certain cellular components have been elucidated, the biological effects leading to cellular damage are still obscure. In this work we analysed the morphological changes in tumor cells derived from human pulmonary adenocarcinoma heterotransplanted and grown in naked mice, induced shortly (24 hours) after a single intratumoral injection of alpha-Sarcin (0.4 mg/tumor). The results obtained were: 1) swelling of mitochondria; 2) cell necrosis with partial removal of necrotic cells by phagocytosis; 3) thickening of interlobular connective tissue; 4) hyperplasia of goblet-cell-like clear cells. The mode of action concerning these cellular changes is presently uncertain. In view of the severity of these structural alterations it seems conceivable that alpha-Sarcin may enter the cell undergoing interactions with different intracellular structures. This would require a selective membrane permeabilization, perhaps induced upon formation of complexes with negatively-charged membrane phospholipids.
Subject(s)
Adenocarcinoma/ultrastructure , Antineoplastic Agents/pharmacology , Endoribonucleases , Fungal Proteins/pharmacology , Lung Neoplasms/ultrastructure , Protein Synthesis Inhibitors/pharmacology , Animals , Drug Screening Assays, Antitumor , Humans , Hyperplasia/chemically induced , Mice , Mice, Nude , Mitochondrial Swelling , Necrosis/chemically induced , PhagocytosisABSTRACT
Chromatographically pure toxin was isolated from the zooanthid Palythoa caribaeorum. Toxin isolation was achieved by extraction with 50% ethanol from the homogenized specimens, gel filtration on Sephadex G-50 and ion exchange chromatography on QAE- and SP-Sephadex. Final purification was obtained by gel filtration on Biogel P-6. The LD50 tested on the shore crab Carcinus maenas was 62.5 ng/kg.
Subject(s)
Acrylamides , Cnidaria/analysis , Cnidarian Venoms/isolation & purification , Animals , Chromatography, Gel , Chromatography, Ion Exchange , Cnidarian Venoms/toxicityABSTRACT
Two new bifunctional reagents suited for the step-wise cross-linking of cysteine and lysine residues in proteins are described. Application to lactate dehydrogenase yields a cross-link between cysteine-165 and lysine-179, which suggests an alternative mechanism by which the "essential" cysteine reacts. For the mapping of the environment of a known and well defined amino acid the use of semireversible bifunctional reagents is suggested.
