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.
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Department of Biochemistry, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China. biochemistry@cuhk.edu.hk
Ngai
Patrick H K
PH
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