HMW and LMW kininogens

Modification of Sheep Plasma Kininogen by Free Radicals

Riboflavin sensitized photodynamic modifications of high molecular weight Kininogen (HMWK) isolated from sheep (Avis-arias) plasma leads to inactivation of antiproteinase activity and formation of aggregated products. A continued disappearance of the inhibitory activity towards papain and formation of high molecular weight adducts was observed with increasing concentration of riboflavin and varying time periods of incubation reaching a maximum value of over 85% (loss in activity). Aggregates resisted dissociation upon heating at 100 degrees C in 1% SDS. Aggregation and photoinactivation of HMWK was promoted by the substitution of H2O for deuterium oxide (D2O), which is known to prolong the life span of singlet oxygen, and suppressed by sodium azide a known singlet oxygen quencher. Mannitol and thiourea (hydroxyl radical scavenger) did not protect the antiproteinase activity of HMWK. Treatment with reducing agent resulted in decrease of the aggregated products suggesting the possible involvement of disulfide linkages in protein crosslinking. Tryptophan fluorescence was completely lost and significant production of dityrosine was detected in photoinactivated HMWK aggregates. Changes in the far Ultra violet circular dichroism (u.v.c.d.) spectrum of HMWK was indicative of loss of secondary structure. Analysis of modifications induced in HMWK by riboflavin reveals that the processes proceed via a singlet oxygen mediated pathway. It is concluded that the susceptibility of HMWK to oxidation may arise from oxidative modifications by reactive oxygen species generated in plasma.

The Fragments of Bovine High Molecular Weight Kininogen Promote Osteoblast Proliferation In Vitro

High molecular weight (HMW) kininogen is known to be a large plasma protein and cleaved by plasma proteinase kallikrein, then it generates four fragments in the blood coagulation cascade: heavy chain, bradykinin, fragment 1.2, and light chain. The fragment 1.2 has also been found in the basic protein fraction of bovine milk as a bioactive protein which promotes osteoblast proliferation. The milk basic protein has been shown to be a multi functional edible protein which promotes bone formation and inhibits bone resorption. In the present study, we purified the fragment 1.2 from bovine plasma and assessed it could promote osteoblast proliferation and posses the activity after pepsin digestion. Purified plasma HMW kininogen did not promote the proliferation, however, the kallikrein-cleaved HMW kininogen promoted the proliferation. The fragment 1.2, purified from the proteolysate, also promoted the proliferation. The pepsin digestion was performed according to the method of the assessment of allergenesity of genetically modified crops. After pepsin digestion, the fragment 1.2 generated resistant fragments and showed the promoting activity of osteoblast proliferation. These results suggest that the enzymatically-digested fragments of bovine HMW kininogen are able to be a naturally occurred active protein that promotes the bone formation by oral administration.

Isolation, characterization and kinetics of goat cystatins

Two cysteine proteinase inhibitors I and II were purified from goat kidney using alkaline denaturation, ammonium sulphate fractionation, gel filtration on Sephadex G-75 and ion exchange chromatography on DEAE cellulose. The purified inhibitors were homogenous and showed a single band on SDS PAGE under reducing and non-reducing conditions with an apparent molecular mass of 67 kDa. The cystatin forms were stable in the range of pH 3-10 and up to 95 degrees C. Immunological identity with the sheep LMW kininogen was obtained suggesting that the inhibitor is closely related to kininogens. Spectral studies confirm that the inhibitors have predominantly an alpha-helical structure and undergo major conformational changes during complex formation with papain. The inhibitors had similar inhibitory activities on cysteine proteinases. Both inhibitors inhibited papain, ficin and bromelain competitively, with maximum affinity for papain. The overall lower affinity of these inhibitors to cysteine proteinases compared to other known cystatins can be attributed to the unusual N-terminal sequence where Leu is substituted by Ile. Furthermore, N-terminal sequence analysis revealed maximum homology to mammalian LMW kininogen.

Purification and Characterization of Kininogens from Sheep Plasma

High molecular weight kininogen (HMWK) and low molecular weight kininogen (LMWK) have been purified from sheep (Avis Arias) plasma in three steps involving ammonium sulphate precipitation, column chromatography on Sephacryl-300HR and ion exchange chromatography on DEAE cellulose. HMWK gave a single band on native and SDS-PAGE with a molecular weight corresponding to 280 kDa. Under reducing conditions purified HMWK was again resolved to a single band with molecular weight corresponding to 140 kDa indicative of its dimeric nature. LMWK was resolved into two isoforms named as LMWK1 and LMWK2, with an apparent molecular weight of 68 kDa. The yield of HMWK, LMWK1 and 2 was about 8.1, 5.63 and 10.65 respectively. HMWK, LMWK1 and 2 strongly inhibited activities of ficin and papain but not of trypsin, chymotrypsin and bromelain. Ki values estimated for HMWK with papain and ficin was 0.8 and 0.6 nM respectively. Ki values estimated for LMWK1 and 2 with papain were 2.40 and 2.00 nM respectively. Binding of HMWK, LMWK1 and 2 to activated papain were accompanied by pronounced changes in secondary and tertiary structure that are compatible with perturbations of environment of aromatic residues.

Domain structure of bi-functional selenoprotein P

Human selenoprotein P (SeP), a selenium-rich plasma glycoprotein, is presumed to contain ten selenocysteine residues; one of which is located at the 40th residue in the N-terminal region and the remaining nine localized in the C-terminal third part. We have shown that SeP not only catalyses the reduction of phosphatidylcholine hydroperoxide by glutathione [Saito, Hayashi, Tanaka, Watanabe, Suzuki, Saito and Takahashi (1999) J. Biol. Chem. 274, 2866-2871], but also supplies its selenium to proliferating cells [Saito and Takahashi (2002) Eur. J. Biochem. 269, 5746-5751]. Treatment of SeP with plasma kallikrein resulted in a sequential limited proteolysis (Arg-235-Gln-236 and Arg-242-Asp-243). The N-terminal (residues 1-235) and C-terminal (residues 243-361) fragments exhibited enzyme activity and selenium-supply activity respectively. These results confirm that SeP is a bi-functional protein and suggest that the first selenocysteine residue is the active site of the enzyme and the remaining nine residues function as a selenium supplier.

Bovine milk kininogen fragment 1.2 promotes the proliferation of osteoblastic MC3T3-E1 cells

The active component on the proliferation of osteoblastic MC3T3-E1 cells was purified and identified from bovine milk. The growth-promoting activity was measured by [(3)H]thymidine incorporation on the cell. The purified protein showed a molecular size of 17 kDa on SDS-PAGE. Its amino-terminal amino acid sequence was very similar to the internal sequence of bovine high molecular weight (HMW) kininogen, which comprises fragment 1.2. The promotion of proliferation was specific for osteoblastic MC3T3-E1 cells, not for fibroblast BALB/3T3 cells. In blood coagulation, HMW kininogen is considered to be cleaved by a specific enzyme kallikrein. HMW kininogen then releases two peptides, a biologically active peptide bradykinin and fragment 1.2, but the fate of fragment 1.2 is unknown. This milk-derived protein that comprises to fragment 1.2 showed a growth-promoting activity of osteoblasts. We propose the possibility that milk plays an important role in bone formation by supplying the active agent for osteoblasts as well as supplying calcium.

Comparison of human and porcine tissue kallikrein substrate specificities

Little is known about the species specificity of tissue kallikrein-kininogen interaction since the kinetic parameters for Lys-bradykinin release from kininogen by tissue kallikreins from different animal species have not been reported. We have now determined the kinetic parameters for hydrolysis by human and porcine tissue kallikrein, hK1 and pK1, respectively (Berg et al., 1992) of two series of intramolecularly quenched fluorogenic peptides having the sequences that flank the scissile Arg-Ser or Met-Lys bond in human and bovine kininogen. Results have shown that peptides having sequences from human kininogen are better substrates for hK1 and peptides derived from bovine kininogen are better substrates for pK1. Kinetic data for hydrolysis of the Arg-Ser bond showed that differences in the interaction of residue(s) in positions P2'-P10' contribute to the efficiency of the cleavage and may be responsible for differences in their susceptibilities to the two kallikreins. Significant variations in the kinetic data were observed for the hydrolysis of the Met-Lys bond in substrates with an N-terminal extension at sites P3-P9. The highest k(cat)/Km value in the hydrolysis of Abz-[Gln370-Gln381]-bkng-EDDnp by pk1 demonstrates an important interaction of subsites S5-S4 with Gln and Thr residues in the bovine kininogen segment. A Gln370-Gln391 bovine kininogen fragment used to study the cleavage of both Met-Lys and Arg-Ser bonds in the same molecule confirmed the importance of an extended interaction site for species specificity among tissue kallikreins.

Canine plasma kininogen: evidence for the presence of two kininogens and purification of high molecular weight kininogen and characterization as multi-functional molecule

The ratio of kininogen that is substrate of plasma kallikrein to kininogen, which is not substrate of plasma kallikrein in canine plasma, was about 1:3.6 by differential assay of kininogens. When the plasma was gel-filtered through a column of Sephacryl S-300 superfine, two fractions, which released kinin by trypsin, were obtained. These results indicate that two kininogens with different molecular weights are present in the plasma and they show different susceptibility to plasma kallikrein. One kininogen was purified by ion-exchange and zinc-chelating affinity chromatographies. Purified kininogen showed a single band in sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing condition and its molecular weight was 125 kDa. Released kinin from the kininogen by trypsin was bradykinin. The kininogen inhibited papain and ficin but did not inhibit bromelain at the concentration used. The kininogen bound to carboxymethylated-papain and this binding was dissociated by 3M NaSCN. Canine plasma shortened the abnormal clotting time of human high molecular weight kininogen-deficint plasma. The kininogen also shortened the abnormal clotting time of the plasma. From these results, the purified kininogen was high molecular weight kininogen and it was multi-functional protein.

The role of vascular permeability factor and basic fibroblast growth factor in tumor angiogenesis

In the last decade a considerable amount of research has been dedicated to studying the process of angiogenesis. In the field of tumor biology angiogenesis is a relevant subject of investigation as well, since newly formed blood vessels are required for the growth of tumors and provide an exit route for metastasizing tumor cells. In this review we discuss some aspects of tumor angiogenesis with emphasis on the role that growth factors bFGF and VPF play in this process. A number of biochemical characteristics and biological properties of the two factors and their receptors are reviewed, and the expression of bFGF and VPF in both normal tissues and in tumors is discussed. Finally, we speculate on the use of bFGF and VPF expression as a diagnostic parameter and on possible clinical applications.

Dextran sulphate activation of the contact system in plasma and ascites

We have previously reported on the presence of proenzymes and inhibitors of the contact system in ascitic fluid. Malignancy-related ascites was also found to contain both high and low molecular weight kininogen (HK and LK). On this basis we have studied a possible activation of the contact system in ascites. Generation of amidolytic activity towards the chromogenic substrate S-2302 after incubation with dextran sulphate (DXS), was found in ascites from patients with gastrointestinal cancer, but not in ascites from patients with benign liver disease. It is concluded that malignancy-related ascites allows contact activation to take place, while benign ascites does not. This activation process, generating bradykinin, could possibly be of relevance to the mechanism of ascites generation. Plasma samples from patients with ascites were also tested in relation to activation of the contact system. Activation was evaluated by immunoblotting, studying the disappearance of intact HK after the initiation of activation with different concentrations of DXS. In control plasma, activation took place at low concentrations of DXS (25 - 50 micrograms/ml). In plasma samples from patients with malignancy-related or benign ascites, contact activation was depressed. In some samples concentrations of DXS up to 1 mg/ml, were not able to activate the contact system at all. Concentrations of proenzymes and relevant inhibitors in the contact system, HK and total protein were also determined. We found the concentration of prekallikrein to be positively correlated with the degree of activation. Concentrations of inhibitors such as C1-inhibitor, did not show any correlation with activation.

Purification and characterization of a novel substrate for plasma kallikrein (PK-120) in human plasma

A 120 kDa plasma protein, which is susceptible to plasma kallikrein, was purified from human plasma by polyethylene glycol fractionation followed by ion exchange chromatography using Q-Sepharose, S-Sepharose, and hydroxyapatite and gel filtration on Sephacryl S-200. The 120 kDa protein, termed PK-120 in this paper, was a single polypeptide chain containing about 20% sugar by weight and its concentration in plasma was estimated to be 80 micrograms/ml by ELISA. At least three fragments, 100, 70, and 35 kDa, were produced from PK-120 by plasma kallikrein. The N-terminal sequence and Western blot demonstrated that PK-120 was first cleaved to yield the 100 and 35 kDa fragments, then the 100 kDa fragment was cleaved into the 70 kDa fragment. N-Terminal sequence analyses of PK-120 and its fragments demonstrated that it is a novel plasma protein, distinct from high molecular weight kininogen, a natural substrate for plasma kallikrein.

An ultrasensitive chemiluminoenzyme immunoassay for the quantification of human tissue kininogens: application to synovial membrane and cartilage

A sandwich enzyme immunoassay using a chemiluminescent detection has been developed for the quantification of total human (high and low molecular weight) kininogens in tissue extracts. This assay uses monospecific polyclonal IgG labelled with alkaline phosphatase and the commercially available dioxetane derivatives as substrates, for the detection of immune complexes. This method exhibits a sensitivity level of 1 fmol/ml and allows a precise quantification of total kininogens in synovium and cartilage extracts. When characterized by Western blot, the immunoreactive material reveals the presence of both high and low molecular weight kininogens.

Cloning, expression and characterization of human kininogen domain 3

The internal domain 3 of the heavy chain of human kininogen, a cysteine proteinase inhibitor, was amplified by a polymerase chain reaction from the kininogen cDNA clone phKG36. The DNA fragment was expressed in Escherichia coli using the ompA expression vector pASK40 and the resulting protein was isolated from periplasm, purified by S-carboxymethylpapain affinity- and ion-exchange chromatography. The recombinant human kininogen domain 3 is 92% pure, reacts with anti-kininogen antibodies and is actively inhibitory. The expected amino acid sequence of ANSM-[G253-S377] kininogen was confirmed; the inhibitor has a molecular mass of 14,396 Da and an isoelectric point of 6.0 (pH). The determined Ki values of the complexes with papain and cathepsin L are similar to those measured previously with proteolytically liberated kininogen domain 3, and those of single-domain cystatins, like chicken egg white cystatin. However, recombinant kininogen domain 3 is a weak inhibitor of cathepsin B (Ki = 63 nM) as it has been found for native L-kininogen (Ki = 340 nM).

Identification of proteins absorbed to hemodialyser membranes from heparinized plasma

The protein layers formed during contact of plasma with hemodialysis membranes were studied. Dialysers having membranes of cellulose acetate (CA), saponified cellulose ester (SCE), cuprophane (CUP), polymethylmethacrylate (PMMA), and polyacrylonitrile (PAN) were used. Heparinized human plasma was recirculated through the dialysers for four hours. They were then rinsed and the proteins adsorbed to the membranes were eluted with 2% SDS. The yields of protein from the different membranes increased in the order: PMMA < CA < SCE < CUP < PAN. This is the probable order of increasing hydrophilicity. SDS-PAGE and Western blots were performed on the dialyser eluates. The blots were positive for most of the twenty proteins tested for. There were some interesting differences in adsorption patterns among the different membrane materials, notably for high molecular weight kininogen (HMWK), plasminogen and the C3 component of complement. HMWK was intact in the eluates from CA, CUP and SCE, whereas on PMMA and PAN there was evidence of cleavage, suggesting that activation of the contact phase of coagulation was more extensive on the latter two materials. Intact plasminogen was visible on all the blots. However, low molecular weight fragments were visible in the PAN eluates, suggesting activation of the fibrinolytic pathway. Low molecular weight fibrinogen fragments eluted from PAN membranes support this conclusion. C3 was visible in the blots obtained for all membrane materials, and the data suggest that complement is activated by all the membranes. A C3 fragment at about 30 kD (possibly C3d) was seen in the blots for the cellulosic membranes but not for PMMA or PAN.

Differential regulation of kininogen gene expression by estrogen and progesterone in vivo

Kininogens which have multifunctional domains, serve as the precursors of potent vasoactive kinin peptides and also function as cysteine proteinase inhibitors. Given its potential role in blood pressure homeostasis and inflammation, we have examined the regulation of rat kininogen gene expression by sex hormones in vivo. Our studies indicate a differential regulation of kininogen gene expression in rat liver by estrogen and progesterone. Northern and dot blot analysis using a rat low molecular weight kininogen cDNA probe show that kininogen mRNA levels in the liver of female rats are 4-fold higher than those in male rats. Ovariectomy results in a reduction of kininogen transcripts in the liver, while estradiol replacement of the ovariectomized rats increases kininogen mRNA levels. Similarly, Northern blot analysis using a kallikrein cDNA probe shows that estradiol treatment induces an increase of kallikrein gene expression in the kidney of the same animals. In contrast, progesterone treatment of the ovariectomized rats results in an increase in renal kallikrein mRNA levels while it reduces kininogen gene expression as compared to vehicle-treated ovariectomized animals. Immunoreactive kininogen levels in the serum, analyzed by a direct radioimmunoassay and Western blot, are increased by estradiol but slightly decreased by progesterone treatment. Western blot of serum proteins on a two-dimensional polyacrylamide gel reveals that in estradiol-treated ovariectomized rats, the levels of several 68,000 Da kininogens varying in charge are markedly higher than those in ovariectomized rats. The results indicate that estrogen is one of the determinants in regulating low molecular weight kininogen gene expression in vivo. The impact of estrogen-regulated kininogen expression on cardiovascular function awaits further investigation.

Inhibition of cell adhesion by high molecular weight kininogen

An anti-cell adhesion globulin was purified from human plasma by heparin-affinity chromatography. The purified globulin inhibited spreading of osteosarcoma and melanoma cells on vitronectin, and of endothelial cells, platelets, and mononuclear blood cells on vitronectin or fibrinogen. It did not inhibit cell spreading on fibronectin. The protein had the strongest antiadhesive effect when preadsorbed onto the otherwise adhesive surfaces. Amino acid sequence analysis revealed that the globulin is cleaved (kinin-free) high molecular weight kininogen (HKa). Globulin fractions from normal plasma immunodepleted of high molecular weight kininogen (HK) or from an individual deficient of HK lacked adhesive activity. Uncleaved single- chain HK preadsorbed at neutral pH, HKa preadsorbed at pH greater than 8.0, and HKa degraded further to release its histidine-rich domain had little anti-adhesive activity. These results indicate that the cationic histidine-rich domain is critical for anti-adhesive activity and is somehow mobilized upon cleavage. Vitronectin was not displaced from the surface by HKa. Thus, cleavage of HK by kallikrein results in both release of bradykinin, a potent vasoactive and growth-promoting peptide, and formation of a potent anti-adhesive protein.

Kinetics of bond cleavages at kallidin release by tissue kallikrein: cleavage of two peptide bonds in a single enzyme-substrate complex?

The kinetics of the release of kallidin, L- and KL-chains from bovine L-kininogen by porcine tissue kallikrein were followed and individual kinetic constants for cleavage of the Met-360 and the Arg-370 bond determined. The results suggest that both these bonds in L-kininogen r are hydrolyzed "simultaneously" without appearance of a free singly-nicked intermediate. Kallidin release in the human analogous system is also compatible with such a mechanism.

The structure and expression of the genes for T-kininogen in the rat

T-kininogen plays an important role in the acute phase response to trauma in the rat as a possible source of kinins and as a cysteine proteinase inhibitor. Two T-kininogens are expressed by rat liver from two separate genes. T-kininogen expression in liver during the acute phase response is regulated at the level of transcription. The similarity in T- and K-kininogen gene structure suggests divergent evolution from a common gene ancestor.

The sequence HGLGHGHEQQHGLGHGH in the light chain of high molecular weight kininogen serves as a primary structural feature for zinc-dependent binding to an anionic surface

The histidine-glycine-rich region of the light chain of cleaved high molecular weight kininogen (HK) is thought to be responsible for binding to negatively charged surfaces and initiation of the intrinsic coagulation, fibrinolytic, and kinin-forming systems. However, the specifically required amino acid sequences have not been delineated. An IgG fraction of a monoclonal antibody (MAb) C11C1 to the HK light chain was shown to inhibit by 66% the coagulant activity and by 57% the binding of HK to the anionic surface of kaolin at a concentration of 1.5 microM and 27 microM, respectively. Proteolytic fragments of HK were produced by successive digestion with human plasma kallikrein and factor XIa (FXIa). Those polypeptides that bound tightly (Kd = 0.77 nM) to a C11C1 affinity column were eluted at pH 3.0 and purified by membrane filtration. On 15% SDS polyacrylamide electrophoresis, the approximate M(r) was 7.3 kDa (range 6.2-8.1 kDa). Based on N-terminal sequencing, this polypeptide (1(2)), which extends from the histidine residue 459 to a lysine at position 505, 509, 511, 512, 515, or 520, inhibits by 50% the coagulant activity expressed by HK at a concentration of 22 microM. The synthetic peptide HGLGHGH representing the N-terminal of the 1(2)) fragment was synthesized, tested, and found at 4 mM to inhibit the procoagulant activity of HK 50%. A synthetic heptadecapeptide, HGLGHGHEQQHGLGHGH (residues 459-475) included within the 1(2) fragment, and with the ability to bind zinc, inhibited 50% of the HK coagulant activity at a concentration of 325 microM in the absence and presence of added Zn2+ (30 microM). The specific binding of 125I-HK to a negatively charged surface (kaolin) was inhibited 50% by unlabeled HK (5 microM). HGLGHGH, at a concentration of 7.0 mM, inhibited the binding to kaolin by 50%. The heptadecapeptide inhibited the specific binding of 125I-HK to kaolin by 50%, at a concentration of 2.3 mM, in the absence of Zn2+. In contrast, when Zn2+ was added, the concentration to achieve 50% inhibition decreased to 630 microM, indicating that Zn2+ was required to attain a favorable conformation for binding. Moreover, the 1(2) fragment was found to inhibit 50% of the 125I-HK binding to kaolin at a concentration of 380 microM. These results suggest that residues contained within the 1(2) fragment, notably HGLGHGHEQQHGLGHGH, serves as a primary structural feature for binding to a negatively charged surface.

Characterization of kininogens in human malignant ascites

Ascites from seven patients with advanced cancer were studied to characterize the kininogens. Immunological quantification of low molecular weight kininogen (L-kininogen) and high molecular weight kininogen (H-kininogen) by rocket immunoelectrophoresis showed values of 42% and 39%, respectively, compared to control plasma. Release of kinin from the ascites samples was assayed on an isolated rat uterus. The total kinin released from the kininogens was 39% of the value in control plasma, while release selectively from H-kininogen amounted to 25% of plasma. This indicates about 30% of the bradykinin in H-kininogen to be released in vivo in ascites, and points to kinins as possible mediators of the increased vascular permeability causing accumulation of ascites. The function of kininogens as cysteine protease inhibitors (CPIs) was assayed as well, indicating that both L- and H-kininogen function as cysteine protease inhibitors in human ascitic fluid. The proteolytic cleavage of H-kininogen in ascites was studied by polyacrylamide gel electrophoresis and subsequent immunoblotting. H-kininogen was extensively cleaved in ascites compared to control plasma, with large amounts present of a degraded form with Mr of 99 kDa. The bands observed compared well with those described in plasma, and are consistent with contact activation taking place in ascites.

The cystatins: protein inhibitors of cysteine proteinases

The last decade has witnessed enormous progress of protein inhibitors of cysteine proteinases concerning their structures, functions and evolutionary relationships. Although they differ in their molecular properties and biological distribution, they are structurally related proteins. All three inhibitory families, the stefins, the cystatins and the kininogens, are members of the same superfamily. Recently determined crystal structures of chicken cystatin and human stefin B established a new mechanism of interaction between cysteine proteinases and their inhibitors which is fundamentally different from the standard mechanism for serine proteinases and their inhibitors.

Kinin-generating cascade in advanced cancer patients and in vitro study

The role of the bradykinin-generating system in the pathogenesis of cancer was explored by simultaneously measuring plasma prekallikrein (PK), the precursor of kallikrein, which is the major enzyme responsible for kinin generation, and plasma kininogens (KNG), which are precursors of kinin, in patients with various cancers. The mean value of plasma PK in healthy volunteers was 2.5 +/- 0.5 (mean +/- SD) units/mg plasma protein and that in cancer patients (all stage IV) was 1.7 +/- 0.7 units/mg plasma protein. The mean value of plasma KNG in healthy volunteers was 12.5 +/- 2.0 ng kinin equivalents/mg plasma protein and that in cancer patients was 10.9 +/- 2.8 ng. These data showed that plasma PK and plasma KNG values were significantly lower in cancer patients compared with healthy volunteers (P less than or equal to 0.005 for PK; 0.0005 less than P less than or equal to 0.005 for KNG; n = 28 for healthy subjects; n = 29 for cancer patients). These data appear to indicate that conversion of PK to kallikrein would probably occur with concomitant consumption of KNG by newly generated kallikrein for kinin generation in cancer patients. Early stage cancer patients showed little difference from healthy volunteers. For the in vitro study, activation of purified Hageman factor (HF) and PK was examined by using cancer cell lines and virus-transformed cells that produced plasminogen activator (PA) at a high rate. Both HF and PK were activated in the presence of plasminogen. Diploid cell lines and primary fibroblasts, which did not produce PA, activated neither HF nor PK. Taking all these data together, we conclude that kinin generation does occur in the plasma of patients with advanced cancer, and that one of the initiation mechanisms of the kinin-generating cascade appears to be mediated by plasmin and to depend on cancer cell-derived PA activity.

Sex dimorphism and inflammatory regulation of T-kininogen and T-kininogenase

Studies were carried out in order to better understand hormonal and inflammatory regulation of the T-kininogen and T-kininogenase system. T-kininogen from rat serum and T-kininogenase from rat submandibular gland were purified to homogeneity, and specific antisera to the purified proteins were generated. Simple, sensitive and specific radioimmunoassays were developed for measuring both T-kininogen and T-kininogenase. The assays incorporated a modified poly(ethylene glycol) technique for separating free from antibody-bound forms. Optimal combinations of poly(ethylene glycol) and gamma-globulin were found, yielding low background and high specific binding. The assays can detect a minimum of 160 pg of T-kininogen and 80 pg of T-kininogenase per tube. Serial dilutions of sera from normal and turpentine-treated rats showed complete parallelism with the T-kininogen standard curve. T-kininogen levels in rat serum and rat tissues increased more than 10-fold following turpentine treatment, while T-kininogenase levels in the submandibular gland and other tissues remained unchanged. Through use of a kinin-directed kininogen monoclonal antibody, Western blots of two-dimensional gels of serum following acute inflammation showed increased levels of several kininogens which vary in both molecular weight and isoelectric point. Analysis of serum kininogen levels shows sexual dimorphism, with female rats having 3.9-fold higher levels than males. Contrarily, T-kininogenase levels in the submandibular gland of male rats are 2.4-fold higher than those in females. The studies also showed that the T-kininogen and T-kininogenase system is regulated by sex hormones. T-kininogen is an acute-phase protein whose rapid increase and mobilization following inflammation may provide a primary defense against proteolytic damage during trauma.

Ornitho-kininogen and ornitho-kinin: isolation, characterization and chemical structure

Ornitho-kininogen was purified from chicken and duck blood plasmas by a two-stage method using chromatography on columns of S-alkylated papain-Cellulofine and DEAE-5PW. The isolated preparation from chicken plasma gave a single band on SDS-PAGE with or without 2-mercaptoethanol and on disc-PAGE. The molecular weight of ornitho-kininogen was estimated as 74,000 on SDS-PAGE using the Ferguson plot method. Ornitho-kininogen was found to have the similar properties to those of mammalian high molecular weight kininogen (HMWK), in terms of the amino acid composition, molecular weight, and susceptibility to plasma kallikrein. No kininogen corresponding to mammalian low molecular weight kininogen (LMWK) and rat T-kininogen could be detected in chicken plasma. In fact, ornitho-kininogen was degraded rapidly by bovine plasma kallikrein, liberating a kinin. This kinin was isolated from the digest by reversed-phase HPLC. The primary structure of the isolated kinin was determined as Arg-Pro-Pro-Gly-Phe-Thr-Pro-Leu-Arg. The sequence of this peptide, named ornitho-kinin, was similar to that of bradykinin except for the substitution of Thr-6 and Leu-8 for Ser-6 and Phe-8. The isolated ornitho-kinin induced a contraction of chicken smooth muscle and had a strong hypotensive effect in the chicken. However, it did not contract the isolated rat uterus. It is suggested that this specificity difference is due to the replacement of Phe-8 by Leu-8. The sequence of residues 1-30 of ornitho-kininogen exhibited 43% identity with that of bovine kininogen.

Circulating bradykinin-like immunoreactivity and the pentagastrin-induced carcinoid flush

Bradykinin and structurally related peptides are potent vasodilators and a role for these kinins in the aetiology of the carcinoid flush has been proposed. Using an antiserum directed against the COOH-terminal region of bradykinin in radioimmunoassay, the concentrations of bradykinin-like immunoreactivity in extracts of peripheral blood were compared in patients with carcinoid syndrome (n = 11) and healthy subjects (n = 6). In the fasted state, the concentrations of bradykinin-like immunoreactivity in the patients (10 +/- 5 ng/l) were not significantly different from the concentrations in healthy subjects (6 +/- 3 ng/l). An intravenous injection of pentagastrin (0.6 micrograms/kg) provoked a flush of differing degrees of severity in all patients. In four patients, the flush was concurrent with large rises (277-, 26-, 11- and 10-fold over mean basal values) in bradykinin-like immunoreactivity that was resolved by high performance liquid chromatography into lysyl-bradykinin and bradykinin (approximate ratio 1:2). In two patients, small rises in immunoreactivity (2.4- and 1.7-fold) occurred after the flush and in the remaining five patients no rise in bradykinin-like immunoreactivity was measured. In the healthy subjects, the pentagastrin injection did not provoke a flush and no rises in bradykinin-like immunoreactivity were observed. The data support earlier results obtained using bioassays that the carcinoid flush in some patients is associated with the appearance in blood of bradykinin-related peptides. It has been shown, however, that these kinins cannot be the sole causative agent of the flush. It is suggested, therefore, that the aetiology of the flush is probably multi-factorial.

Non-enzymatic glycation of antithrombin III in vitro

Non-enzymatic glycation of antithrombin III (AT-III) has been proposed as a significant contributor to the increased incidence of thrombo-occlusive events in diabetics. AT-III, isolated from normal human plasma by means of heparin affinity and ion-exchange chromatography, was incubated with 0-0.5 M glucose in neutral phosphate buffer at 37 degrees C. The extent of non-enzymatic glycation could be monitored by uptake of radioactivity as well as by binding to a phenylboronate affinity resin, which effectively retards AT-III containing ketoamine-linked glucose. Non-enzymatically glycated AT-III (approx. 1 mol glucose/mol protein) bound heparin nearly as efficiently as non-glycated AT-III. The two AT-III preparations were equally active in inhibiting thrombin cleavage of chromogenic substrate. Following incubation with [14C]glucose, structural analyses of cyanogen-bromide-cleaved peptides of enzymatically glycated AT-III showed that the [14C]glucose adducts were distributed over many sites on the molecule. This lack of specificity contrasts with the restricted sites of modification on hemoglobin, albumin and ribonuclease A, and explains why non-enzymatic glycation of AT-III has little if any effect on its function.

A secretable serine proteinase with highly restricted specificity from cytolytic T lymphocytes inactivates retrovirus-associated reverse transcriptase

TSP-1, a murine T cell specific proteinase, is expressed in cytolytic T lymphocytes and secreted upon their interaction with antigen bearing target cells. In searching for possible extracellular substrates of the enzyme in the physiological environment of cytolytic effector cells, we have investigated the proteolytic activity of TSP-1 on retroviral proteins. It is shown that reverse transcriptase derived from the retrovirus Moloney murine leukemia virus is inactivated by TSP-1 via limited proteolysis. The data suggest the possibility that cytolytic T lymphocytes are able to interfere with retroviral replication by secreting a serine proteinase which degrades viral proteins.

Rapid isolation of human kininogens

A rapid, two-step procedure is described for the isolation of both "high molecular weight" (H-) and "low molecular weight" (L-) plasma kininogens from a single sample of plasma. Affinity chromatography on carboxymethyl-papain-Sepharose is used, together with high-resolution anion exchange chromatography.

Acute phase responses of plasma angiotensinogen and T-kininogen in rats

Acute phase responses of plasma angiotensinogen and kininogen were studied in rats. Plasma angiotensinogen levels increased about 3-fold during the first 8 hr, and returned to normal at 48 hr, following the induction of acute inflammation by lipopolysaccharide (LPS). Plasma kininogen reached maximum levels at 48 hr following LPS administration. In adrenalectomized rats, plasma angiotensinogen levels decreased significantly, and the administration of LPS did not elevate plasma angiotensinogen levels. In contrast, plasma kininogen levels were increased by adrenalectomy, as well as by sham-operation. Dexamethasone significantly increased plasma angiotensinogen levels in adrenalectomized rats as well as in normal rats, but aldosterone did not. Plasma kininogen levels of normal rats were not changed by the administration of dexamethasone or aldosterone. From these results, it was concluded that the acute phase response of plasma angiotensinogen is mediated by glucocorticoid, but that of plasma kininogen is not.

Involvement of inflammatory leukocytes in hepatic induction of T-kininogen in rat

Hepatic synthesis as well as plasma levels of T-kininogen, a protein precursor of T-kinin (Ile-Ser-bradykinin), increase in rats following the induction of acute inflammation. Studies have been undertaken to elucidate an involvement of inflammatory leukocytes in the acute-phase response of T-kininogen. Peritoneal exudate cells (PEC) were prepared from rats six days after the intraperitoneal injection of Freund's complete adjuvant. By transfer of these leukocytes into the peritoneal cavity of normal rats, plasma kininogen levels of these recipients increased about threefold after one day. Secretion of kininogen from rat hepatocytes in primary culture was enhanced about twofold by coculturing with PEC. A similar effect was also obtained by adding culture supernatant of these leukocytes into hepatocytes, and the increased levels of kininogen in culture medium of hepatocytes was due to the increased levels of T-kininogen. From these results, it was concluded that leukocytes in the inflammatory site, probably macrophages, release some substance(s) which stimulate(s) the hepatic synthesis of T-kininogen.

Effects of secondary interactions on the kinetics of peptide and peptide ester hydrolysis by tissue kallikrein and trypsin

Kinetic constants for the hydrolysis by porcine tissue beta-kallikrein B and by bovine trypsin of a number of peptides related to the sequence of kininogen (also one containing a P2 glycine residue instead of phenylalanine) and of a series of corresponding arginyl peptide esters with various apolar P2 residues have been determined under strictly comparative conditions. kcat and kcat/Km values for the hydrolysis of the Arg-Ser bonds of the peptides by trypsin are conspicuously high. kcat for the best of the peptide substrates, Ac-Phe-Arg-Ser-Val-NH2, even reaches kcat for the corresponding methyl ester, indicating rate-limiting deacylation also in the hydrolysis of a peptide bond by this enzyme. kcat/Km for the hydrolysis of the peptide esters with different nonpolar L-amino acids in P2 is remarkably constant (range 1.7), as it is for the pair of the above pentapeptides with P2 glycine or phenylalanine. kcat for the ester substrates varies fivefold, however, being greatest for the P2 glycine compounds. Obviously, an increased potential of a P2 residue for interactions with the enzyme lowers the rate of deacylation. In contrast to results obtained with chymotrypsin and pancreatic elastase, trypsin is well able to tolerate a P3 proline residue. In the hydrolysis of peptide esters, tissue kallikrein is definitely superior to trypsin. Conversely, peptide bonds are hydrolyzed less efficiently by tissue kallikrein and the acylation reaction is rate-limiting. The influence of the length of peptide substrates is similar in both enzymes and indicates an extension of the substrate recognition site from subsite S3 to at least S'3 of tissue kallikrein and the importance of a hydrogen bond between the P3 carbonyl group and Gly-216 of the enzymes. Tissue kallikrein also tolerates a P3 proline residue well. In sharp contrast to the behaviour of trypsin is the very strong influence of the P2 residue in tissue-kallikrein-catalyzed reactions. kcat/Km varies 75-fold in the series of the dipeptide esters with nonpolar L-amino acid residues in P2, a P2 glycine residue furnishing the worst and phenylalanine the best substrate, whereas this exchange in the pentapeptides changes kcat/Km as much as 730-fold. This behaviour, together with the high value of kcat/Km for Ac-Phe-Arg-OMe of 3.75 X 10(7) M-1 s-1, suggests rate-limiting binding (k1) in the hydrolysis of the best ester substrates.(ABSTRACT TRUNCATED AT 400 WORDS)