Isolation and amino-acid sequence of two inhibitors of serine proteinases, members of the squash inhibitor family, from Echinocystis lobata seeds.
Two serine proteinase inhibitors (ELTI I and ELTI II) have been isolated from mature seeds of Echinocystis lobata by ammonium sulfate fractionation, methanol precipitation, ion exchange chromatography, affinity chromatography on immobilized anhydrotrypsin and HPLC. ELTI I and ELTI II consist of 33 and 29 amino-acid residues, respectively. The primary structures of these inhibitors are as follows: ELTI I KEEQRVCPRILMRCKRDSDCLAQCTCQQSGFCG ELTI II RVCPRILMRCKRDSDCLAQCTCQQSGFCG The inhibitors show sequence similarity with the squash inhibitor family. ELTI I differs from ELTI II only by the presence of the NH2-terminal tetrapeptide Lys-Glu-Glu-Gln. The association constants (Ka) of ELTI I and ELTI II with bovine-trypsin were determined to be 6.6 x 10(10) M-1, and 3.1 x 10(11) M-1, whereas the association constants of these inhibitors with cathepsin G were 1.2 x 10(7) M-1, and 1.1 x 10(7) M-1, respectively.
Stachowiak
D
D
Institute of Biochemistry, University of Wrocław, Poland.
Polanowski
A
A
Bieniarz
G
G
Wilusz
T
T
D000595:Amino Acid Sequence; D002846:Chromatography, Affinity; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D008969:Molecular Sequence Data; D015842:Serine Proteinase Inhibitors / Q000737:chemistry / Q000302:isolation & purification*; D014675:Vegetables / Q000737:chemistry*
D015842:Serine Proteinase Inhibitors