Author/Editor		Turk, B; Križaj, I; Kralj, B; Dolenc, I; Popovič, T; Bieth, JG; Turk, V
Title		Bovine stefin C, a new member of the stefin family
Type		članek
Source		J Biol Chem
Vol. and No.		Letnik 268, št. 10
Publication year		1993
Volume		str. 7323-9
Language		eng
Abstract		Four low Mr cysteine proteinase inhibitors with differnet pI values were isolated from bovine thymus using alkaline activation of the gland homogenate, affinity chromatography on a DEAE-cellulose column and a fast protein liquid chromatography Mono Q column, and hydrophobic chromatography on TSK Phenyl-5 PW column. One of the inhibitors was identified both as the monomeric and dimeric forms of stefin B. Two others, called cysteine proteinase inhibitor-1 and cysteine protoeinase inhibitor-2, were N terminally blocked and most likely belong to the stefin family. The complete amino acid sequence of the last inhibitor, namely bovine stefin C, was determined. The inhibitor consisted of 101 amino acids and its Mr was calculated to be 11,546. It exhibits considerable sequnece homology with other inhibitors from the stefin family. It was identified as the first tryptophane-containing stefin and it had a prolonged N terminus. The four inhibitors had similar inhibitory activities on cysteine proteinases. They were fast-acting inhibitors of papain and cathepsin L (k.ass more th. to equal 1.8 X 10č6 M-1 s-1) and formed very tight complexes with the enzymes (Ki less th. to equal 180 pM). In contrast, they were relatively poor inhibitors of cathepsin B (Ki more th. 100 nM).
Descriptors		CYSTEINE PROTEINASE INHIBITORS AMINO ACID SEQUENCE CYSTEINE PROTEINASES CATTLE THYMUS GLAND CHROMATOGRAPHY, AFFINITY CHROMATOGRAPHY, DEAE-CELLULOSE CHROMATOGRAPHY, HIGH PRESSURE LIQUID CHROMATOGRAPHY, GEL