On the various forms of the glandular kallikrein from autolyzed porcine pancreas

Kallikrein and kallikrein-like proteinases: purification and determination by chromatographic and electrophoretic methods

Kallikreins and kallikrein-like enzymes make up a family of serine proteinases present in tissues and body fluids of mammals and in some snake venoms. This review deals with the procedures of purification, detection and determination of these enzymes by chromatographic and electrophoretic methods. The procedures are reported in tables, described and discussed with the aim of illustrating the state-of-the-art of research in the field.

Purification of a second kallikrein from bovine pancreas

Two kallikreins were identified in a homogenate of bovine pancreas in terms of their differential elution from an anion-exchange chromatography column. The kallikreins were quantified by their ability to release kinin from a partially purified preparation of bovine kininogen. The second kallikrein, designated kallikrein B, was purified by a three-step procedure following anion-exchange chromatography consisting of affinity chromatography on a benzamidine-agarose resin, gel filtration and hydrophobic interaction chromatography. An overall purification factor of 556-fold was achieved with a 58% recovery of enzymatic activity. The final material was shown to be homogeneous by a number of electrophoretic analyses. The relative molecular mass of pro-kallikrein B was found to be 26,700 by gel filtration and that of kallikrein B to be 26,000 by SDS gel electrophoresis. Gel isoelectric focusing revealed the presence of several isoenzymic forms ranging in isoelectric point from pH 4.05 to 4.35.

New specific assays for tonin and tissue kallikrein activities in rat submandibular glands. Assays reveal differences in the effects of sympathetic and parasympathetic stimulation on proteinases in saliva

At least fourteen separate bands of proteinase activity, labelled A-N, were identified by an enzyme overlay membrane technique, using oligopeptide-7-amino-4-trifluoromethylcoumarin (AFC) substrates in rat submandibular gland extracts fractionated on pH 4-6.5 isoelectric focusing gels. The proteinases were eluted into an ammonium bicarbonate buffer pH 9.8 containing 0.1% Triton X-100 and the relative contribution of each band to total activity evaluated using D-Val-Leu-Arg-AFC (DVLR-AFC) and Z-Val-Lys-Lys-Arg-AFC (ZVKKR-AFC) as substrates. Immunoblotting of band eluants run on sodium dodecyl sulphate gels with antibodies showed that band A was identical with tonin and bands K-N contained tissue kallikrein. Tonin was found to hydrolyse ZVKKR-AFC but not DVLR-AFC. Estimates of the Km values of tissue kallikrein for DVLR-AFC and tonin for ZVKKR-AFC were found to be similar (approx. 20 microM) yet the former enzyme hydrolysed its substrate five times faster. Tonin was inhibited by soybean trypsin inhibitor (SBTI) but not by aprotinin. Tissue kallikrein, on the other hand, was inhibited by aprotinin but was considerably more resistant to inhibition by SBTI. In tissue extracts 95% of the ZVKKR-AFC lytic activity in the presence of 1 microM aprotinin is due to tonin and a similar percentage of the DVLR-AFC hydrolysing activity in the presence of 10 microM SBTI is due to tissue kallikrein. These findings were used for the specific measurement of these two proteinases in submandibular gland extracts and in saliva without prior purification. Using these inhibitor based assays we revealed qualitative differences in the composition of proteinases secreted into saliva during parasympathetic versus sympathetic stimulation of the submandibular gland. The distribution of proteinases in sympathetic saliva is very similar to that found in submandibular extracts but on parasympathetic stimulation, although much less proteinase is released, the contributions of the more acidic isomers of tissue kallikrein are increased and that of tonin and other proteinases dramatically decreased. The data suggest that parasympathetic and sympathetic nerves induce proteinase secretion via different pathways.

Rat urinary kallikrein localization in kidney: effects of fixation

The influence of fixation on the immunocytochemical localization of tissue kallikrein in the kidney has been evaluated using both monoclonal and polyclonal antibodies. These studies have provided several results relevant to kallikrein localization in kidney: (1) the intensity and distribution of immunostaining with both polyclonal and monoclonal anti-kallikrein antibodies is fixation-dependent; (2) the most intense and consistent localizations of kallikrein are in the connecting tubule and the cortical collecting duct of the nephron; (3) kallikrein-like immunoreactivity is seen in proximal tubules with polyclonal but not with non-cross-reactive monoclonal antibodies; and (4) fixatives which disrupt membranes reveal a kallikrein-like antigen in straight tubules of the outer medulla. However, immunostaining with monoclonal antibodies indicates that much of the observed immunostaining at this site probably represents cross-reactivity with another member of the kallikrein family of enzymes.

Comparative specificity of porcine pancreatic kallikrein and bovine pancreatic trypsin. Importance of interactions N-terminal to the scissible bond

Hydrolyses catalyzed by bovine pancreatic trypsin and porcine pancreatic kallikrein were studied using synthetic peptide substrates of the type E chi-L chi 2-L chi 1 decreases Y and E chi-L chi 3-L chi 2-L chi 1 decreases Y with L chi 1 = Arg defining the hydrolysis position (indicated by the arrow). The leaving moiety Y was -OCH3, -NH-C6H4-p-NO2 and -Ala-NH2. Insight into interactions occurring between the active site of the enzymes and the acyl moiety of the substrates was gained by studying the influence on hydrolysis rate of structural variation of residues L chi 2 and L chi 3. Parallel analyses of the hydrolyses of the ester, anilide, and peptide substrates having the same acyl moiety considerably facilitated the interpretation of the kinetic data. Trypsin, but not kallikrein, displayed high reactivity even with relatively short substrates. Ac-Ala-Arg-Ala-NH2, for example, was a better substrate for trypsin than for kallikrein by a factor of 1.3 X 10(4) in terms of kcat and 5.9 X 10(4) in terms of kcat/Km. Reactivity differences of such magnitude were related to two main differences in enzyme-substrate interactions: the interaction of the arginine side chain of the substrate with the specificity pocket of the enzyme is optimal for trypsin but poor for kallikrein and the number of hydrogen bonds formed by the enzyme with the backbone section of the substrate on both sides of the specific residue is larger in the case of trypsin. The latter difference is found to be related to the structure of amino-acid residue 192 which is glutamine in trypsin and methionine in kallikrein.

Rat submaxillary gland serine protease, tonin. Structure solution and refinement at 1.8 A resolution

Tonin is a mammalian serine protease that is capable of generating the vasoconstrictive agent, angiotensin II, directly from its precursor protein, angiotensinogen, a process that normally requires two enzymes, renin and angiotensin-converting enzyme. The X-ray crystallographic structure determination and refinement of tonin at 1.8 A resolution and the analysis of the resulting model are reported. The initial phases were obtained by the method of molecular replacement using as the search model the structure of bovine trypsin. The refined model of tonin consists of 227 amino acid residues out of the 235 in the complete molecule, 149 water molecules, and one zinc ion. The R-factor (R = sigma Fo - Fc/sigma Fo) is 0.196 for the 14,997 measured data between 8 and 1.8 A resolution with I greater than or equal to sigma (I). It is estimated that the overall root-mean-square error in the coordinates is about 0.3 A. The structure of tonin that has been determined is not in its active conformation, but one that has been perturbed by the binding of Zn2+ in the active site. Zn2+ was included in the buffer to aid the crystallization. Nevertheless, the structure of tonin that is described is for the most part similar to its native form as indicated by the close tertiary structural homology with kallikrein. The differences in the structures of the two enzymes are concentrated in several loop regions; these structural differences are probably responsible for the differences in their reactivities and specificities.

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)

Anterior pituitary glandular kallikrein: trypsin activation and estrogen regulation

Discrepant reports exist regarding the presence of glandular kallikrein or other trypsin-like serine proteases in the pituitary. The existence of pituitary kallikreins in latent forms could explain these discrepancies. I report that trypsin treatment of rat anterior pituitary homogenates activates two serine proteases which generate kinins from kininogen and selectively cleave chromogenic substrates for kallikreins. One protease (enzymatically and immunologically resembling glandular kallikrein) and activated 5-fold by trypsin and was 20 times more abundant in female than in male lobes due to hormonal regulation by ovarian estrogens. The second kallikrein (activated 20-fold by trypsin) was unaffected by estrogens. The results demonstrate that rat anterior pituitary kallikreins predominantly exist in latent forms requiring activation for detection. Additionally, glandular kallikrein is a major estrogen-induced protein in the rat anterior pituitary. No other member of this large protease family is known to be regulated by estrogens.

A comparative study of prokallikreins and kallikreins from rat pancreatic tissue and juice

Two zymogens, designated prokallikreins A and B, were isolated from homogenates of rat pancreatic tissue. The two forms of prokallikrein were found to be very similar in size and charge properties. They gave rise to very similar kallikreins on activation with exogenous trypsin. Differences in carbohydrate content of the two zymogens were probably responsible for differences seen in their behaviour on ion-exchange chromatography and immunoelectrophoresis. In contrast, only one form of prokallikrein was isolated from rat pancreatic juice. It showed almost identical behaviour on ion-exchange chromatography and identical mobility on electrophoresis to prokallikrein A. Thus it can be tentatively suggested that it is prokallikrein A which is secreted into the pancreatic juice and represents the physiologically important zymogen.

Kininogenase activity of tonin

Tonin, known for its specific and direct generation of angiotensin II, was highly purified from rat submaxillary gland and investigated for kininogenase activity. For the substrate, heat-treated plasma from ox blood, and highly purified low-molecular-weight (LMW) and high-molecular-weight (HMW) kininogens, were used. The reaction product formed at pH 8.0 well satisfied the characteristics of kinin, i.e., depressor and oxytocic activities and reactivity with antibradykinin antiserum. Kinin formed by tonin from purified LMW kininogen was identified with bradykinin in high performance liquid chromatography and radioimmunoassay. The results revealed tonin's new capability of forming kinin in addition to the hitherto known pressor angiotensin II, indicating tonin, too, is a member of the "kinin- tensin enzyme system."

The pH dependence of pre-steady-state and steady-state kinetics for the porcine pancreatic β-kallikrein-B-catalyzed hydrolysis of p-nitrophenyl ester

Pre-steady-state and steady-state kinetics of the porcine pancreatic beta-kallikrein-B (EC 3.4.21.35) catalyzed hydrolysis of ZArgONp have been determined between pH 2.4 and 8. The results are consistent with a minimum three-step mechanism involving an acyl-enzyme intermediate: (see formula). The formation of the E X S complex may be regarded as a pseudoequilibrium process; the minimum values for k+1 are 5.9 X 10(6) M-1 X s-1 (pH 5.5) and 9.4 X 10(5) M-1 X s-1 (pH 2.4) and that for k-1 is 600 s-1. The value of k-1/k+1 (= Ks) changes from 102 microM at pH greater than or equal to 5.5 to 638 microM at pH less than 2.4. The pH dependence of k+2 conforms to two ionizing groups, in the E X S complex, with pKa values of 3.4 +/- 0.1 and 7.05 +/- 0.10. The pH profile of k+2/Ks (= kcat/Km) reflects the ionization of two groups, in the free enzyme, with pKa values of 4.2 +/- 0.1 and 7.05 +/- 0.10. The pH dependence of k+3 implicates two ionizing groups in the deacylation step with pKa values of 4.6 +/- 0.1 and 7.0 +/- 0.1. At acid pH values (pH 2.4-4.4), k+3 is rate-limiting in catalysis, whereas for pH values higher than 4.4, k+2 becomes rate-limiting. The observed neutral and acid ionizations probably reflect the acid-base equilibrium of His-57 and Asp-189 involved in the central site of beta-kallikrein-B. The structural basis for the specificity and catalytic behaviour of this proteinase are discussed and a role for Ser-226 is pinpointed.

Purification and properties of guinea-pig submandibular-gland kallikrein

Guinea-pig submandibular kallikrein has been purified from the glands to electrophoretic homogeneity by conventional procedures. The enzyme is active as a kininogenase, releasing kallidin at a rate of 462 micrograms/min per mg of protein from bovine kininogen, and proved potently hypotensive in the guinea pig and in the dog, properties which indicate its tissue kallikrein nature. The specific activity determined on the substrate N-alpha-benzoyl-L-arginine ethyl ester (11.1 mumol/min per mg of protein) is much lower than that measured with N-acetyl-L-phenylalanyl-L-arginine ethyl ester (483 mumol/min per mg of protein). The latter value is of an order of magnitude comparable with the specific activities of other tissue kallikreins determined with this sensitive kallikrein substrate. The enzyme is a glycoprotein consisting of 237 amino acid residues and containing three to four glucosamine molecules. Its amino acid composition is not identical with that reported for guinea-pig coagulating-gland kallikrein, but is remarkably similar to that of the porcine tissue kallikreins. Apparent Mr values are 29000 (sodium dodecyl sulphate/polyacrylamide-gel electrophoresis) or 34000 (gel filtration). The amino acid sequence of the first 31 N-terminal residues was determined and was found to be closely homologous with that of other tissue kallikreins.

Effect of antithrombin III, alpha 1-proteinase inhibitor and heparin on amidolytic activity of nerve growth factor (7S-NGF)

Amidolysis catalysed by nerve growth factor (7S-NGF) and by a glandular kallikrein, unlike that catalysed by thrombin, was not inhibited by antithrombin III, either in the presence or absence of heparin. Inhibition by alpha 1-proteinase inhibitor of thrombin-, but not of 7S-NGF- or kallikrein-catalysed amidolysis was alleviated by incubation of enzyme and heparin before addition of inhibitor. These data are discussed in terms of a possible control of growth factor activity by antiproteinases and glycosaminoglycans.

The complete amino acid sequence of low molecular mass urokinase from human urine

The sequence of all 253 amino acids of the heavy (B-) chain of human urinary urokinase was determined. The fragmentation strategy employed included cyanogen bromide cleavage of S-carboxymethylated B-chain at Met and/or Trp residues, cleavage of acid-labile Asp-Pro bonds, and the use of the specific endoproteinases Lys-C and Arg-C for generation of overlapping fragments. For sequence determination automated solid- or liquid-phase techniques of Edman degradation were used. The amino acid sequence obtained substantiates the serine protease character of the B-chain of urokinase: a considerable homology with other serine proteinases, especially with the B-chain of human plasmin, was proved. The pertinent active site amino acids were localized: His-46, Asp-97, and Ser-198. A carbohydrate side chain, containing at least 4 glucosamine and 2 galactosamine residues, was demonstrated to be fixed at asparagine in position 144. The sequence data presented, together with the sequence of the second (A1-) chain of low molecular mass urokinase which was reported by us in an earlier communication, complete the knowledge of the whole primary structure of an active form of human urinary urokinase.