Proteinase inhibitors in rat serum. Purification and partial characterization of three functionally distinct trypsin inhibitors

Abstract

Three different serine proteinase inhibitors were isolated from rat serum and purified to apparent homogeneity. One of the inhibitors appears to be homologous to a1-proteinase inhibitor isolated from man and other species, but the other two, designated rat proteinase inhibitor I and rat proteinase inhibitor II, seem to have no human counterpart. ac-Proteinase inhibitor (Mr 55000) inhibits trypsin, chymotrypsin and elastase, the three serine proteinases tested. Rat proteinase inhibitor I (M' 66000) is active towards trypsin and chymotrypsin, but is inactive towards elastase. Rat proteinase inhibitor II (M, 65000) is an effective inhibitor of trypsin only. Their contributions to the trypsin-inhibitory capacity of rat serum are about 68, 14 and 18% for a1-proteinase inhibitor, rat proteinase inhibitor I and rat proteinase inhibitor II respectively.

Purification and partial characterization of α1-proteinase inhibitor in the common marmoset (Callithrix jacchus)

“…Recently, α 1 -PI has also been described as being of importance in modulating immunity, inflammation, proteostasis, apoptosis, and possibly cellular senescence (Hunt and Tuder, 2012). Alpha 1 -proteinase inhibitor has been purified from many species including human (Pannell et al, 1974), dog (Melgarejo et al, 1996), cat (Fetz et al, 2004), sheep (Mistry et al, 1991), goat (Vankan and Bell, 1993), rabbit (Koj et al, 1978a), mouse (Minnich et al, 1984), rat (Kuehn et al, 1984), guinea pig (Suzuki et al, 1990), Rhesus monkey (Berninger and Mathis, 1976), and opossum (Catanese and Kress, 1993). Across species, the protein structure and function remain similar, however, a relative deficiency has been reported in people with certain genetic genotypes (Brebner and Stockley, 2013).…”

Isolation and characterization of sheep α1-proteinase inhibitor

“…In contrast, Sinha et al [6] used bovine trypsin, which is susceptible to inhibition by other plasma proteinase inhibitors such as a2-antiplasmin and antithrombin III, and alPI is not the most likely inhibitor [28]. Furthermore, mammalian sera, including human [29], goat [11], horse [30], rabbit [10], rat [7] and mouse [8], have been reported to contain more than one proteinase inhibitor in the z1-globulin fraction, which can be separated by PAGE. Of particular relevance to this work are the studies where two of these inhibitors have been partially characterized [7,8,29,31] and which differ in their Mr and their inhibitory capacities towards elastase and bovine trypsin.…”

“…Furthermore, mammalian sera, including human [29], goat [11], horse [30], rabbit [10], rat [7] and mouse [8], have been reported to contain more than one proteinase inhibitor in the z1-globulin fraction, which can be separated by PAGE. Of particular relevance to this work are the studies where two of these inhibitors have been partially characterized [7,8,29,31] and which differ in their Mr and their inhibitory capacities towards elastase and bovine trypsin. In each case the proteinase inhibitor with the lower Mr (53 000-58 000) behaved like human aclPI and inhibited both elastase (leucocyte or pancreatic) and bovine trypsin at a molar ratio of 1:1.…”

“…This is unlike human a.PI, which inhibits all three proteinases on a 1:1 molar basis. This result is questionable in the light of findings that a1PI from rat [7], mouse [8], dog [9], rabbit [10] and goat [11] are chemically and functionally similar to the human protein, although none of the preparations cross-reacts serologically with the human protein.…”

Purification and Characterization of Serine Proteinase Inhibitor from CarpCyprinus carpioOrdinary Muscle

“…11) Some properties of the Cil-proteinase inhibitor, for example, pH-stability,38) thermo-stability,39) isoelectric point,32.33) inhibitory spectrum, 35.36,40) and stability of E· I complex against denaturing and reducing reagents such as SDS and 2-mercaptoethanol,35 "'37,41) were very similar to those of our inhibitor. Recently, Kuehn et al 42 ) reported that rat serum contains a number of serine proteinase inhibitors such as Ci 1 -proteinase inhibitor and rat proteinase inhibitors I-I and I-II. Subsequently, they also found these serine proteinase inhibitors in rat skeletal muscle by immunological methods.…”