The trypsin-inhibitory, immunostimulatory and antiproliferative activities of a napin-like polypeptide from Chinese cabbage seeds.
A heterodimeric 13.8 kDa napin-like polypeptide has previously been isolated from Chinese cabbage (Brassica parachinensis) seeds with a procedure involving ion exchange chromatography on DEAE-cellulose, affinity chromatography on Affi-gel blue gel, FPLC-ion exchange chromatography on Mono S and FPLC-gel filtration on Superdex 75. In the present study the N-terminal sequence of the 8.8 kDa subunit of the polypeptide (PQGPQQRPPKLLQQQTNEEHE) was found to have pronounced homology to napins, albumins and trypsin inhibitors, but demonstrated little similarity to the 5 kDa subunit. The polypeptide stimulated nitrite production by mouse peritoneal macrophages and reduced the viability of leukaemia (L1210) cells. It inhibited trypsin with a higher potency than it inhibited chymotrypsin, but was devoid of ribonuclease and antifungal activities.
Department of Biochemistry, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China. biochemistry@cuhk.edu.hk
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Patrick H K
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D000595:Amino Acid Sequence; D000818:Animals; D001937:Brassica / Q000737:chemistry*; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D002918:Chymotrypsin / Q000037:antagonists & inhibitors / Q000378:metabolism; D007938:Leukemia / Q000473:pathology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects* / Q000276:immunology*; D051379:Mice; D008969:Molecular Sequence Data; D009566:Nitrates / Q000378:metabolism; D010455:Peptides / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D010940:Plant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D012639:Seeds / Q000737:chemistry*; D017386:Sequence Homology, Amino Acid; D014357:Trypsin / Q000378:metabolism; D014361:Trypsin Inhibitors / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*
D008070:Lipopolysaccharides; D009566:Nitrates; D010455:Peptides; D010940:Plant Proteins; D014361:Trypsin Inhibitors; D002918:Chymotrypsin; D014357:Trypsin