Isolation and characterization of sheep alpha 1-proteinase inhibitor

Purification and partial characterization of α1-proteinase inhibitor in the common marmoset (Callithrix jacchus)

Fecal alpha1-proteinase inhibitor (α1-PI) concentration has been to diagnose enteric protein loss in dogs and cats. Chronic lymphocytic enteritis is commonly seen in the marmoset (Callithrix jaccus) and is characterized by hypoalbuminemia. As a prelude to immunoassay development for detecting enteric protein loss, marmoset serum α1-PI was purified using immunoaffinity chromatography and ceramic hydroxyapatite chromatography. Partial characterization was performed by reducing gel electrophoresis and enzyme inhibitory assays. Protein identity was confirmed with peptide mass fingerprinting and N-terminal amino acid sequencing. Molecular mass, relative molecular mass, and isoelectric point for marmoset α1-PI were 54 kDa, 51,677, and 4.8-5.4, respectively. Trypsin, chymotrypsin, and elastase inhibitory activity were observed. N-terminal amino acid sequence for marmoset α1-PI was EDPQGDAAQKMDTSHH. In conclusion, marmoset α1-PI was successfully purified from serum with an overall yield of 12% using a rapid and efficient method. Purified marmoset α1-PI has characteristics similar to those of α1-PI reported for other species.

Purification and biochemical characterization of ovine alpha-1-proteinase inhibitor: mechanistic adaptations and role of Phe350 and Met356

The glycoprotein alpha-1-proteinase inhibitor (alpha-1-PI) is a member of the serpin super family that causes rapid and irreversible inhibition of redundant serine protease activity. A homogenous preparation of ovine alpha-1-PI, a 60 kDa protein was obtained by serially subjecting ovine serum to 40-70% (NH(4))(2)SO(4) precipitation, Blue Sepharose, size-exclusion, and concanavalin-A chromatography. Extensive insights into the trypsin, chymotrypsin, and elastase interaction with ovine alpha-1-PI, point towards the involvement of Phe(350) besides the largely conserved Met(356) in serine protease recognition and consequent inhibition. The N-terminal of C-terminal peptides cleaved on interaction with elastase, trypsin, and chymotrypsin prove the presence of diffused sub-sites in the vicinity of Met(356) and the strategically positioned Pro anchored peptide stretch. Further, human alpha-1-PI is more thermolabile compared to ovine alpha-1-PI, higher thermolability is mainly attributed to poorer glycosylation. The enzymatic deglycosylation of human and ovine alpha-1-PI results in diminished thermostability of the inhibitors, with sharp decrease in thermal transition temperatures but retaining their inhibitory potency. Homology modeling of the deduced amino acid sequence of ovine alpha-1-PI using the human alpha-1-PI template has been used to explain the observed inhibitor-protease interactions.

Identification of sperm forward motility-related proteins in human seminal plasma

Seminal plasma, an amorphous material that exists in semen, contains proteins related to sperm forward motility. Employing affinity chromatography with ConA beads and protein ultrafiltration, we isolated and concentrated proteins from heated human seminal plasma. Results of computer-assisted semen analyses (CASA) demonstrated that the forward motility index of bovine spermatozoa from the epididymal caput, incubated with proteins and theophylline, was significantly different from that of spermatozoa incubated with theophylline alone (P < 0.01). The electrophoreses revealed that the protein bands with high molecular weights in the gel of PAGE changed into low molecular weights in the gel of SDS-PAGE. Furthermore, proteins from a separated portion of the PAGE gel were still able to stimulate spermatozoa from the epididymal caput to gain forward motility. Two-dimensional (2D)-gel electrophoresis and mass spectrometry indicated that spots focused on the portion seemed, according to their amino acid sequences, to be like human alpha-1-antitrypsin and zinc-alpha-2-glycoprotein (ZAG) precursors. Western blot analysis showed the presence of these two proteins in seminal plasma. These proteins, related to the forward motility of spermatozoa in human seminal plasma, may play important roles during maturation of spermatozoa, from the epididymis through fertilization in the female reproductive tract.

Purification and partial characterization of feline α1-proteinase inhibitor (fα1-PI) and the development and validation of a radioimmunoassay for the measurement of fα1-PI in serum

Alpha(1)-proteinase inhibitor (alpha(1)-PI) of the domestic cat (Felis catus) was purified from serum and a radioimmunoassay (RIA) for the measurement of feline alpha(1)-PI concentration in serum was developed and validated. Feline alpha(1)-PI (falpha(1)-PI) was isolated using ammonium sulfate precipitation, anion-exchange, size-exclusion, ceramic hydroxyapatite, and hydrophobic interaction chromatography. The molecular weight of falpha(1)-PI was estimated at 57,000 and the relative molecular mass (M(r)) was determined to be approximately 54.5 kDa. Isoelectric focusing revealed four bands with isoelectric points (pI) between 4.3 and 4.5. The N-terminal amino acid sequence of the first 19 residues was Glu-Gly-Leu-Gln-Gly-Ala-Ala-Val-Gln-Glu-Thr-Val-Ala-Ser-Gln-His-Asp-Gln-Glu. Antiserum against feline alpha(1)-PI was raised in rabbits. Tracer was produced by iodination ((125)I) of feline alpha(1)-PI using the chloramine T method. A radioimmunoassay was established and validated by determination of sensitivity, dilutional parallelism, spiking recovery, intra-assay variability, and inter-assay variability. A control range for serum feline alpha(1)-PI concentration was established from 50 healthy cats using the central 95th percentile. The sensitivity of the assay was 0.042 mg/ml. Observed to expected ratios for serial dilutions ranged from 105% to 141.18% for four different serum samples at dilutions of 1 in 35,000, 1 in 70,000, 1 in 140,000 and 1 in 280,000. Observed to expected ratios for spiking recovery ranged from 88.14% to 152.17% for four different serum samples and five different spiking concentrations. Coefficients of variation for four different serum samples were 4.57%, 6.45%, 8.52%, and 4.27% for intra-assay variability and 6.88%, 9.57%, 7.44%, and 9.94% for inter-assay variability. The reference range was established as 0.25-0.6 mg/ml. In summary, feline alpha(1)-PI was successfully purified from serum using a rapid and efficient method. The radioimmunoassay described here is sensitive, linear, accurate, precise, and reproducible and will facilitate further studies of the physiological or potential pathological role of alpha(1)-PI in cats.

Purification and N-terminal amino acid sequence of sheep neutrophil cathepsin G and elastase

Sheep cathepsin G (CG) and neutrophil elastase (NE) were isolated from a crude leukocyte membrane preparation by elastin-Sepharose 4B and CM-Sepharose 4B chromatography, followed by native preparative PAGE. The N-termini of CG and NE were sequenced to 24 and 20 residues, showing 96 and 85% identity with human CG and NE, respectively. During SDS-PAGE, sheep CG and NE migrated parallel to human CG and NE and have apparent molecular masses of 28 and 26 kDa, respectively. Following incubation of sheep CG and NE with human alpha(1)-antichymotrypsin and alpha(1)-proteinase inhibitor, complexes with apparent molecular masses of 89 and 81 kDa respectively were observed by SDS-PAGE. Polyclonal antibodies to human CG and NE cross-reacted with purified sheep CG and NE, respectively. These results indicate that sheep neutrophils contain CG and elastase that are analogous to human CG and NE in terms of molecular mass, reactivity with endogenous inhibitors, immunocross-reactivity, and N-terminal sequence.

Purification and characterization of a novel Kazal-type serine proteinase inhibitor of neutrophil elastase from sheep lung

A Kazal-type elastase inhibitor was purified by trichloroacetic acid precipitation of sheep lung lavage fluid followed by chymotrypsin affinity and gel-filtration chromatography of the supernatant. Sheep lung elastase inhibitor (SLEI) is glycosylated. Laser desorption mass spectrometry indicated that SLEI has a molecular mass of 16.8-17.3 kDa. Partial protein sequence of SLEI and of a peptide derived from SLEI showed 31-52% and 51-66% homology at the N-terminus and at the inhibitory site respectively with Kazal-type double-headed proteinase inhibitors (bikazins). SLEI inhibited human leukocyte elastase and porcine pancreatic elastase but not human cathepsin G. It was inactivated by chloramine-T and reactivated when incubated with methionine sulfoxide peptide reductase and dithiothreitol, indicating the presence of a methionine at the active site. The concentration of SLEI in bronchoalveolar lavage fluid (BALF) and lung lymph was 0.28 microM (0.23-0.49); 0.24 microM (0.20-0.31) (median, (range), n = 5), respectively and was undetectable in plasma (< 0.03 microM) suggesting that SLEI is produced in the lung. The median molar ratios of SLEI to alpha1-proteinase inhibitor in BALF and lung lymph were 3.2 to 1 and 0.017 to 1, respectively. These results indicate that SLEI probably makes an important contribution to antielastase defence in epithelial lining liquid.

Sheep mast cell proteinase-1, a serine proteinase with both tryptase- and chymase-like properties, is inhibited by plasma proteinase inhibitors and is mitogenic for bovine pulmonary artery fibroblasts

Sheep mast cell proteinase-1 (sMCP-1), a serine proteinase with dual chymase/tryptase activity, is expressed in gastrointestinal mast cells, and released systemically and on to the mucosal surface during gastrointestinal nematode infection. The potential for native plasma proteinase inhibitors to control sMCP-1 activity was investigated. Sheep alpha1-proteinase inhibitor (alpha1PI) inhibited sMCP-1 slowly, with second-order association rate constant (kass) 1. 1x10(3) M-1.s-1, whereas sheep contrapsin inhibited trypsin (kass 2.2x10(6) M-1.s-1) but not sMCP-1. Western-blot analysis and gel filtration showed that when added to serum or plasma, sMCP-1 was partitioned between alpha1PI and alpha2-macroglobulin. The possibility that significant cleavage of plasma proteins could occur before sMCP-1 was inhibited was investigated using gel filtration and SDS/PAGE after adding sMCP-1 to plasma. Cleavage of ovine fibrinogen occurred in the presence of excess alpha1PI and alpha2-macroglobulin, the alpha-chain being cleaved C-terminally and the beta-chain at the putative Lys-27. In addition, sMCP-1 was found to be mitogenic for bovine pulmonary artery fibroblasts, but was not mitogenic in the presence of soya-bean trypsin inhibitor. In terms of fibrinogen cleavage and fibroblast stimulation, sMCP-1 shows functional similarities to mast cell tryptase.

Purification and partial characterization of an ostrich alpha 1-antichymotrypsin-like serum inhibitor

alpha 1-Antichymotrypsin, a member of the serpins, is the predominant plasma inhibitor of neutrophil cathepsin G. The aim of this study was to purify ostrich alpha 1-antichymotrypsin and to compare its biochemical properties with those of other species. Ostrich alpha 1-antichymotrypsin was purified from serum by ammonium sulphate fractionation, QAE-Sephadex C-50 and phenyl-Toyopearl chromatography. N-terminal sequence, amino acid composition, molecular mass, isoelectric point and reaction with cathepsin G, elastase and chymotrypsin were determined. SDS-PAGE revealed a M, of 55,000 for ostrich alpha 1-antichymotrypsin and pI values of 6.8 and 4.1-4.3 were obtained. The amino acid composition revealed 444 residues and the N-terminal sequence of the first 20 residues revealed a homology of 30% when compared with several other alpha 1-antichymotrypsin sequences. Total inhibition of cathepsin G by ostrich alpha 1-antichymotrypsin was found at a 4:1 molar ratio of inhibitor to enzyme which was similar to that found for commercial alpha 1-antichymotrypsin. Immunological studies highlighted the lack of cross-reactivity between ostrich and human alpha 1-antichymotrypsin. The study indicated that ostrich alpha 1-antichymotrypsin-like molecule exhibited similar properties to human alpha 1-antichymotrypsin although there were notable differences.

The insulin-like growth factor (IGF) binding site of bovine insulin-like growth factor binding protein-2 (bIGFBP-2) probed by iodination

The insulin-like growth factor (IGF) binding site of bovine insulin-like growth factor binding protein 2 (bIGFBP-2) has been probed by chemical iodination. Tyrosyl residues of bIGFBP-2 were reacted by chloramine T-mediated iodination. The modification patterns of free bIGFBP-2 and bIGFBP-2 associated with insulin-like growth factor II (IGF-II) were compared by tryptic mapping using electrospray mass spectrometry and N-terminal sequencing. The presence of bound IGF-II resulted in protection of tyrosine at position 60 from iodination measured by the relative loss of tyrosine specific fluorescence and the incorporation of the radioisotope 125I. In addition, the pattern of iodine incorporation of bIGFBP-2 was not different whether IGF-I or IGF-II was the protective ligand. bIGFBP-2, when iodinated alone sustained a 8-fold loss of binding affinity for IGF-I and a 4-fold loss in binding affinity for IGF-II. In contrast, bIGFBP-2 iodinated while complexed with either IGF-I or IGF-II retained the same binding affinity for IGF-I or IGF-II as non-iodinated bIGFBP-2. We conclude that tyrosine 60 lies either in a region of bIGFBP-2 which directly interacts with both IGF-I and IGF-II or lies in a region of bIGFBP-2 which undergoes a conformational change that is important for IGF binding. Furthermore, iodination of tyrosine residues at positions 71, 98, 213, 226, and 269 has no detectable impact on binding of bIGFBP-2 to the IGFs.

The primary elastase inhibitor (elastasin) and trypsin inhibitor (contrapsin) in the goat are serpins related to human alpha 1-anti-chymotrypsin

Two primary serine proteinase inhibitors in goat plasma have been isolated and characterized. The N-terminal sequence analysis of the purified proteins revealed that they are closely related to each other and are highly homologous to human alpha 1-anti-chymotrypsin rather than alpha 1-proteinase inhibitor. However, despite structural similarities the inhibitory specificity of the goat inhibitors differed from each other and from that of anti-chymotrypsin. In contrast with human anti-chymotrypsin, one of the goat inhibitors was shown to be a strong and specific inhibitor of trypsin (k(ass.) = 1.9 x 10(6) M-1.s-1), whereas the other was an efficient inhibitor of neutrophil elastase (k(ass.) = 1.5 x 10(6) M-1.S-1). Differences in the inhibitory specificity of each protein could readily be attributed to the amino acid sequence within the reactive site region. The trypsin inhibitor with an assumed arginine residue at the P1 position of the reactive-site peptide bond is referred to as 'contrapsin', and indicates that the occurrence of contrapsins is not restricted to rodents. In contrast, the inhibitory specificity, resistance to oxidative and proteolytic inactivation and the presence of a P1 leucine residue in the elastase inhibitor is unique among inhibitory serpins that have been characterized to date. Because this serpin is apparently the major elastase inhibitor in goat plasma, it is likely to be involved in the control of goat neutrophil elastase. Therefore, we suggest the name 'elastasin', and extend it to any other anti-chymotrypsin related serpins possessing neutrophil-elastase- inhibitory activity.

The isolation and partial characterization of alpha 1-proteinase inhibitor from the serum of the ostrich (Struthio camelus)

1. Native and cleaved alpha 1-proteinase inhibitor was purified from ostrich serum using Sepharose-blue dextran chromatography, ammonium sulfate precipitation and ion exchange chromatography on DEAE-Toyopearl 650 M at pH 8.8 and 6.5. Ostrich alpha 1-PI displayed M(r) values of 68,100 using gradient PAGE and 66,200 using Ferguson plots. Isoelectric focusing of ostrich alpha 1-PI in the pH range 3-10 revealed pI values of 4.84 and 4.91, and in the pH range 4-6 the characteristic microheterogeneity observed for mammalian alpha 1-PIs was displayed. The presence of sialic acid, hexoses and hexosamines was detected using chemical methods, but were found in much lower quantities as compared to alpha 1-PIs of other species. Western blot analysis demonstrated a positive reaction between the native and cleaved ostrich alpha 1-PIs and the antibodies to the ostrich alpha 1-PIs raised in rabbits. No cross-reactivity was demonstrated by Western blot analysis between human alpha 1-PI and antibodies to ostrich alpha 1-PI. The inhibitory effect of alpha 1-PI on elastase and chymotrypsin was also investigated.

Complete cDNA sequence of bovine alpha 1-antitrypsin

A cDNA clone coding for the entire bovine alpha 1-antitrypsin molecule has been isolated from a lambda gt11 bovine liver cDNA library using a human alpha 1-antitrypsin cDNA as a probe. The bovine cDNA was sequenced by the dideoxynucleotide chain termination method. Comparison of the translated amino acid sequence of the bovine alpha 1-antitrypsin with those of the human, baboon, sheep, rat and mouse demonstrates the preservation of most of the critical structural determinants. The bovine and the sheep molecules have a sequence homology of 94% and both the molecules contain four cysteine residues; there is only one cysteine in the others.