Genealogy of mammalian cysteine proteinase inhibitors. Common evolutionary origin of stefins, cystatins and kininogens

A model for the evolution of mammalian cysteine proteinase inhibitors has been constructed on the basis of sequence homology. This model suggests that the diversity of cysteine proteinase inhibitors has evolved from two ancestral units forming the building blocks of stefin and cystatin. Gene triplication of the archetypal inhibitor generated the kininogen heavy chain which contains three cystatin-like copies. Hence, the superfamily of mammalian cysteine proteinase inhibitors is constituted by at least three distinct families, with stefin, cystatin and kininogen as their prototypes.

The ‘heavy’ subunit of the photosynthetic reaction centre from Rhodopseudomonas viridis : isolation of the gene, nucleotide and amino acid sequence

The gene coding for the ;heavy' subunit of the photosynthetic reaction centre from Rhodopseudomonas viridis was isolated in an expression vector. Expression of the heavy subunit in Escherichia coli was detected with antibodies raised against crystalline reaction centres. The entire subunit, and not a fusion protein, was expressed in E. coli. The protein coding region of the gene was sequenced and the amino acid sequence derived. Part of the amino acid sequence was confirmed by chemical sequence analysis of the protein. The heavy subunit consists of 258 amino acids and its mol. wt. is 28 345. It possesses one membrane-spanning alpha-helical segment, as was revealed by the concomitant X-ray structure analysis.

Limited proteolysis of human low-molecular-mass kininogen by tissue kallikrein. Isolation and characterization of the heavy and the light chains

The limited proteolysis of human low-molecular-mass kininogen by kallikrein from tissue sources has been studied. Porcine pancreatic kallikrein applied in catalytic amounts split the kininogen molecule (apparent mass 68 kDa) with the release of lysyl-bradykinin (1 kDa). This generated a nicked kininogen molecule with a heavy chain and light chain interconnected via disulfide bridging. Following reductive cleavage of the disulfide bonds, the heavy chain of apparent mass 62 kDa was isolated by preparative sodium dodecyl sulfate electrophoresis, and the light chain of 5 kDa by reversed-phase high-performance liquid chromatography. The light chain was found to be composed of 38 amino acids with a single half-cystine residue. Amino-terminal sequence analysis revealed that the light chain is derived from the carboxy terminus of the kininogen molecule [Lottspeich et al. (1984) Eur. J. Biochem. 142, 227-232]. Immunological characterization of the isolated L chain indicated that it harbours antigenic site(s) unique for low-Mr kininogen as well as sites common to high-Mr and low-Mr kininogen.

Human plasma kininogens are identical with alpha-cysteine proteinase inhibitors. Evidence from immunological, enzymological and sequence data

Human high- and low-Mr kininogens were shown to be potent inhibitors of cysteine proteinases such as cathepsin L and papain (Ki = 17-48 pM). A strong immunological cross-reaction between the kininogens and low-Mr alpha-cysteine proteinase inhibitor from human plasma was found. Comparison of partial amino acid sequences from high- and low-Mr kininogen and low-Mr alpha-cysteine proteinase inhibitor demonstrated sequence identity for all segments analyzed. These findings suggest that the kininogens and the alpha-cysteine proteinase inhibitors from human plasma are identical proteins.

The auricular myocardiocytes of the heart constitute an endocrine organ characterization of a porcine cardiac peptide hormone, cardiodilatin-126

A peptide hormone was extracted from the porcine right atrium following a bioassay for differential vasorelaxant effects on smooth muscle strips from aorta and renal and inferior mesenteric arteries. The isolation procedure included several steps of gel-permeation and ion-exchange chromatography, and high performance liquid chromatography. During the isolation procedure, other peptides of smaller molecular weight were also found, which, in relation to cardiodilatin-126 (CDD-126), are shorter at their N-terminal. Among these, CDD-88 has also been isolated and characterized, and has been established as a prominent member of the cardiac hormone family. The N-terminal and C-terminal segments of the 126 amino acid-containing molecule were synthesized and used to raise region-specific antibodies. The natural peptide was then localized within myoendocrine cells of the right atrium where specific atrial granules are located. Renal effects of cardiodilation were studied in conscious dogs and showed strong diuretic and natriuretic activities. According to our functional studies, cardiodilatin-126 and cardiodilatin-88 possess qualities of a significant hormone family regarding the regulation of extracellular fluid volume and blood pressure.

Human low-molecular-mass kininogen. Amino-acid sequence of the light chain; homology with other protein sequences

The complete amino acid sequence of the human low-molecular-mass kininogen light chain has been determined. The peptide chain contains 38 amino acid residues. In position 18 the half-cystine residue which forms the disulfide bridge to the heavy chain was found. Alignment of the present sequence with other kininogen light chain sequences indicated that the amino-terminal part of it is species-specific and the carboxy-terminal part is function-specific. Statistically significant internal homologies between various parts of the low-molecular-mass kininogen sequence as well as homologies between parts of the sequences of kininogen and ribonucleases were observed.

Boar acrosin is a two-chain molecule. Isolation and primary structure of the light chain; homology with the pro-part of other serine proteinases

Acrosin (EC 3.4.21.10), the major proteinase of mammalian spermatozoa, has been demonstrated to be a two-chain glycoprotein with an Mr-4200 light chain covalently attached to an Mr-37000 heavy chain. Following mercaptolysis of the disulfide bonds, the two chains were separated by high-performance liquid chromatography on a reversed-phase column. Sequence analysis of the isolated light chain (23 amino acid residues) indicated a considerable sequence homology with the bovine chymotrypsinogen activation peptide (6 out of 15 positions with identical amino acids, i.e. 40% identity) and the pro-part of other serine proteinases (17-22% identity), thus suggesting that the acrosin light chain corresponds to the pro-part of the acrosin zymogen. In position 3, the light chain confers a carbohydrate side chain N-glycosidically linked to the acceptor sequence Asn-Xaa-Thr. Evidence is presented that the acrosin light chain is connected via two disulfide bridges to the heavy chain which contains about 320 amino acids including the active-site residues of the proteinase.

Monoclonal anti-glycoprotein antibody that blocks cell adhesion in Polysphondylium pallidum

Polyclonal and monoclonal antibodies were prepared against a glycoprotein (gp 64) of Polysphondylium pallidum previously shown to act as a target site of adhesion-blocking Fab prepared from antisera against whole membranes of aggregation-competent cells. The purified glycoprotein, with a nominal Mr of 64000, could be fractionated into two subspecies, gp 64I and gp 64II, with apparent Mr of 66000 and 60000, as determined in 7.5% sodium dodecyl sulfate/polyacrylamide gels. Rabbit antibodies against purified gp 64 reacted not only with the two subspecies but also with many other membrane proteins. Almost all the cross-reactivity could be abolished by absorption of the antibodies with extensively purified gp 64. All monoclonal antibodies obtained by screening with gp 64 showed similar cross-reactivity. One monoclonal antibody specifically precipitating gp 64 was selected by screening with antigen that had been pretreated with anhydrous hydrogen fluoride for removal of carbohydrates. Fab from polyclonal anti-(gp 64) sera as well as one monoclonal Fab completely blocked cell adhesion of aggregation-competent P. pallidum cells. A carbohydrate fraction prepared by treatment of gp 64 with proteases and hydrazine completely neutralized the adhesion-blocking Fab. The product of hydrazinolysis contained less than 3% of the original peptide as based on the glucosamine recovered, but the specific neutralizing activity of the carbohydrate was essentially the same as that of the glycoprotein. In conclusion, monoclonal as well as polyclonal adhesion-blocking Fab reacted with carbohydrates; gp 64 shared the relevant carbohydrate moieties with other membrane proteins.

The right auricle of the heart is an endocrine organ. Cardiodilatin as a peptide hormone candidate

A new polypeptide hormone candidate regulating vascular smooth muscle function was extracted from porcine atrial tissue. The purification steps were followed by a bioassay. The hormonally active substance has been analyzed and found to be a small polypeptide exhibiting a molecular weight of about 7500 and is named "cardiodilatin" (CDD). Further chemical data on this new hormone will be published elsewhere. A partial amino acid sequence of cardiodilatin is offered and shows that among the well known hormones or neuropeptides, none exhibit a homologue partial sequence.

Hemocyanins in Spiders, XVIII. Complete amino-acid sequence of subunit e from Eurypelma californicum hemocyanin

The complete amino-acid sequence of subunit e of the hemocyanin from the tarantula, Eurypelma californicum, was determined by a combination of manual and automated methods. By limited proteolysis with chymotrypsin, two large fragments (e-CHn 29 and e-CHn 42) were obtained. The large peptides were further cleaved with cyanogen bromide, trypsin (with and without prior blocking of lysine residues), chymotrypsin, Staphylococcus aureus proteinase, Astacus fluviatilis proteinase, or 25% formic acid. The complete chain comprises 621 residues. A remarkable feature of the sequence is a hexapeptide -His-His-Trp-His-Trp-His- which is believed to take part in the binding of copper.

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.

Structural aspects of human kininogens

Kininogens have been purified from human plasma to apparent homogeneity. Native human LMW kininogen is a single-chain (glyco-) protein of molecular weight 68,000, which is converted to a two-chain protein by limited proteolysis with tissue kallikrein to form a heavy chain (Mr 62,000) and a light chain (Mr 4,000). Human HMW kininogen represents a single chain (glyco-)protein of Mr 114,000 which is split into two chains of similar size (H-chain of Mr 58,000 and L-chain of Mr 62,000) by limited proteolysis with tissue kallikrein. Sequence analysis of the isolated L-chain of human MW kininogen indicates a partial homology to the corresponding fragment-1.2 of bovine HMW kininogen. Purified kininogens readily form self-aggregates ranging from dimer to hexamer (HMW kininogen) and from dimer to decamer (LMW kininogen), respectively. Self-association is completely reversible in the presence of dissociating agents. Preliminary evidence suggests that oligomerisation is mediated by the H-chain common to the two types of kininogens.

Interaction of human alpha 1-proteinase inhibitor with chymotrypsinogen A and crystallization of a proteolytically modified alpha 1-proteinase inhibitor

Human alpha 1-proteinase inhibitor (alpha 1-PI) can form very stable complexes with chymotrypsinogen A or chymotrypsin if limited proteolysis by a contaminant proteinase is prevented with diisopropyl fluorophosphate. The contaminant proteinase cleaves the alpha 1-PI component in the alpha 1-PI-chymotrypsinogen A complex close to its N-terminus, between threonine-11 and aspartate-12 and the chymotrypsinogen A part between tyrosine-146 and threonine-147. By this modification the complex becomes unstable and dissociates into modified alpha 1-PI and neo-chymotrypsinogen A. A tritium labelling experiment shows that the contaminant proteinase is present in a 0.5-1.0% (w/w) ratio in the inhibitor preparation. These experiments indicate that alpha 1-PI is not a temporary inhibitor for these enzymes, as assumed by other authors. Isolated modified alpha 1-PI can be crystallized as tetragonal bipyramides from 2.6M sodium potassium phosphate pH 8.0. The crystals are suitable for three dimensional X-ray structure analysis. In spite of the cleavage of the susceptible peptide bond by chymotrypsinogen A, the C-terminal 3.6 kDa cleavage peptide remains tightly bound to the inhibitor by means of non-covalent interactions. In accordance with the result of the known complete amino-acid sequence of the inhibitor this finding offers an alternative explanation to the suggestion of alpha 1-PI being a double headed inhibitor. Isolated neo-chymotrypsinogen A can be activated to active chymotrypsin and can form a very labile 1 : 1 complex with alpha 1-PI, which dissociates rapidly into inactive inhibitor and neo-chymotrypsinogen.

Antinociceptive potencies of beta-casomorphin analogs as compared to their affinities towards mu and delta opiate receptor sites in brain and periphery

beta-Casomorphins and their analogs were tested for their opioid activities in the myenteric plexus longitudinal muscle preparation of the guinea pig ileum (GPI), the isolated mouse vas deferens (MVD), and for their affinities to mu- delta- and kappa- binding sites in rat brain membranes. C-terminal amidation of beta-casomorphin-4 and (-5) increased opioid potency in both organ preparations (GPI, MVD) and affinity to mu-binding sites in brain whereas binding to delta-sites was diminished. These beta-casomorphin-amides displayed a 2-3 times greater naloxone reversible antinociceptive effect than natural beta-casomorphins. Introduction of D-alanine at position 2 in the beta-casomorphin-amides increased potency in the GPI whereas activity in the MVD was only slightly changed. These compounds, however, showed a remarkable increase in binding to delta-sites in brain with an unaffected or slightly increased binding to mu-sites and decreased binding to kappa-sites. D-Ala2-beta-casomorphin-4 and (-5) amides were 10 times more potent antinociceptive agents than corresponding beta-casomorphin-amides. These results suggest firstly, that peripheral delta-receptors in the MVD are not as closely related to delta-binding sites at rat brain membranes as is the case with mu-receptors in the GPI and mu-binding sites, and secondly, in addition to mu-receptors, delta-receptors may be of importance in mediating antinociception.

Improved purification and N-terminal amino acid sequence determination of the contact site A glycoprotein of Dictyostelium discoideum

On aggregating cells of Dictyostelium discoideum a specific glycoprotein is expressed which is absent from growth phase cells of this organism. The glycoprotein has been related to cell surface antigens, called contact sites A, that are defined by their reaction with aggregation blocking antibody fragments. In the present paper an improved purification scheme for the glycoprotein is described and its N-terminal sequence is given. The purification has been monitored by use of a monoclonal antibody. The contact site A glycoprotein has the properties of an integral membrane protein.

Hemocyanins in spiders, XVII. A presumptive active-site sequence of arthropod hemocyanins

Peptides containing the sequence -His-His-Trp-His-Trp-His- have been isolated from the subunits e and a of tarantula (Eurypelma californicum) hemocyanin and III B of Limulus polyphemus hemocyanin. In view of the published spectroscopic and titration data on the copper-polypeptide complex and the strong quenching effect of oxygenation on hemocyanin fluorescence, it is concluded that this sequence represents the major part of the active site of Eurypelma, Limulus, and possibly other arthropod hemocyanins.

Analysis of human fibrinopeptides by high-performance liquid chromatography

During coagulation, fibrinogen is cleaved by thrombin, whereby fibrin and low molecular mass peptides, the so-called fibrinopeptides, are released. A novel method, employing high-performance liquid chromatography, has been developed for the separation and quantitation of these peptides. For the chromatography a reversed phase column was used. The fibrinopeptides were detected by their UV-absorption at 210 nm, peptides released from 0.1 mg of fibrinogen being easily detected. The procedure offers for the first time the possibility of determining all human fibrinopeptides and their degradation products in a single analysis. It is eminently suited for fibrinopeptide preparation and studies of fibrinopeptide release kinetics and genetically abnormal fibrinopeptides.

N-Terminal amino acid sequence of boar sperm acrosin. Homology with other serine proteinases

Boar acrosin with a molecular weight of 38,000 had been isolated. An N-terminal amino acid sequence of 52 residues was determined on the S-carboxymethylated material. The protein contains a single peptide chain. Up to 48% of the positions in the sequence show identity with those of some serine proteinases. The highest degree of homology was found at the comparison with plasmin and chymotrypsin. The N-terminus of acrosin corresponds to that of a serine proteinase in the activated form. The N-terminal amino acid is valine.

Identification of the phenylthiohydantoin derivatives of amino acids by high pressure liquid chromatography, using a ternary, isocratic solvent system

In recent years high-pressure liquid chromatography has found increasing application in protein chemistry for the identification of the phenylthiohydantoin derivatives of amino acids. For routine microsequencing none of the solvent systems so far published have proved ideal for this application. By using a ternary solvent system we have been able to achieve a rapid isocratic separation of the usual amino acid derivatives with the exception of the pair Gln greater than PhNCS/Ser greater than PhNCS. In practice discriminating between these two derivatives is seldom a problem because Gln greater than PhNCS is partially de-amidated during the conversion and is therefore always accompanied by Glu greater than PhNCS. The dependence of the retention times from pH, buffer composition, buffer concentration, and temperature will be discussed.