Primary structure of a hemorrhagic metalloproteinase, HT-2, isolated from the venom of Crotalus ruber ruber

Crotalidae and Viperidae snake venoms contains several kinds of metalloproteinases which cause localized hemorrhage by direct action on blood vessel walls. We report here the entire amino acid sequence and the disulfide bridge locations of HT-2, one of the hemorrhagic toxins isolated from the venom of Crotalus ruber ruber (red rattlesnake). The non-reduced protein was first cleaved at methionine residues to provide a set of 8 fragments, which covered the entire sequence of HT-2. The disulfide bridge locations of HT-2 were also determined by using these primary fragments. The unambiguous sequence for the whole protein was then established by conventional methods using lysyl endopeptidase and thermolysin digests. HT-2 consisted of 202 amino acid residues with two disulfide bridges, which were assigned to Cys-117-Cys-197 and Cys-157-Cys-164. HT-2 had a typical zinc-chelating sequence His-Glu-X-X-His (residues 142-146) found in thermolysin, and its overall sequence showed, respectively, 50, 52, and 53% identities to those of HR2a, H2-proteinase, and the metalloproteinase domain of HR1B. However, the disulfide bridge locations of HT-2 were different from those in the other metalloproteinases. The primary structure of HT-2 was more closely related to that of Ht-d from Crotalus atrox recently determined (81% identity). From the structural comparison with five metalloproteinases so far elucidated, six conservative amino acid residues, which may possibly be related to the induction of the hemorrhagic activity, were suggested to be present in these toxins.     

Two toxins from the venom of Trimeresurus tokarensis

1. Two toxins, Tokaratoxin-1 (TT-1) and Tokaratoxin-2 (TT-2), were isolated from the venom of Trimeresurus tokarensis using gel filtration on a Sephadex G-100 column, followed by chromatography on DEAE-Sephacel and carboxymethyl-cellulose. TT-1 possessed both hemorrhagic and proteolytic activities. However, TT-2 did not show hemorrhagic activity. 2. Homogeneity was established by the formation of a single band in acrylamide gel electrophoresis, isoelectric focusing and SDS-PAGE. 3. Molecular weights of TT-1 and TT-2 were 71,000 and 25,400, respectively. Although TT-2 is a basic protein, TT-1 is an acidic protein. 4. Biological activities of TT-1 and TT-2 were inhibited by EDTA, EGTA and o-phenanthroline, suggesting that the toxins are metalloproteins. Atomic absorption analyses indicated that TT-1 contains 2.79 mol Ca/mol protein and TT-2 contains 1.04 mol Ca/mol protein and 1.07 mol Zn/mol protein, respectively. 5. The two toxins degraded the A alpha and B beta chains of fibrinogen. 6. TT-1 induced necrosis in addition to its hemorrhagic activity while TT-2 induced necrosis only.     

Purification and biochemical characterization of atroxase, a nonhemorrhagic fibrinolytic protease from western diamondback rattlesnake venom

Crotalus atrox venom contains a variety of proteases which render fibrinogen incoagulable and solubilize fibrin. One of these proteases was purified by using ion-exchange and gel permeation liquid chromatography. The protease, called atroxase, consists of a single nonglycosylated polypeptide chain with a molecular weight of 23,500 and an isoelectric point of pH 9.6. Amino acid analysis indicates atroxase to contain 206 residues with no sulfhydryl groups. Metal analysis found zinc and potassium at 1 mol/mol of protein, and calcium at 0.3 mol/mol of protein. Proteolytic activity is inhibited by ethylenediaminetetraacetate and alpha 2-macroglobulin. Maximal proteolytic activity occurs at pH 9.0 and 55 degrees C. Proteolytic specificity, using oxidized insulin B chain, is similar to that of several hemorrhagic toxins found within the same venom, yet atroxase shows no hemorrhagic activity and exhibits low lethality when tested on Swiss Webster mice. Atroxase, an A alpha, B beta fibrinogenase, cleaves the A alpha chain of fibrinogen first followed by the B beta chain and shows no effect on the gamma chain. The nonspecific action of the enzyme results in the extensive hydrolysis of fibrinogen which releases a variety of fibrinopeptides. Fibrin solubilization appears to occur primarily from the hydrolysis of alpha-polymer and unpolymerized alpha and beta chains. Although crude venom induces platelet aggregation, atroxase demonstrated no ability to induce or inhibit aggregation.     

湖南尖吻蝮蛇毒两个出血毒素的纯化和理化性质

经ＳｅｐｈａｄｅｘＧ－７５凝胶过滤,ＱＡＥ－ＳｅｐｈａｄｅｘＡ－５０和ＣＭ－ＳｅｐｈａｄｅｘＣ－２５离子交换层析的步骤,从湖南产尖吻蝮（Ｄｉｅｎａｇｋｉｓｔｒｏｄｏｎａｃｕｔｕｓ）蛇毒中纯化出两个出血毒素（ＤａＨＴ－１和ＤａＨＴ－２）．ＳＤＳ－ＰＡＧＥ测得分子量均为２３．５ｋＤ,ＩＥＦ－ＰＡＧＥ测得等电点分别为５．６和５．２,两者具有相似的氨基酸组成,其中酸性氨基酸（Ａｓｘ,Ｇｌｘ）分别占２３％和２４％,ＤａＨＴ－１和ＤａＨＴ－２的最小出血剂量（ＭＨＤ）分别为０．５μｇ和０．８μｇ。都具蛋白水解酶活性,无对ＴＡＭＥ,ＢＡＥＥ的水解活性和ＰＬＡ２酶活性．两者的蛋白水解酶活力与出血活性并非正相关．ＤａＨＴ－１和ＤａＨＴ－２的最适温度分别为３５℃和４０℃,最适ｐＨ为６－９,对热均不稳定,温度高于６０℃活性完全丧失。金属离子的分析显示每摩尔毒素蛋白约含０．５ｍｏｌ的Ｚｎ,１ｍｏｌ的Ｃａ,较多的Ｎａ、Ｋ、Ｍｇ,不含Ｃｏ。     

Presence of zinc in proteolytic hemorrhagic toxin isolated from Agkistrodon acutus venom

1. Hemorrhagic toxin (Ac1-proteinase) was isolated from the venom of Agkistrodon acutus (Formosa) and the zinc content was determined (1.15 mol/mol protein). The results we extensively compared with hemorrhagic toxin e of Crotalus atrox venom (U.S.A.). Comparable results were obtained for zinc content, hemorrhagic and proteolytic activities for native hemorrhagic toxins from two different venoms. It is of interest that the zinc content of hemorrhagic toxins is identical even though the venoms are obtained from snakes inhabiting totally different continents. 2. Zinc content, hemorrhagic and proteolytic activities were compared before and after the removal of zinc. It was found that both hemorrhagic and proteolytic activities disappeared upon removal of the zinc. 3. Zinc content of all hemorrhagic toxins with proteolytic activity reported so far were also compared and it is concluded that regardless of their geographic origin, zinc is present in venom hemorrhagic toxins on a unimolar basis. 4. When zinc is removed there is a drastic change in the low-frequency region of the Raman spectrum suggesting the presence of a zinc ligand co-ordination. The decrease of alpha-helical content and increase of random coil are reflected in the amide I and III bands of Raman spectroscopy after the removal of zinc. Increase of random coil and the loss of zinc are probably responsible for the loss of hemorrhagic and proteolytic activities.     

Isolation and biochemical characterization of hemorrhagic toxin f from the venom of Crotalus atrox (western diamondback rattlesnake)

Hemorrhagic toxin f (HT-f) was isolated from Crotalus atrox (Western Diamondback Rattlesnake) venom by a five-step purification procedure. Homogeneity was established by the formation of a single band in acrylamide gel electrophoresis, isoelectric focusing, and sodium dodecyl sulfate (SDS)-electrophoresis. HT-f has a molecular weight of 64,000 and contains 572 amino acid residues. It contains 1 mol of zinc per mol of protein. Zinc is essential for both hemorrhagic and proteolytic activities. HT-f possesses proteolytic activity hydrolyzing the Val-Asn, Gln-His, Leu-Cys, His-Leu, Ala-Leu, and Tyr-Leu bonds of oxidized insulin B chain. HT-f did not coagulate fibrinogen to fibrin, yet it did hydrolyze the gamma chain of fibrinogen without affecting either the A alpha or B beta chains. This is the first time that a hemorrhagic toxin was shown to have fibrinogenase activity. HT-f was shown to differ immunologically from other hemorrhagic toxins such as HT-a and HT-c. HT-f also possesses lethal toxicity. When zinc was removed the apo-HT-f lost its lethal toxicity. HT-f produced not only local hemorrhage in the skin and muscle, but also produced systemic hemorrhage in internal organs such as the intestine, kidney, lung, heart, and liver.     

Hemorrhagic toxins from Western diamondback rattlesnake (Crotalus atrox) venom: isolation and characterization of five toxins and the role of zinc in hemorrhagic toxin e.

Five previously unknown hemorrhagic proteins, designated hemorrhagic toxins a,b,c,d, and e, were isolated from the venom of the western diamondback rattlesnake (Crotalus atrox). Molecular weights of hemorrhagic toxins a-e were determined to be 68 000, 24 000, 24 000, 24 000, and 25 700, respectively, by sodium dodecyl sulfate-phosphate gel electrophoresis using various polyacrylamide gel concentrations. Amino acid composition showed a total of 636, 200, 213, 214, and 219 amino acids for hemorrhagic toxins a-e, respectively. All the hemorrhagic toxins were found to lose their hemorrhagic activities with the metal chelators ethylenediaminetetraacetic acid and 1, 10-phenanthroline. All the hemorrhagic toxins were found to contain approximately 1 mol of zinc/mol of toxin, and they were all demonstrated to be proteolytic when dimethylcasein and dimethylhemoglobin were used as substrates. When zinc was removed from hemorrhagic toxin e with 1,10-phenanthroline, both both the proteolytic and hemorrhagic activities were equally inhibited. When the apohemorrhagic toxin e thus produced was incubated with zinc, the hemorrhagic and proteolytic activities were regenerated to the same extent. CD, UV, and Raman spectroscopy were used to study the structure of native hemorrhagin toxin e as well as the structural changes caused by zinc removal. From CD spectroscopy the native toxin was estimated to consist of 23% alpha helix, 6% beta structure, and 71% random-coil conformation. When over 90% of the zinc was removed, the alpha-helix content dropped from 23 to 7%.     

Phosphodiesterase from the venom of Crotalus ruber ruber

Phosphodiesterase was isolated from the venom of Crotalus ruber ruber from the U.S.A. using the gel filtration on a Sephadex G-75 column, followed by anion or cation exchange chromatography. Phosphodiesterase was homogeneous as established by a single band on acrylamide gel electrophoresis and isoelectric focusing electrophoresis. Phosphodiesterase activity was inhibited by ethylenediamine tetraacetic acid (EDTA), o-phenanthroline, thioglycolic acid or p-chloromercuribenzoate (PCMB), but not by soybean trypsin inhibitor (SBTI) or benzamidine. The molecular weight of this enzyme was determined to be approx. 98,000 and the isoelectric point was found to be pH 10.5 by isoelectric focusing with carrier ampholyte. This enzyme contained 1.04 mol zinc per mol. The Michaelis constant (Km) of this enzyme for p-nitrophenyl thymidine-5'-phosphate and inhibition constant (Ki) for PCMB were found to be 8.3 X 10(-3) and 1.2 X 10(-2) M, respectively.     

Characterization of kallikrein-like enzyme from Crotalus ruber ruber (red rattlesnake) venom

1. A kallikrein-like enzyme from the venom of Crotalus ruber ruber (red rattlesnake) had been isolated and characterized by Mori and Sugihara. The enzyme was active upon the kallikrein substrates, Pro-Phe-Arg-MCA and z-Phe-Arg-MCA, and slightly hydrolyzed Boc-Val-Leu-Lys-MCA, and Boc-Phe-Ser-Arg-MCA. 2. Unlike thrombin, the newly isolated kallikrein-like enzyme did not cause formation of a fibrin clot when fibrinogen was mixed with the enzyme. 3. The B beta chain of fibrinogen was first split and A alpha chain was cleaved later. Pancreatic kallikrein hydrolyzed only the A alpha chain without affecting the B beta chain. 4. The kallikrein-like enzyme produced kallidin (Lys-bradykinin) by splitting the Met-Lys bond instead of producing bradykinin. 5. The kallikrein analog JSI-450 (Ac-Phe-Ser-Pro-Phe-Arg-Ser-Val-Gln-Val-Ser-NH2) was also cleaved at the site of the Arg-Ser bond. 6. Its NH2-terminal amino acid sequence (Val-Ile-Gly-Gly-Asp-Glu-Cys-Asn-Ile-Asn-Glu-Arg-Pro-Phe-Leu-Val-Ala-Leu-Tyr- Asp-Ser-) is homologous to the rat pancreatic kallikrein and other snake venom proteases.     

Hemorrhagic toxin from the venom of Agkistrodon bilineatus (common cantil)

1. Hemorrhagic toxin was isolated from Agkistrodon bilineatus (Common cantil) venom using a three-step purification procedure to obtain 32.8 mg of purified hemorrhagic toxin from 700 mg of crude venom. 2. The purified toxin was homogeneous by disc polyacrylamide gel electrophoresis at pH 8.3, and by isoelectric focusing. 3. Hemorrhagic toxin possessed lethal, hemorrhagic and proteolytic activities. These activities of this toxin were inhibited by ethylenediaminetetraacetic acid (EDTA) and ethyleneglycol-bis-(beta-aminoethylether)N,N'-tetraacetic acid (EGTA), but not by cysteine or soybean trypsin inhibitor (SBTI). 4. Its molecular weight was approximately 48 kDa and the isoelectric point was 4.2. 5. Purified preparation hydrolyzed the Asn(3)--Gln(4), His(10)--Leu(11), Ala(14)--Leu(15), Tyr(16)--Leu(17), Arg(22)--Gly(23) and Phe(24)--Phe(25) bonds of oxidized insulin B. chain. 6. The A alpha chain of fibrinogen was first split and B beta chain was cleaved later by this toxin. 7. Hemorrhagic toxin contains 1 mol of zinc and 2 mol of calcium per mol of protein.     

Comparative study of two arginine ester hydrolases, E-I and E-II from the venom of Crotalus ruber ruber (red rattlesnake)

1. Two arginine ester hydrolases, E-I and E-II from the venom of Crotalus ruber ruber were isolated and characterized. 2. E-I and E-II have molecular weights of 32,000 and 33,000, and isoelectric points of 5.2 and 4.6, respectively. 3. E-I and E-II are active upon the glandular kallikrein substrate, but neither enzyme was shown to have plasma kallikrein substrate hydrolytic activity. 4. E-I has minimal fibrinogen-clotting activity. It was found to induce clotting by catalyzing the hydrolysis of only the A fibrinopeptide from the A alpha-chain of fibrinogen.     

Isolation of two hemorrhagic toxins from Crotalus basiliscus basiliscus (Mexican west coast rattlesnake) venom and their effect on blood clotting and complement

1. Two hemorrhagic toxins of mol. wt 27,000 (B1) and 27,500 (B2) and pI 9.8 and 5.2 respectively were isolated from Crotalus basiliscus venom. 2. The two proteinases did not cross-react antigenically. 3. Both toxins caused hemorrhage in mice and each was capable of hydrolyzing hide power azure, casein, collagen and fibrin. 4. B1 hydrolyzed the A alpha, B beta and gamma chains of fibrinogen. B2 hydrolyzed the A alpha and B beta chains of fibrinogen, but not the gamma chain. 5. Both proteinases inactivated guinea pig complement.     

Purification and characterization of the hemorrhagic factor II from the venom of the Bushmaster snake (Lachesis muta muta)

Hemorrhagic factor II (LHF-II) was isolated from Lachesis muta muta (Bushmaster snake) venom using column chromatographies on Sephadex G-100, CM-Sepharose CL-6B and two cycles on Sephadex G-50. This preparation was devoid of phospholipase A2 as well as of the enzymes active on arginine synthetic substrates (TAME and BAPNA) which are present in the crude venom. LHF-II was homogeneous by SDS-polyacrylamide gel electrophoresis, immunodiffusion and immunoelectrophoresis. Also, a single symmetrical boundary with a value of 2.59 S was obtained by ultracentrifugation. LHF-II contains 180 amino acid residues, has a molecular weight of 22,300, and an isoelectric point of 6.6. It contains one gatom zinc and two gatoms calcium per mol protein. The hemorrhagic factor possesses proteolytic activity toward various substrates such as, casein, dimethylcasein, hide powder azure, fibrinogen and fibrin. It hydrolyzes selectively the A alpha-chain of fibrinogen, leaving the B beta- and gamma-chains unaffected. LHF-II is activated by Ca2+ and inhibited by Zn2+. The hemorrhagic as well as the proteinase activity is inhibited by cysteine and by metal chelators such as EDTA, EGTA and 1,10-phenanthroline. Inhibitors of serine proteinases such as phenylmethanesulfonyl fluoride (PMSF) and soybean trypsin inhibitor (SBTI) have no effect on the hemorrhagic factor.     

Kallikrein-like enzyme from Crotalus ruber ruber (red rattlesnake) venom

1. A kallikrein-like enzyme was isolated and characterized from the venom of Crotalus ruber ruber (red rattlesnake). 2. The kallikrein-like enzyme was shown to be homogeneous as demonstrated by a single band on acrylamide gel electrophoresis, isoelectric focusing, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, immunodiffusion and reverse-phase (RP) HPLC. 3. The enzyme has a molecular weight of 31,000 and isoelectric point of 4.6. It consists of 271 total amino acid residues, 24% of which are acidic amino acids. 4. Specific esterolytic activities of the kallikrein-like enzyme on N-tosyl-L-arginine methylester (TAME) and N-benzoyl-L-arginine ethylester (BAEE) are 109.5 and 23.6 mumol/min/mg, respectively. 5. The enzyme differs from trypsin as the soybean trypsin inhibitor does not inhibit the enzyme's action. Diisopropylfluorophosphate (DFP) inhibits the enzyme, suggesting that the serine hydroxyl group is important for enzyme activity. 6. The enzyme is not lethal at 15 micrograms/g in mice and has no hemorrhagic activity, yet the injection of the purified enzyme intradermally, produced capillary permeability-increasing activity as shown by the use of Evans blue dye, and immediate drop in blood pressure. It also contracted the rat uterus.     

红色红曲菌蛋白质组双向凝胶电泳体系的建立

红曲菌是一种具有较高食用和药用价值的丝状真菌,能够产生红曲色素、莫纳可林K等多种生理活性物质。通过分析比较培养基、蛋白质裂解液组成以及水化上样条件对双向电泳结果的影响,建立了红色红曲菌蛋白质组的双向凝胶电泳体系,为从蛋白质水平研究红曲菌及其次级代谢产物的生物合成提供依据。结果表明：用YES培养基培养红色红曲菌6 d,TCA 丙酮法提取菌体总蛋白质,蛋白质裂解液组分为8mol/L尿素,2mol/L硫脲,4 % CHAPS,1 % DTT和2 % Bio-lyte,可获得蛋白质样点数量多,清晰度高的双向电泳图像,为进一步研究红曲菌蛋白质组奠定了基础。     

Purification and characterization of a fibrinogenolytic and hemorrhagic metalloproteinase isolated from Vipera lebetina venom

Serious clinical problems such as hemorrhage, edema and tissue necrosis are observed following viperid envenoming. A proteinase (VLH2) was isolated from Vipera lebetina by combination of two chromatographic steps of gel filtration on Sephadex G-75 followed by DEAE Sephadex A-50. This acidic proteinase, with a molecular mass of about 55 kDa and isoelectric point of 5.4, displayed a fibrinogenolytic and hemorrhagic activities. VLH2 hydrolyses rapidly the Aα-chain of fibrinogen, followed, more slowly, by the Bβ-chain, leaving the γ-chain unaffected. The proteolytic and hemorrhagic activities of VLH2 were inhibited by EDTA, EGTA and 1–10 phenanthroline. However, these activities were not affected by AEBSF, Aprotinine, and E64, suggesting that VLH2 is a metalloproteinase with an α-fibrinogenase activity, requiring calcium and zinc for its activity. The enzyme VLH2 did not have proteolytic activity towards extracellular components gelatin, laminin and fibronectin. The hemorrhagic metalloproteinase VLH2 has a myotoxic activity, as determined by serum CK level and histological observation of muscle tissue. Furthermore, VLH2 is able to induce apoptosis of C2C12 myotubes. These results indicate that VLH2 is implicated in the local and systemic bleeding, contributing thus in the toxicity of V. lebetina venom.     

Isolation of a human plasmin-derived, functionally active, light (B) chain capable of forming with streptokinase an equimolar light (B) chain-streptokinase complex with plasminogen activator activity.

A functionally active human plasmin light (B) chain derivative, stabilized by the streptomyces plasmin inhibitor leupeptin, was isolated from a partially reduced and alkylated enzyme preparation by an affinity chromatography method with a L-lysine-substituted Sepharose column. This light (B) chain derivative was found to be relatively homogeneous by electrophoretic analysis in both an acrylamide gel/dodecyl sulfate system and on cellulose acetate. It possessed approximately 3% of the proteolytic activity (casein substrate) of the original enzyme, and it incorporated 0.09 mol of [3H]diisopropyl phosphorofluoridate per mol of protein. It contained 3.1 +/- 0.3 carboxymethylated cysteines per mol of protein and can be designated as a CmCys5-light (B) chain (CmCys)3. When this isolated light (B) chain derivative was mixed in equal molar amounts with streptokinase, the mixture developed both human and bovine plasminogen activator activities; the bovine activator activity was approximately 66% of the bovine activator activity of the equimolar human plasmin-streptokinase complex. Although this complex now incorporated 0.50 mol of [3H]diisopropyl phosphorofluoridate per mol of protein, its proteolytic activity, on a molar basis, was the same as the proteolytic activity of the isolated light (B) chain derivative. It was shown by electrophoretic analysis in both an acrylamide gel/epsilon-aminocaproic acid system and on cellulose acetate that the light (B) chain derivative and streptokinase forms an equimolar light (B) chain-streptokinase complex, indicating that the binding site for streptokinase is located on the light (B) chain of the enzyme. A functionally active equimolar light (B) chain-streptokinase complex was also isolated from a partially reduced and alkylated equimolar human plasmin-streptokinase complex by the affinity chromatography method. The plasminogen activator activities (human and bovine) of this light (B) chain-streptokinase complex were similar to those of the plasmin-streptokinase complex from which it was derived. Although this complex incorporated 0.70 mol of [3H]diisopropyl phosphorofluoridate per mol of protein, its proteolytic activity, on a molar basis, was only 14% of proteolytic activity of the plasmin-streptokinase complex.     

North-south regional variation in phospholipase A activity in the venom of Crotalus ruber.

1. Twenty-seven individual venoms from the rattlesnake species Crotalus ruber from different regions were comparatively analyzed by reverse-phase HPLC and analyzed for phospholipase A (PLA) content using a polarographic assay. 2. Two fractions containing PLA activity were detected by HPLC in the venoms of all the C. ruber specimens from southern Baja, Mexico, but specimens from southern California, U.S.A., were lacking corresponding fractions and were extremely low or lacking in PLA activity in their venoms. 3. The north-south regional variation in PLA content in C. ruber venom does not correlate with the north-south ranges (based on external morphology) of the subspecies C. ruber ruber and C. ruber lucasensis.     

Preparative isolation of lipid inclusions from Rhodococcus opacus and Rhodococcus ruber and identification of granule-associated proteins

Triacylglycerol granules synthesized and accumulated by Rhodococcus opacus and Rhodococcus ruber were isolated by glycerol density gradient centrifugation. Whereas only one type of granule could be isolated from R. opacus, two types of granules with different specific densities were isolated from R. ruber. Both types of R. ruber granules showed a similar content of triacylglycerols and poly(3-hydroxybutyrate- co-3-hydroxyvalerate), but the protein profiles of both types were significantly different. The granules with the lower specific density were colorless; the granules with the higher specific density had a deep orange pigmentation. Solubilization studies revealed three different groups of granule-associated proteins: (1) unspecifically bound proteins, (2) relatively weakly associated proteins, and (3) proteins that resisted solubilization by treatment with 2 M NaCl, 2% (w/v) Triton X-114, 6 M guanidinium hydrochloride, up to 8% (w/v) SDS, and proteolytic digestion. The strong association of proteins of the last group suggested that these may play a specific role in the synthesis or mobilization of storage lipids or in the structure of the granules. The N-terminal amino acid sequences of the most tightly bound proteins were obtained. Proteins of low molecular weight with striking sequence similarity to the ribosomal protein L7 from various actinomycetes were always copurified with the granules.     

Efficient production and processing of elastase and LasA by Pseudomonas aeruginosa require zinc and calcium ions.

The ability of Pseudomonas aeruginosa to degrade elastin, a major component of connective tissue, likely contributes to its pathogenicity and multiplication in human tissues. Two extracellular enzymes are required for P. aeruginosa elastolytic activity: elastase and LasA. Elastase is a zinc metalloprotease, but little is known about the structure of LasA. When grown under metal ion-deficient conditions, P. aeruginosa culture supernatants were found to exhibit a low level of elastolytic activity, which coincided with production of low levels of the 51-kDa proelastase and no detectable LasA. By using this fact to identify factors that promote elastolytic activity, P. aeruginosa PAO1, FRD2, and DG1 were grown in metal ion-deficient medium supplemented with zinc (10(-4) M ZnCl2), calcium (2.5 x 10(-3) M CaCl2), or iron (10(-4) M FeCl3). High levels of proteolytic and elastolytic activity were exhibited by all strains when cultured in the presence of both zinc and calcium, and this was associated with the production of mature 33-kDa elastase and 21-kDa LasA. Supplementing DG1 and PAO1 cultures with zinc alone stimulated the production of 33-kDa elastase, which, because of the calcium-deficient conditions, exhibited low proteolytic and elastolytic activities. Zinc also stimulated the production of a 41-kDa form of LasA in DG1 and PAO1 culture supernatants. Elastase production by FRD2 cultured in the presence of zinc alone differed from that by the other two strains in that supernatants contained 33-kDa elastase, a 21-kDa form of LasA, and exhibited high proteolytic and elastolytic activities. Such strain-associated differences in LasA processing and elastase activity can be explained by differences in metal ion-scavenging mechanisms adapted by the strains. Supplementing cultures with calcium stimulated the production of elastase but had no effect on LasA production. The elastase produced exhibited variable sizes, possibly resulting from aberrant processing reactions, and showed little proteolytic activity. Proteolytic activity could be recovered from 33-kDa elastase produced in the presence of calcium by inclusion of zinc in the enzymatic assay. Although iron was previously found to exert a repressive effect on P. aeruginosa elastolytic activity, iron exerted little effect on elastolytic activity when added to cultures containing both zinc and calcium. These studies support the conclusion that elastase production and processing are promoted by both zinc and calcium. LasA production, in comparison, is stimulated by zinc, with both zinc and calcium facilitating its processing. The association of 41-kDa LasA with a low level of elastolytic activity and of 21-kDa LasA with a high level of activity supports the conclusion that lasA encodes a larger, precursor protein which is processed to an active 21-kDa form during secretion.