A sensitive colorimetric assay for human urinary kallikrein

VARIATIONS IN KALLIKREIN-LIKE ESTERASE ACTIVITY IN DIFFERENT SEGMENTS OF THE RAT NEPHRON DURING SALT-LOAD AND SALT-DEPLETION

Histochemical changes in kallikrein-like activity in the rat nephron induced by chronic salt-load or salt-depletion were investigated semiquantitatively, using a synthetic substrate for kallikrein, pro-phe-arg-naphthylester. The location of the changes in the different segments of the nephron was established by comparison with neighbouring freeze-dried sections, where the various structures of the tubular segments were identified. The enzyme activity was graded semiquantitatively and the percentage of tubular segments possessing enzyme activity was recorded. In salt-loaded rats, the enzyme activity in the deep half of the renal cortex was decreased in the first and second segments of the proximal tubule as well as in the third segment in the cortex. In salt-depleted rats, the enzyme activity in the deep half of the renal cortex was also decreased in the first segment of the proximal tubule as well as in the third segment in the cortex. In contrast, the enzyme activity in the second segment of the proximal tubule was increased in the superficial cortex as well as in the deep cortex. Furthermore, in the salt-depleted rats the enzyme activity was decreased in the cortical part of the ascending thick limb of Henle, but increased in the medullary part. In the superficial part of the cortex, the enzyme activity was decreased in the distal convoluted tubule. In the kidneys from both salt-loaded and salt-depleted rats, the differences in enzyme activity between zones--such as found in the normal kidney--disappeared in the case of the first and second segments of the proximal tubule. However, in the other segments of the nephron, the zonal differences were preserved in both experimental conditions.

Direct determination of kallikrein by high-performance liquid chromatography

A direct and specific identification of porcine pancreatic kallikrein by high-performance hydrophobic chromatography is proposed; the minimum amount which can be injected is 2.5 U. An application to the quantitative determination of the enzyme by high-performance size-exclusion chromatography is reported; the method is precise with a mean coefficient of variation of 2.8% and the minimum amount which can be injected is 0.02 U of kallikrein. The results obtained with determinations in real biological samples (porcine pancreatic powder and human urine) are reported. The method is based on direct and specific chromatographic signals and does not destroy the biological activity of this enzyme.

Increased renal TXA2 synthesis in diabetes mellitus: simultaneous determination of urinary TXB2 and 2,3-dinor-TXB2

The present study was designed to determine urinary excretion of kallikrein(KAL)-kinin as well as prostaglandin (PG) E2, TXB2 and 2,3-dinor-TXB2, a major urinary metabolite of TXA2 synthesized in platelets, by specific RIAs in patients with diabetes mellitus (DM). KAL or kinin excretion in 26 type II DM did not differ from control values obtained in 18 age-matched healthy subjects (C), although DM with HbA1 greater than 11% excreted less KAL. Urinary PGE2 excretion (7.6 +/- 2.8 ng/mg creatinine, mean +/- SE) was significantly lower in DM compared to C (17.5 +/- 3.9, p less than 0.05), while DM excreted more TXB2 (0.57 +/- 0.09, p less than 0.01) and 2,3-dinor-TXB2 (0.56 +/- 0.12, N.S.) than C (0.19 +/- 0.02 or 0.33 +/- 0.01). DM with or without mild proteinuria demonstrated lower PGE2, but higher TXB2 and 2,3-dinor-TXB2 excretion. A positive correlation of TXB2/2,3-dinor-TXB2 with proteinuria was observed in this group. However, in DM with massive proteinuria over 500 micrograms/mg creatinine, TXB2 and 2,3-dinor-TXB2 excretion decreased to levels almost identical to C. As a whole, a ratio of TXB2 to PGE2 or 2,3-dinor-TXB2 in DM was significantly higher than in C. The results suggest that a relative preponderance of TXB2 to 2,3-dinor-TXB2 may indicate an augmented renal, in addition to platelet, TXA2 synthesis. An excessive vasoconstrictive and proaggregatory TXA2 renal synthesis, concomitant with a decrease in vasodilatory and antiaggregatory PGE2, may have profound effects on renal functions such as protein excretion in DM.

Isolation of [hydroxyproline3]Lysyl-bradykinin formed by kallikrein from human plasma protein

[Hydroxyproline3]Lysyl-bradykinin ([Hyp3]Lys-BK), a new kinin was isolated, besides Lysyl-bradykinin (Lys-BK), from the reaction mixture of human plasma protein Cohn's fraction IV-4 with hog pancreatic kallikrein. The liberated kinins were isolated by procedures including ethanol extraction, Sephadex G-15, CM cellulose and reverse-phase high performance liquid chromatography and quantitated by radioimmunoassay. On HPLC, two peaks of immunoreactive kinins emerged. Peak 1, an unknown kinin proceeded to peak 2 which had an identical retention time to that of Lys-BK. The amino acid sequence of the unknown peak 1 proved to be Lys-Arg-Pro-Hyp-Gly-Phe-Ser-Pro-Phe-Arg, or [Hydroxyproline3]Lys-BK, and peak 2 Lys-BK. The ratio of the amounts of two kinins thus formed were [Hyp3]Lys-BK 25 +/- 4% and Lys-BK 75 +/- 4%. The existence of [Hyp3]Lys-BK suggests a presence of a new kininogen containing [Hyp3]Lys-BK in human plasma protein.

Effect of oral potassium on urinary kallikrein excretion in essential hypertension

Urinary kallikrein and potassium were excreted in parallel in not only static but also dynamic sodium states. Oral potassium load stimulated the release of urinary kallikrein in normotensive subjects and WHO stage I essential hypertensive patients. Stage II essential hypertensive patients had the lowest value of basal level of urinary kallikrein and showed no increase in urinary kallikrein by oral potassium load. These results suggest that the functional activity of renal kallikrein-kinin system decreases with the development of essential hypertension.

Identification of [hydroxyproline3]-lysyl-bradykinin released from human plasma protein by kallikrein

[Hydroxyproline3]-lysyl-bradykinin [( Hyp3]-Lys-BK), a new kinin was isolated, besides lysyl-bradykinin (Lys-BK), from the reaction mixture of human plasma protein Cohn's fraction IV-4 with hog pancreatic kallikrein. The liberated kinins were isolated by procedures including ethanol extraction, Sephadex G-15, CM cellulose and reverse-phase high performance liquid chromatography (HPLC) and quantitated by radioimmunoassay. On HPLC, two peaks of immunoreactive kinins emerged. Peak 1, an unknown kinin proceeded to Peak 2 which had an identical retention time to that of Lys-BK. The amino acid sequence of the unknown Peak 1 proved to be Lys-Arg-Pro-Hyp-Gly-Phe-Ser-Pro-Phe-Arg, or [Hyp3]-Lys-BK, and Peak 2 Lys-BK. The ratio of the amounts of two kinins thus formed were [Hyp3]-Lys-BK 25 +/- 4% and Lys-BK 75 +/- 4%. The existence of [Hyp3]-Lys-BK suggests a presence of a new kininogen, containing [Hyp3]-Lys-BK in human plasma protein, possibly undergone post-translational modifications.

Renal kallikrein in diabetic patients with hypertension accompanied by nephropathy

We measured the 24-h excretion of urinary kallikrein in 27 patients with Type 2 (non-insulin-dependent) diabetes and in 10 normal control subjects. Mean (+/- SD) kallikrein excretion in diabetic patients with nephropathy (6.2 +/- 2.4 naphthyl units (NU)/day, n = 13) was significantly lower than in control subjects (12.8 +/- 3.4 NU/day, p less than 0.01) and in diabetic patients without nephropathy (9.4 +/- 3.4 NU/day, n = 14, p less than 0.05). Kallikrein excretion in hypertensive diabetic patients with nephropathy (5.1 +/- 1.6 NU/day, n = 8) was significantly lower (p less than 0.05) than in normotensive patients with nephropathy (8.3 +/- 2.1 NU/day, n = 5). There were no significant differences in kallikrein excretion rate (24-h excretion of urinary kallikrein/24-h creatinine clearance) among control subjects (9.9 +/- 4.3 NU/ml), diabetic patients with (9.0 +/- 3.2 NU/ml) and without (9.3 +/- 3.5 NU/ml) nephropathy. However, kallikrein excretion rate in hypertensive diabetic patients with nephropathy (7.7 +/- 3.3 NU/ml) was significantly lower (p less than 0.05) than in normotensive diabetic patients with nephropathy (11.8 +/- 2.0 NU/ml, n = 10). Respective basal and post-stimulated (with intravenous furosemide 40 mg plus 60 min ambulation) plasma aldosterone concentrations measured in control subjects and in hypertensive diabetic patients with nephropathy were similar and increased to the same extent in the 2 groups (5.5 +/- 3.2 versus 5.3 +/- 3.2 and 9.3 +/- 2.6 versus 10.5 +/- 3.4 ng/ml), although the respective plasma renin activity tended to be lower in diabetic patients than in control subjects (0.7 +/- 0.6 versus 1.3 +/- 0.9 and 1.8 +/- 1.8 versus 3.0 +/- 2.6 ng-1 . ml-1 . h-1).(ABSTRACT TRUNCATED AT 250 WORDS)

Purification and properties of a thiol protease from lung fluke adult Paragonimus ohirai

The thiol protease was purified from adult Paragonimus ohirai by alpha 1-antitrypsin-Sepharose, Sephadex G-75 and CM-cellulose, measuring its activities to hydrolyze hemoglobin and tosyl-L-lysine alpha-naphthyl-ester. The purified protease showed a single band on polyacrylamide disc gel isoelectrophoresis as zymogram with Tos-Lys-NE and also by protein staining, and its pI was found to be 6.4. The molecular weight was calculated to be 29,000 by gel filtration and 27,000 by SDS-polyacrylamide gel electrophoresis as a single polypeptide. The protease hydrolyzed hemoglobin and Tos-Lys-NE optimally at pH 4.0 and 5.0, respectively. The both hydrolyzing activities were inhibited by alpha 1-AT and soybean trypsin inhibitor as well as thiol protease inhibitors such as antipain, E-64 and p-hydroxymercuriphenylsulfonate. These results indicate that this enzyme is a new type thiol protease.

A comparative study of the measurement of urinary kallikrein by various methods in patients with essential hypertension and patients with proteinuria

In order to investigate the validity of urinary kallikrein (KAL) measurement, comparative studies were performed among the values obtained by various methods of urinary KAL measurements. Daily urine samples were collected from 37 hospitalized normal subjects (NS, 21 essential hypertensives without complications (EHT) and 20 patients with renal diseases associated with proteinuria (PU). Urinary KAL excretions were determined by direct radioimmunoassay (RIA), kininogenase assay (K-genase), TAMe esterase assay (TAMe), and PPA-MCA (MCA) and PPA-NE amidase assay (NE). By the desalting procedure, urinary KAL levels showed significant changes in TAMe, MCA and NE, but not in d-RIA and K-genase in all three groups. In TAMe, MCA and NE, the recovery of added KAL in urine was significantly lower in non-desalted samples in both EHT and PU, but not in NS. Impaired recovery and correlations between d-RIA or K-genase and TAMe, MCA or NE in non-desalted samples were improved by desalting. Although good correlations were observed between d-RIA or K-genase and TAMe, MCA or NE in desalted samples, the slopes of curves were steeper in EHT and PU than in NS, suggesting that the synthetic substrate methods still have some problems in the KAL measurement in these pathological states, KAL inhibitor, aprotinin and gabezate mesilate did not suppress the esterclytic and amidolytic activities completely, but suppressed K-genase activity completely in PU urine samples, suggesting that certain kinds of non-KAL esterases might remain in PU urine samples. Thus, d-RIA and K-genase appear to be the most reliable methods in the measurement of urinary KAL quantity and activity, respectively.

New synthetic substrate for kallikrein and its application

We developed a new synthetic substrate, Pro-Phe-Arg-alpha-naphthyl ester, for kallikrein. We found that this substrate had higher specificity and sensitivity for kallikrein and was applied for the preparation of zymogram and for the histochemical demonstration. With Pro-Phe-Arg-alpha-NE as substrate, the minimum detectable concentration of human urinary kallikrein was about 0.001 KU and then kallikrein could be determined with 25 microliter of human urine. We also found the possibility that occurring of abnormalities during pregnancy were predicted by the determination of urinary kallikrein of pregnants. Zymograms were prepared for various kinds of kallikrein using this substrate. The localization of kallikrein-like enzyme in rat kidneys was defined by the application this substrate for histochemistry. Moreover, cytochemical demonstrations of leucocytes in human blood were done using Ts-Lys-alpha-NE and Ac-Tyr-alpha-NE.

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."

Confirmation of direct angiotensin formation by kallikrein

This study was undertaken to confirm our previous preliminary observation that hog pancreas kallikrein (EC 3.4.21.35) directly liberated an angiotensin-like substance from human plasma protein Cohn fraction IV-4 at an acidic pH of 4.0-5.0. First, the possibility of proangiotensin or des-Asp1-angiotensin being the pressor substance was ruled out by t.l.c. Secondly, the pressor substance was purified by Sephadex G-25 and Bio-Gel P-2 gel filtration, and finally by high-performance liquid chromatography. The amino acid composition of the isolated pressor substance (residues/mol) was: Asp, 1.03; Val, 1.03; Ile, 1.00; Tyr, 0.69; Phe, 1.04; His, 0.91; Arg, 0.86; Pro, 0.86. This composition was identical with that of angiotensin. Since the reaction mixture was not contaminated with common proteolytic enzymes, such as trypsin, chymotrypsin, renin, cathepsin D and proangiotensin-converting enzyme, and other enzymes activated by kallikrein, it is clear that hog kallikrein directly produces angiotensin in vitro.

Role of glandular kallikrein in the activation process of human plasma inactive renin

Completely inactive renin was isolated from normal human plasma by DEAE-Sepharose column chromatography and Blue-Sepharose column chromatography. This inactive renin had a molecular weight of 54,000 daltons as determined by gel filtration on Ultrogel AcA 44. When the inactive renin was activated by trypsin, its molecular weight decreased to 48,000 daltons. The trypsin-activated renin differed from a native form of active renin in plasma with respect to molecular weight (active renin, 43,000), pI value (active renin, 5.20; trypsin-activated renin, 5.06), km value (active renin, 60 nmoles/liter; trypsin-activated renin, 89 nmoles/liter), Ki value for pepstatin A (active renin, 2.6 mumoles/liter; trypsin-activated renin 5.0 mumoles/liter) and pH profile for angiotensin formation. Glandular kallikrein (human urinary or pig pancreatic) did not activate the inactive renin. When the trypsin-activated renin was treated with glandular kallikrein, its activity was unchanged, but its molecular and kinetic properties except pI value (trypsin-activated kallikrein-treated renin, 4.82) coincided with those of a native form of active renin in plasma. These results indicate that glandular kallikrein does not directly activate inactive renin but participates in the activation process of inactive renin. The results also suggest that inactive renin in human plasma is a renin precursor.

A sensitive colorimetric assay for thrombin, prothrombin and antithrombin III in human plasma using a new synthetic substrate

Benzoyl-L-leucyl-L-alanyl-L-arginine-alpha-naphthylester (Bz-Leu-Ala-Arg-NE) was synthesized as a new substrate for use in the assay of thrombin. In the assay alpha-naphthol released by the enzyme reaction was measured colorimetrically. With Bz-Leu-Ala-Arg-NE as substrate, the minimum detectable concentration of human thrombin was 0.0025 U. This assay using Bz-Leu-Ala-Arg-NE is a highly sensitive method for detecting prothrombin, thrombin and antithrombin III in human plasma. Prothrombin could be determined with 0.2 microliter of human plasma using Echis carinatus venom (ECV) as activator. Antithrombin III activity could be determined with 2 microliter of human plasma using human thrombin and heparin as cofactor. A zymogram of human prothrombin was prepared with Bz-Leu-Ala-Arg-NE as substrate. The preparation gave one band (pI 4.9) on polyacrylamide disc gel isoelectrophoresis.

Histochemical localization of kallikrein-like Pro-Phe-Arg-naphthylester esterase activity in the rat kidney

In the rat kidney the presence of the kallikrein-like pro-phe-argnaphthylester esterase activity was demonstrated by a simultaneous coupling azo dye method. The enzyme was identified as a serine-protease because it was inhibited by preincubation with diisopropyl-fluorophosphate and unaffected by sodium iodoacetate. Since kallikrein is a serine-protease and prophe-arg-naphthylester is a synthetic and sensitive substrate for kallikrein, the enzyme activity revealed by this method was considered to represent kallikrein, although non-kallikrein esterase activity is not totally excluded. The enzyme activity was localized mainly in the outer stripe of the outer medulla, with focal extensions primarily only in the lower half of the cortex corresponding to the medullary rays.