title: A dimeric high-molecular-weight chymotrypsin inhibitor with antitumor and HIV-1 reverse transcriptase inhibitory activities from seeds of Acacia confusa.
abstract: A dimeric 70-kDa chymotrypsin inhibitor with substantial N-terminal sequence homology to serine protease inhibitors was isolated from Acacia confusa seeds. The chymotrypsin inhibitor was purified using a protocol that entailed ion exchange chromatography on Q-Sepharose, SP-Sepharose and fast protein liquid chromatography-gel filtration on Superdex 75. The chymotrypsin inhibitor was unadsorbed on both Q-Sepharose and SP-Sepharose. Its chymotrypsin inhibitory activity was stable from pH 3 to 10 and from 0 to 50 degrees C. It exerted antiproliferative activity toward breast cancer MCF-7 cells with an IC(50) of 10.7+/-4.2 microM. It inhibited HIV-1 reverse transcriptase with an IC(50) of 8+/-1.5 microM. It was devoid of antifungal activity toward a variety of fungal species. The distinctive features of the chymotrypsin inhibitor included dimeric nature, a high molecular mass, lack of trypsin inhibitory activity, highly potent HIV-1 reverse transcriptase inhibitory activity, specific antitumor activity and relatively high pH-stability.
authors: School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China. lamszekwan@yahoo.com.hk
authors: S K
authors: SK
authors: Lam
authors: T B
authors: TB
authors: Ng
mesh_terms: D000045:Acacia / Q000737:chemistry*; D000327:Adsorption; D000595:Amino Acid Sequence; D000972:Antineoplastic Agents, Phytogenic / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D001943:Breast Neoplasms / Q000188:drug therapy; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002845:Chromatography / Q000379:methods; D002918:Chymotrypsin / Q000037:antagonists & inhibitors*; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D005260:Female; D005658:Fungi / Q000187:drug effects; D054303:HIV Reverse Transcriptase / Q000037:antagonists & inhibitors*; D056945:Hep G2 Cells; D006801:Humans; D006863:Hydrogen-Ion Concentration; D020128:Inhibitory Concentration 50; D015394:Molecular Structure; D008517:Phytotherapy; D010940:Plant Proteins / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D018894:Reverse Transcriptase Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D012639:Seeds; D012685:Sepharose; D017385:Sequence Homology; D013696:Temperature
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D010940:Plant Proteins; D018894:Reverse Transcriptase Inhibitors; D012685:Sepharose; C514824:reverse transcriptase, Human immunodeficiency virus 1; D054303:HIV Reverse Transcriptase; D002918:Chymotrypsin