Characterization of ostrich (Struthio camelus) beta-microseminoprotein (MSP): identification of homologous sequences in EST databases and analysis of their evolution during speciation

Beta-microseminoprotein, alternatively called prostatic secretory protein of 94 amino acids, is a hydrophilic, unglycosylated, small protein rich in conserved half-cystine residues. Originally found in human seminal plasma and prostatic fluids, its presence was later shown in numerous secretions and its homologs were described in many vertebrate species. These studies showed that this protein had rapidly evolved, but they failed to unambiguously identify its biological role. Here, we show that a protein isolated from ostrich pituitary gland is closely related to a similar one isolated from chicken serum and that the two are structurally related to the mammalian beta-microseminoprotein. The complete 90-amino acid sequence of the ostrich molecule was established through a combination of automated Edman degradation and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometric procedures, including postsource decay (PSD) and ladder sequencing analyses. This study documents for the first time that beta-microseminoprotein is present in aves. It is also the first report of a C-terminal amidated form for a member of this protein family and the first in which the disulfide linkages are established. Database searches using the herein-described amino acid sequence allowed identification of related proteins in numerous species such as cow, African clawed frog, zebrafish, and Japanese flounder. These small proteins show a strikingly high rate of amino acid substitutions, especially across phyla boundaries. Noticeably, no beta-microseminoprotein-related gene could be found in the recently completed fruit fly genome, indicating that if such a gene exists in arthropods, it must have extensively diverged from the vertebrate ones.

Purification and partial characterisation of alpha(2)-antiplasmin and plasmin(ogen) from ostrich plasma

This study reports the isolation and partial characterisation of the ostrich serpin, alpha(2)AP, and its target enzyme, ostrich plasmin, in its active and inactive proenzyme, namely plasminogen, forms. Ostrich alpha(2)AP was purified using L-lysine-Sepharose chromatography, ammonium sulfate fractionation, and Super Q-650S and ostrich LBSI-Sepharose chromatographies. It revealed a M(r) of 84 K (thousand) and had one and two N-terminal amino acids in common with 11 of those of human and bovine alpha(2)AP, respectively. It showed the largest inhibitory effect on ostrich plasmin, followed by bovine trypsin and plasmin, respectively, and much less plasmin inhibition than bovine aprotinin, but much more so than human alpha(2)AP, DFP and EACA. Ostrich plasminogen was highly purified after L-lysine-Sepharose chromatography and showed a M(r) of 92 K, a total of 775 amino acids and its N-terminal sequence showed approximately 53% identity with those of human, rabbit, cat, and ox plasminogens. Ostrich plasmin, obtained by the urokinase-activation of ostrich plasminogen, revealed a M(r) of 78 K, a total of 638 amino acids, an N-terminal sequence showing two to four residues identical to five of those of human, cat, dog, rabbit, and ox plasmins, and pH and temperature optima of 8.0 and 40 degrees C, respectively.

Comparative blood coagulation studies in the ostrich

Blood coagulation of the ostrich was compared to that of mammalian (man and sheep), avian (chicken) and reptilian (puff adder) systems. The international normalised ratio (INR), partial thromboplastin time (PTT), thrombin time and fibrin degradation were determined, as well as the various coagulation factors in venous ostrich plasma, using human physiological substrates. Thromboplastin was isolated from fresh brain tissue with the exception of the reptile for which lung tissue was used. The levels of markers of the coagulation [antithrombin III (AT), factor X (FX) and prothrombin], the fibrinolytic (alpha2-antiplasmin) and the kallikrein system were determined using chromogenic substrates. Elevated values for INR, PTT and thrombin time were obtained as compared to known human standards. It was found that factors VII, IX, X, XI and XII were absent from ostrich plasma. A study of the homologous and heterologous thromboplastin activities indicated that ostrich plasma exhibited a lower thromboplastic activity when compared to human standards, but was comparable to avian and reptilian values. Ostrich plasma revealed 42.2% FX, 72.9% AT, 35.3% prothrombin, 115.6% alpha2-antiplasmin and 19.8% plasma kallikrein, relative to human plasma. All the results suggest that the ostrich coagulatory system has not evolved to include all the complex myriad of reactions found in the human system.

The isolation and partial characterization of precursor forms of ostrich carboxypeptidase

Ostrich carboxypeptidases A and B were recently purified and characterized. The aim of this study was to isolate and purify, and partially characterize in terms of molecular weight, pI, amino acid composition and N-terminal sequencing, the precursor forms of carboxypeptidases from the ostrich pancreas. Inhibition studies with soybean trypsin inhibitor and activation studies with three proteases (bovine trypsin, bovine chymotrypsin and porcine elastase) were performed on crude ostrich acetone powder and the carboxypeptidase A and B activities were determined. SDS-PAGE was carried out after every incubation to monitor the rate and degree of conversion of a M(r) 66K component to procarboxypeptidase and carboxypeptidase A and B. The precursor forms were purified by Toyopearl Super Q and Pharmacia Mono Q chromatography. All three proteases converted the M(r) 66K component to procarboxypeptidases and carboxypeptidases over a set time interval, with carboxypeptidase A and B activities being detected in the acetone powder. Chymotrypsin was the preferred protease since it exhibited a more controlled activation of the procarboxypeptidases. The amino acid composition of procarboxypeptidase A revealed 525 residues. The N-terminal sequence of procarboxypeptidase A showed considerable homology when compared with several other mammalian sequences. M(r) and pI values of 52K and 5.23 were obtained for procarboxypeptidase A, respectively. This study indicated that ostrich procarboxypeptidase A is closely related to other mammalian procarboxypeptidase A molecules in terms of physicochemical properties.

Ostrich intestinal glycohydrolases: distribution, purification and partial characterisation

Intestinal glycohydrolases are enzymes involved in assimilating carbohydrate for nutrition. The avian forms of these enzymes, in particular the maltase-glucoamylase complex (MG), are not well characterised. This study encompassed characterisation of these enzymes from ostrich intestines, and the first kinetic analysis of an avian MG. Proteolytically solubilised MG from ileal brush border membrane vesicles was purified by Sephadex G-200 gel filtration and Tris-affinity-chromatography, while jejunal sucrase-isomaltase (SI) and MG were purified by Toyopearl-Q650 and phenyl-Sepharose chromatography. Amino acid sequences and compositions of enzyme subunits, resulting from SDS-PAGE, were determined. Kinetics of hydrolysis of linear oligosaccharides was studied. Ostrich MG and SI showed the highest activity in the jejunum, followed by the ileum and duodenum. No lactase or trehalase activity could be detected. The jejunal MG and SI, resulting from brush-border membrane vesicles, could not be separated during purification. However, a minor form of ileal MG was purified using Sephadex G-200 chromatography. Ileal MG contained three subunits of M(r) 145,000, 125,000 and 115,000. Although the N-terminal amino acid sequences bear no homology to SI, the M(r) 115,000 subunit shows homology to porcine MG in both sequence and amino acid composition. The pH optimum of maltose-, starch- and isomaltose-hydrolysing activity was 6.5 and that of sucrose-hydrolysing activity 5.5. The glycohydrolases were most active at 58 degrees C, but were quickly denatured above 60 degrees C. Sucrose- and starch-hydrolysing activities were more thermostable than maltose- and isomaltose-hydrolysing activities. Kinetic parameters (K(m), kcat and kcat/K(m)) for the hydrolysis of maltooligosaccharides, starch and glycogen are reported for ileal MG. Maltotriose and maltotetraose displayed partial inhibition of ileal MG. The study revealed large similarities between ostrich SI and MG in charge, size, shape and hydrophobicity, based on their inseparability by several methods. Measurement of the specificity constants for maltooligosaccharide hydrolysis by ileal MG revealed less efficient hydrolysis of longer substrates as compared to maltose and maltotriose.

Ovine cardiac Na,K-ATPase: isolation by means of selective solubilization in Lubrol and the effect of 1 alpha,2 alpha-epoxyscillirosidin on this enzyme

The inhibition of cardiac Na,K-ATPase by 1 alpha,2 alpha-epoxyscillirosidin is the principal cause of poisoning of cattle by the tulip, Homeria pallida. The ultimate goals of this study were to study the interaction between 1 alpha,2 alpha-epoxyscillirosidin and ovine Na,K-ATPase by means of inhibition and displacement binding studies. Ovine cardiac Na,K-ATPase was isolated in membrane-bound form by means of deoxycholate treatment, high-speed ultracentrifugation, NaI treatment and selective solubilization in Lubrol. The inhibition of ovine cardiac and commercial porcine cerebral cortex Na,K-ATPase by 1 alpha,2 alpha-epoxyscilirosidin and ouabain was studied using a discontinuous Na,K-ATPase assay. The binding of 1 alpha,2 alpha-epoxyscillirosidin, ouabain and digoxin to the above enzymes was compared using a displacement binding assay with [3H] oubain. The Lubrol-solubilized ovine cardiac Na,K-ATPase showed a specific activity of 0.3 U/mg with no ouabain insensitive activity. I50 values of 2.1 x 10(-8) and 2.7 x 10(-8) were obtained for the inhibition of this enzyme by 1 alpha,2 alpha-epoxyscillirosidin and ouabain, respectively. 1 alpha,2 alpha-Epoxyscillirosidin has a much higher KD value (1.5 x 10(-7) M), however, than ouabain (9.5 x 10(-9) M) and digoxin (1.7 x 10(-8) M) in displacement binding studies with [3H]ouabain. 1 alpha,2 alpha-Epoxyscillirosidin is a potent inhibitor of ovine cardiac Na,K-ATPase and is a slightly stronger inhibitor of the enzyme than ouabain. The anomalous result for the displacement of 1 alpha,2 alpha-epoxyscillirosidin from its receptor is either a result of different affinities that K+ has for the enzyme ouabain and enzyme-1 alpha,2 alpha-epoxyscillirosidin complexes or because of different complex stabilities of these complexes.

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.

Purification and characterization of proteasome from ostrich liver

The proteasome (EC 3.4.99.46) is a high molecular mass (approximately 700 kDa) multisubunit enzyme complex which is the focus of worldwide research in order to identify the structure, mechanism of action and specificity of the complex. The purpose of the present study was to investigate the tryptic, chymotryptic and peptidylglutamyl-peptide hydrolysing (PGPH) activities of ostrich liver proteasome. The proteasome was purified from ostrich liver by employing ammonium sulphate fractionation, followed by three sequential chromatographic steps on Toyopearl Super Q-650 S, Sephadex G-150 and phenyl-Toyopearl columns. Temperature and pH optima were examined and the effect of inhibitors, detergents, fatty acids and cations on the peptidase activities was determined. Ostrich proteasome exhibited a relative M(r) of approximately 665,000 using non-denaturing gradient PAGE and dissociated into the characteristic "ladder" associated with the proteasome subunits during SDS-PAGE. The pH optima for the peptidase activities were found to be slightly alkaline (tryptic activity) and neutral (chymotryptic-like and PGPH activities). Ostrich liver proteasome was found to be activated in terms of the PGPH activity by fatty acids and SDS, whereas the chymotryptic and tryptic-like activities were differentially inhibited. Ostrich proteasome, in its inhibition by monovalent cations, was similar to the proteasomes extracted from other sources. The specificity of the proteasome appears to be very broad, although it lacks aminopeptidase activity. The yield compared favourably with similar extraction procedures which have been reported. On the basis of the physicochemical and kinetic properties which ostrich liver proteasome exhibited, it can be safely concluded that it corresponds well with the proteasomes isolated from many other sources.

Purification and characterization of ostrich pancreatic secretory trypsin inhibitor

Ostrich pancreatic secretory trypsin inhibitor was isolated and purified using acid extraction, salt fractionation. SP-Sephadex C-50 and QAE-Sephadex A-25 chromatography and RP-HPLC. The amino acid sequence of ostrich PSTI showed it is a single peptide chain containing 69 amino acid residues with the highest homology between ostrich and chicken PSTI. The molecular weight, as determined by electronspray mass spectrometry and from amino acid sequence data, is 7650 Da. The isoelectric point of ostrich PSTI was found to be 5.7. Ostrich PSTI specifically inhibited ostrich and commercial bovine trypsin with Ki values of 8.0 x 10(-9) and 2.4 x 10(-7) M, respectively, while no inhibitory effects were observed with other serine proteases.

Ostrich (Struthio camelus) carboxypeptidase B: purification, kinetic properties and characterization of the pancreatic enzyme

Carboxypeptidase B has been isolated from numerous mammalian and invertebrate species. In contrast, very little is known about carboxypeptidases of avian origin. To provide information for a comparative study, we have undertaken an investigation of the kinetic and physical properties of ostrich carboxypeptidase B. Carboxypeptidase B from the pancreas of the ostrich was purified by water extraction of acetone powder and aminobenzylsuccinic acid affinity and hydroxylapatite chromatography. The effects of pH and temperature on CPB activity were examined. K(i)-values for numerous inhibitors (PCI, ABSA, hipp-D-lys, epsilon-aminocaproic acid, D-arg and 3-phenylproprionic acid) and kinetic parameters (K(m), k(cat) and k(cat)/K(m)) for several substrates (hipp-arg, hipp-lys, FAAA, FAAL and hipp-AA) were determined. N-terminal sequencing and amino acid analysis were also performed. Purified ostrich carboxypeptidase B was assessed to be homogeneous by SDS-PAGE with a M(r) value of approx. 35,000. For ostrich carboxypeptidase B the K(m) values for the different substrates were of the same order as those reported for other species, whereas the k(cat) values were 8- to 21-fold lower than the reported values. FAAA and hipp-AA were the preferred substrates. PCI was the most effective inhibitor, with a K(i) in the nM region, and no inhibition was shown with 3-phenylpropionic acid. The N-terminal sequence showed a high degree of homology when aligned with CPB from other species. Amino acid analysis showed significantly lower levels of Asx and Cyh and higher levels of Trp and Leu when compared with other species. Ostrich carboxypeptidase B would appear to show many physical, chemical and kinetic properties similar to those of other known carboxypeptidases.

Ostrich trypsinogen: purification, kinetic properties and characterization of the pancreatic enzyme

Trypsinogen is a serine protease zymogen (EC.3.4.21.4) which has proved to be of key significance in a family of about 20 structurally and functionally related pancreatic digestive enzymes. This study was an endeavour to isolate, purify and characterize a stable form of ostrich trypsinogen, which has thus far not yet been accomplished. Trypsinogen (anionic) was isolated and purified by alkaline extraction of pancreatic acetone powder, followed by Toyopearl DEAE 650M, hydroxylapatite and LBTI-Sepharose affinity chromatography. The enzyme was chemically physically and kinetically characterized, using amidase and esterase activity and spectrofluorometric determinations. Effects of CaCl2 and pH, among others, were examined. Purification of homogeneous anionic ostrich trypsinogen was achieved. Immunochemical analysis and spectrofluorometric reaction with sulphonyl-Ala-Ala-Pro-Arg-7-amino-4-methylcoumarin indicated trypsin-free ostrich trypsinogen, with an average Mr of 23,016 and a pI of 4.93. N-terminal sequence data revealed an unique activation peptide sequence, VPGDADDDK. Certain concentrations of Ca2+ enhanced trypsinogen activation, whilst others appeared to have the opposite effect. The kcat/Km values obtained at different pHs, using N alpha-benzoyl-DL-arginine-p-nitroanilide, p-toluenesulphonyl-arginine-methylester and p-toluenesulphonyl-lysine-methylester, followed the pH profile activity trend closely, with maximum catalytic activity at about pH 8 for both ostrich and bovine activated trypsinogen. Ostrich trypsin has significantly higher amidase activity than bovine trypsin, while esterase activities of the two enzymes have an inverse ratio. Kinetic pKa values were 7.2 and 7.4 for ostrich and bovine activated trypsinogens, respectively. The existence of ostrich trypsinogen in a now homogeneous stable form, free of autocatalytic inducing impurities, together with its characterization scenario will hopefully make a significant contribution to the field of comparative biochemistry. This study also confirms that ostrich trypsinogen is closely related to its serine protease counterparts.

Ostrich pepsinogens I and II: purification, activation and chemical and immunochemical characterization of the enzymes from the proventriculus

Pepsins are a series of gastric proteases secreted as inactive precursors (pepsinogens) which are active at acidic pH. The aim of this study was to purify ostrich pepsin(ogen)s and to compare their biochemical and immunological characteristics with those of pepsin(ogen)s of mammalian and avian origin. Ostrich pepsinogens were purified by ammonium sulphate fractionation, Toyopearl Super Q-650S chromatography and rechromatography, and hydroxylapatite chromatography of a pH 8.0 mucosal extract. Pepsins were obtained through acidification, and purified by chromatography on SP-Sephadex C-50. Amino acid compositions, N-terminal sequences, Ouchterlony double-diffusion as well as Western blot analysis were performed. Two pepsinogens were isolated and purified from the proventriculus of the ostrich, pepsinogens I and II. Both pepsinogens and pepsins were purified to homogeneity as shown by PAGE and SDS-PAGE, with SDS-PAGE revealing M(r) values of 40,400 and 41,900 for pepsinogens I and II, respectively. SDS-PAGE revealed M(r) values of 36,000 and 36,300 for ostrich pepsins I and II, respectively. Ostrich pepsinogens I and II were found to have identical N-terminal sequences, with Asp as N-terminal amino acid. Amino acid compositions were obtained for both pepsinogens, with ostrich pepsinogen I being slightly smaller in size with a total of 356 residues compared to 371 for ostrich pepsinogen II. Pepsinogen II showed a pI of 4.29. Ostrich pepsinogens I and II were found to be immunologically separate entities, and no cross-reactivity was observed between anti-(ostrich pepsinogen I/II) sera and porcine pepsin/pepsinogen. The study indicates that only two pepsinogens are present in the ostrich. They differ in terms of electrophoretic mobility, molecular mass and immunological reactivity, but have been found to have identical N-terminal sequences. It is concluded that both pepsinogens belong to the pepsinogen A class of aspartyl proteases (EC 3.4.23.1).

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.

Ostrich (Struthio camelus) carboxypeptidase A: purification, kinetic properties and characterization of the pancreatic enzyme

1. Carboxypeptidase A beta and carboxypeptidase A tau-type from the pancreas of the ostrich were purified by water extraction of acetone powder, aminobenzylsuccinic acid affinity and hydroxylapatite chromatography. 2. The final preparations were homogeneous when subjected to SDS-PAGE and PAGE. The M(r) values obtained from SDS-PAGE for CPA beta and CPA tau-type were 34,600 and 34,400, respectively. 3. The effects of inhibitors (1,10 phenanthroline and indole-3-acetic acid), pH and temperature on CPA activity were examined. Ki-values for CPI, PPA, D-phe, D-trp and aminobenzylsuccinic acid were determined. 4. Km, kcat and kcat/Km values were determined for hipp-phe, cbz-gly-phe, cbz-(gly)2-phe, cbz-gly-leu, cbz-(gly)2-leu and cbz-(gly)2-val. 5. N-terminal sequencing and amino acid analysis were performed for CPA beta and CPA tau-type.

The isolation and partial characterization of alpha 2-macroglobulin from the serum of the ostrich (Struthio camelus

1. alpha 2-Macroglobulin (alpha 2M) activity is present in the serum of the ostrich, Struthio camelus. The chromogenic synthetic peptide substrates BAPNA and ATNA were hydrolysed by trypsin and chymotrypsin, respectively, in the presence of ostrich serum and the alpha 2 M in ostrich serum protected trypsin from being inhibited by soybean trypsin inhibitor. Ostrich alpha 2M proved to be a potent inhibitor of bovine pancreatic trypsin and chymotrypsin. 2. alpha 2M was purified to apparent homogeneity by PEG precipitation, DEAE-Toyopearl 650M, Bio-Gel A-5m and Zn(2+)-affinity chromatography. 3. Ostrich alpha 2M migrated as a single band (M(r) 779,000 during non-denaturing gradient gel electrophoresis and showed increased mobility after reaction with trypsin. Denaturation dissociated ostrich alpha 2M into half-molecules. Denaturation with reduction further dissociated the protein into quarter-subunits. 4. Isoelectric focusing revealed a pI of 5.3. 5. The amino acid composition of ostrich alpha 2M is typical of an alpha 2M, comparing favourably with those of other animal species. The carbohydrate composition of the purified protein, in percentage dry weight of the molecule, was galactose: mannose (1:1), 4.55; N-acetylglucosamine 2.35; N-acetylneuraminic acid, 0.58; and fucose, 0.77. 6. alpha 2M was assessed immunologically by Ouchterlony double-diffusion and Western blot analysis with polyvalent antisera directed against ostrich alpha 2M. 7. Ostrich alpha 2M seems to show many physical, chemical and kinetic properties similar to those of other known alpha 2M(s), but is expected to differ from other alpha Ms when considering the primary structure of the bait region, the area differing among alpha Ms from different species and determining its specificity.

The production of the ostrich NH2-terminal POMC fragment requires cleavage at a unique signal peptidase site

The NH2-terminal fragment of ostrich proopiomelanocortin was isolated and purified following acid/acetone extraction. The amino acid sequence was deduced by automatic Edman degradation of the native as well as CNBr-, tryptic-, and S. aureus protease-derived peptides. Primary structure analysis reveals its close resemblance to other known sequences, especially to amphibian POMC. The usual Trp/Gln-Cys NH2-terminal sequence found in all other homologous sequences, is replaced here by an His-Gly-Pro-Cys sequence. In addition, the gamma-MSH sequence, contrary to salmon POMC, is present and contains three substitutions, namely a Ser, an Asn, and a Lys residue substituting the normally occurring mammalian Gly, Asp, and Arg residue, respectively. Finally, the molecular weight of this fragment as deduced from ion-spray mass spectrometry and sedimentation equilibrium centrifugation is in close agreement with the proposed structure.

The isolation and partial characterization of trypsinogen, pancreatic secretory trypsin inhibitor and multiple forms of chymotrypsinogen and trypsin from the pancreas of the ostrich (Struthio camelus)

1. PSTI, two chymotrypsinogens and two trypsins were purified to homogeneity by acid extraction, salt fractionation, SP-Sephadex C-50 chromatography and RP-HPLC. 2. A third chymotrypsinogen, a trypsinogen and another trypsin were purified using an alkaline extraction procedure, followed by Trasylol- and Benzamidine-Sepharose affinity chromatography and hydroxylapatite chromatography. 3. The enzymes differed in amino acid composition as well as in specific activities towards synthetic amidase and esterase substrates. 4. N-terminal amino acid sequences were determined for one chymotrypsinogen and one trypsin.

The effect of prolonged exercise and in vivo treatment with ACTH and norepinephrine on plasma cortisol and on the levels of energy metabolites in liver, muscle and blood of the guinea pig (Cavia porcellus)

1. Exercise and in vivo treatment with adrenocorticotrophic hormone (ACTH) showed a marked tendency to increase in vivo plasma cortisol levels in the guinea pig (Cavia porcellus). 2. However, in vivo norepinephrine (NE) treatment did not have any notable effect on plasma cortisol levels. 3. Metabolite levels (glycogen, glycerol and lactate) in liver and plantaris and soleus muscle, and the levels of glucose, glycerol and lactate in blood, were determined in response to the same treatments. 4. A number of statistically significant changes, as well as certain trends, in metabolite levels were observed in response to the treatments and are discussed.

The effect of exercise and in vivo treatment with ACTH and norepinephrine on the lipolytic responsiveness of guinea pig (Cavia porcellus) adipose tissue

1. In adipose slices of the guinea pig (Cavia porcellus), adrenocorticotrophic hormone (ACTH) produced a significantly higher lipolytic response (increased Vmax and decreased Km) as compared to norepinephrine (NE), thus indicating a marked difference with human adipose tissue. 2. Exercise-training caused a significant increase in the affinity of the lipolytic response in adipose tissue towards both ACTH and NE, but had no significant effect on Vmax. 3. Prolonged in vivo treatment with both ACTH and NE significantly decreased the responsiveness (affinity and capacity) of adipose slices towards ACTH. Responsiveness towards NE was much less affected.

Binding and spectroscopic properties of ostrich neurophysins. Probing the role of residue 35 at the monomer-monomer interface

Binding and spectroscopic properties of ostrich neurophysins were examined with emphasis on the behavior of Tyr-35, a residue that provides a potential probe of the monomer-monomer interface and of allosteric interrelationships between this region and the binding site. Mesotocin-associated ostrich neurophysin was found to bind oxytocin and related peptides with affinities comparable to the mammalian proteins, but induced a significantly different optical activity in bound peptides than the mammalian proteins. Gel-filtration studies indicated higher dimerization constants for the ostrich neurophysins than for the bovine neurophysins. Consistent with this, Tyr-35 was found to be largely buried, as monitored by tyrosine titration and lack of reactivity towards tetranitromethane under non-denaturing conditions. Reaction of Tyr-35 of the mesotocin-associated protein with tetranitromethane under denaturing conditions, followed by refolding, allowed isolation of an active product with an altered interface region as partially evidenced by its titration properties and consistent with its markedly altered CD spectrum. Comparison of the CD spectra of the modified and native proteins and analysis of pH effects indicated the contribution of Tyr-35 to an unusual 237 nm band in the mesotocin-associated protein. Small shifts in the 350 nm CD band of nitrated Tyr-35 on binding peptide and apparent effects of nitration on the induced optical activity in bound peptide provided evidence of at least weak structural communication between Tyr-35 and the binding site. However, no significant effect of nitration on binding affinity was observed, suggesting that, in the mesotocin-associated protein, the region around residue 35 is not a stringent modulator of the thermodynamic behavior of the binding site.

The ostrich pituitary contains a major peptide homologous to mammalian chromogranin A(1-76)

A major peptide related to the NH2-terminal fragment (position 1 to 76) of mammalian chromogranin A was isolated from ostrich adenohypophyses following acid-acetone extraction. The complete amino acid sequence of the homogenous peptide was deduced following automatic Edman degradation of the native peptide as well as of CNBr-, tryptic- and Lysobacter-derived peptides. The 76 amino acid sequence is strikingly homologous to bovine (80.3% sequence identity), porcine (79.0%), human (79.0%) and rat (72.4%) corresponding sequences, but much less so to human chromogranin B (22.4%). As this peptide is followed in bovine, porcine and human structure by a pair of basic residues (Lys-Lys), it could conceivably be produced during maturation in secretory granules. Finally, its structure appears to contain two potential amphipathic helices joined by the single disulfide bridge present in all chromogranin A and B molecules.

Ostrich MSEL-neurophysin belongs to the class of two-domain "big" neurophysin as indicated by complete amino acid sequence of the neurophysin/copeptin

Mammalian neurohypophyseal hormones, oxytocin and vasopressin, are known to be synthesized as part of two larger precursors containing, respectively, a VLDV-neurophysin and a MSEL-neurophysin together with its associated glycopeptide. Starting from ostrich neurohypophyses, a "big" neurophysin was isolated and chemically characterized. Following sequence determination of the CNBr-derived fragments and of peptides obtained from trypsin and V8-protease digestion of the oxidized protein, this "big" neurophysin was found to contain an MSEL-neurophysin moiety (94 residues) still covalently associated with the COOH-terminal glycopeptide (38 residues, copeptin). This study demonstrates that the ostrich MSEL-neurophysin sequence closely resembles all known MSEL-neurophysin sequences and that, furthermore, it does not contain the single amino acid insertion shown previously in the ostrich VLDV-neurophysin. It is also shown that the stretch of amino acids, linking the MSEL-neurophysin and the copeptin, is clearly different from its mammalian homologues and lacks the Arg residue normally recognized by the cleaving enzyme. This study also demonstrates that the ostrich copeptin is more closely related to the amphibian copeptin sequence than to its mammalian homologue, leading to the hypothesis that two families of copeptin molecules might exist. Thus, the ostrich MSEL-neurophysin-copeptin molecule is the first "big" neurophysin reported in birds and, together with the guinea pig and amphibian homologues, represents the third example of partial or no neurophysin-copeptin cleavage.

The isolation and partial characterization of chymotrypsinogen from the pancreas of the ostrich (Struthio camelus)

1. Cationic chymotrypsinogen from the pancreas of the ostrich was purified to homogeneity by sulfuric acid extraction of pancrei, (NH4)2SO4 fractionation and SP-Sephadex C-50 and Sephadex G-100 chromatography. 2. The final preparation was homogeneous when subjected to SDS-PAGE, isoelectric focusing and sedimentation equilibrium centrifugation. The Mmin value obtained from amino acid analysis was 25,572 Da. A mean sedimentation coefficient of 2.575 S was obtained by sedimentation velocity centrifugation. 3. N-terminal analysis by dansylation showed an Ala residue which is the N-terminal of a neochymotrypsinogen. 4. The effects of pH, temperature and inhibitors (LBTI, PMSF, TPCK and DFP) on the chymotryptic activity were examined. A Km-value for ATEE as substrate was found to be 0.57 mM.

Complete amino acid sequence of a VLDV-type neurophysin from ostrich differs markedly from known mammalian neurophysins

The neurohypophyseal hormones vasopressin and oxytocin are known to be synthesized in eutherian mammals as part of larger precursors containing either MSEL- or VLDV-neurophysins. A neurophysin has been isolated from ostrich neurohypophyses and shown by partial amino acid sequence determination to be related to mammalian VLDV-neurophysin. The present report describes the complete amino acid sequence of this ostrich neurophysin containing 93 residues. This amino acid sequence, the first reported in birds, differs in a remarkable manner from its mammalian homolog. Indeed, it contains a large number of substitutions, including one insertion, distributed throughout the polypeptide chain when compared to known VLDV-neurophysins. Whereas many of these substitutions are localized inside the so-called constant region of the neurophysin, the highest variation can be found in the COOH-terminal region.

In vitro lipolytic activity of beta-endorphin and its partial sequences

beta-Endorphin stimulates glycerol release from adipose tissue in vitro in the rabbit. Thirty different amino acid sequences of this peptide were tested for lipolytic activity. Four turned out to be active: porcine and human beta-endorphin-(1-31), human beta-endorphin-(6-31), and human beta-endorphin-(1-5)-(16-31). Structure-activity investigations showed that for the lipolytic action of beta-endorphin the C-terminal part [longer than beta-endorphin-(27-31)] is relatively important. Of special importance seems to be the C-terminal amino acid residue, because none of the sequences lacking the last two amino acid residues was lipolytically active. Furthermore, a different lipolytic response to beta-endorphin was obtained in starved, ad libitum-fed, and starved-refed animals, showing that the regulation of the lipolytic potency is not only mediated by peptide concentrations in the medium.

The isolation and partial characterization of trypsin from the pancreas of the ostrich Struthio camelus

Cationic trypsin was isolated and purified from the pancreas of the ostrich (Struthio camelus) by affinity chromatography on a Trasylol-Sepharose column. External activation of trypsinogen was required before trypsin could be isolated. The final preparation was homogeneous by SDS-PAGE and by sedimentation equilibrium centrifugation studies, resulting in Mr values of 24,547 and 22,091, respectively. The Mmin value obtained from amino acid analysis was 22,450. A mean sedimentation coefficient of 2S was obtained by sedimentation velocity centrifugation. Results obtained from N-terminal and amino acid analyses were similar to those from trypsins of other species. The effects of pH, temperature and inhibitors (LBTI, KBPTI and PMSF) on the tryptic activity were examined. The effect of calcium ions and enzyme concentration on the rate of self-digestion of ostrich trypsin was also investigated.

Mesotocin and vasotocin, two neurohypophysial hormones in the ostrich, Struthio camelus

Two neurohypophysial hormones have been isolated from an avian species, the ostrich, Struthio camelus. Both have been characterized by amino acid analysis and sequence determination. The data obtained suggest that the oxytocin-like hormone is [Ile8-oxytocin] (mesotocin) and the vasopressin-like hormone is [Ile3-vasopressin] (vasotocin). Bioactivity measurements based on urinary conductivity showed vasotocin to be about five times as active as mesotocin.

Isolation and characterization of a neurophysin from ostrich neurohypophyses

A neurophysin has been isolated from ostrich neurohypophyses using acid acetone extraction, salt fractionation and Sephadex G-75 chromatography. The crude neurophysin eluting from the Sephadex G-75 column was subjected to a) reverse-phase HPLC followed by Sephadex G-75 chromatography, b) DEAE-Sephadex A-50 chromatography or c) isoelectric focusing. The different homogeneous ostrich neurophysin fractions so obtained were compared i.t.o. amino acid composition, spectral properties, N-terminal amino acid residues and PAGE. They all revealed a single N-terminal Ala residue and displayed spectral properties (A280/A260 less than 1) which are typical of mammalian neurophysin-like polypeptides. Ultracentrifugation studies on purified ostrich neurophysin over a range of concentrations revealed a reversible concentration dependent association behaviour characterized by the presence of dimeric complexes at higher concentrations. Partial sequencing from the N-terminus revealed the molecule to be VLDV-like. The purified molecule was also submitted to CNBr fragmentation.

The isolation and characterization of serum albumin from the ostrich (Struthio camelus)

Ostrich serum albumin (OsSA) was purified by a combination of heat fractionation and polyethylene glycol precipitation. Equilibrium centrifugation revealed a relative molecular mass of 71,666 for the purified monomer, whereas the presence of a dimeric form was confirmed by means of PAGE and SDS-PAGE analysis. Compared to other species, relatively high levels of proline, glycine, isoleucine and histidine together with lowered amounts of half cystine, phenylalanine and arginine were observed in OsSA. A single N-terminal aspartic acid was identified. Isolated chicken adipocytes revealed a significantly lower in vitro lipolytic responsiveness towards added glucagon when OsSA replaced bovine serum albumin (BSA) in the medium (Km = 6.359 and 1.135 nM, Vm = 36.70 and 46.72 nmol/hr/micrograms adipocyte DNA for OsSA and BSA respectively).

The isolation and characterization of pepsinogens from the proventriculus of the ostrich Struthio camelus

Three pepsinogens were isolated and purified from the proventriculus of the ostrich Struthio camelus, by a combination of chromatography steps on DEAE-cellulose, Sephadex G-100 and Hydroxylapatite. The purified pepsinogens manifested peptic activity towards haemoglobin as substrate after activation, but resembled chicken pepsinogens in that they appeared to lose their potential peptic activities during storage. All three pepsinogens contained glycine as N-terminal amino acid, but differed in their overall amino acid compositions. The pH and temperature optima of the activated pepsinogens were determined, as well as their molecular weights.

A comparative study on the steroidogenic response due to training and ACTH treatment in the adrenal cortex of the male rat

The aim of this study was to ascertain the effects of training and ACTH administration on the steroidogenic in vitro response in the adrenal cortex of the rat when the tissue was incubated with ACTH. ACTH in vivo treatment resulted in a highly significant increase in the steroidogenic response (P less than 0.001) whereas training as such caused only a slight but insignificant increase in the steroidogenic responsiveness (P greater than 0.05). Training furthermore strongly suppressed the ACTH in vivo induced response (P less than 0.001). ACTH as such revealed the smallest effect on adrenal mass but the biggest effect on the steroidogenic response. It would seem that long term exercise resulted in an overall increase in the mass and size of the adrenal glands by either increasing the size of existing cells or by increasing the number of cells or both. The latter exercise-induced proliferation of adrenal tissue may involve an adaptive mechanism whereby larger total quantities of adrenal tissue of lowered steroidogenic efficiencies (on a mass basis) are produced in order to meet the stress resulting from the training program.

Isolation and characterisation of a novel peptide from ostrich adenohypophyses

A novel peptide has been isolated from ostrich pituitary glands using acid acetone extraction, salt fractionation, ion exchange and gel permeation chromatography and preparative paper electrophoresis. The homogeneous fraction contained a large proportion of hydrophobic amino acids apparently concentrated in a portion of the polypeptide. An amino-terminal isoleucine and carboxyl-terminal glutamine were found. The molecular weight was determined as 15 024 (ultracentrifugation) and 16 185 (amino acid analysis). A single intra-molecular disulfide bond was determined. The isoelectric point was 6.5. A possible role as part of a hormone precursor is suggested.

Isolation and characterization of beta-lipotropin from the pituitary gland of the ostrich, Struthio camelus

Avian beta-lipotropin (beta-LPH) was purified from adenohypophyseal glands of the ostrich Struthio camelus by a procedure involving acid/acetone extraction, NaCl fractionation, CM-cellulose chromatography, Sephadex G-75 chromatography and paper electrophoresis (pH 6.7). The 90-amino acid peptide behaved as a single substance during polyacrylamide-gel electrophoresis, isoelectric focusing (pI of 6.0) and N-terminal analysis, the N-terminal amino acid being alanine. Ostrich beta-LPH exhibited lipolytic activity corresponding to an average minimal effective dose of 0.088 micrograms in rabbit adipose tissue.

beta-Lipotropin: primary structure of the hormone from the ostrich pituitary gland

The amino acid sequence of beta-lipotropin from the ostrich pituitary has been determined. It consists of 79 amino acids. The amino acid sequence has been determined as follows: H-(1)AlA-Leu-Pro-Pro-Ala-Ala-Met-Leu-Pro-(10)Ala-Ala-Ala-Glu-Glu-Glu-Glu-Gly-Gl u-Glu-(20)Glu-Glu-Glu-Gly-Glu-Ala-Glu-Lys-Glu-Asp-(30)Gly-Gly-Ser-Tyr-Arg-Met-A rg-His-Phe-Arg-(40)Trp-Gln-Ala-Pro-Leu-Lys-Asp-Lys-Arg-Tyr-(50)Gly-Gly-Phe-Met- Ser-Ser-Glu-Arg-Gly-Arg-(60)Ala-Pro-Leu-Val-Thr-Leu-Phe-Lys-Asn-Ala-(70)Ile-Val -Lys-Ser-Ala-Tyr-Lys-Lys-Gly-(79)Gln-OH. When compared with the primary structures of other known beta-lipotropins, the sequence at the NH2-terminal, beta-melanotropin and beta-endorphin portions of the molecule exhibit considerable variability.

Isolation, characterization and opiate activity of beta-endorphin from the pituitary gland of the ostrich, Struthio camelus

1. Avian beta-endorphin was purified from adenohypophyseal glands of the ostrich Struthio camelus by a procedure involving acid/acetone extraction, NaCl fractionation, CM-cellulose chromatography, Sephadex G-50 chromatography and paper electrophoresis (pH 6.7). 2. The 31-amino acid peptide behaved as a single substance during polyacrylamide-gel electrophoresis and isoelectric focusing, the isoelectric point being 8.84. 3. Ostrich beta-endorphin exhibited significant opiate activity in the guinea-pig ileum preparation.

The isolation and characterization of corticotropin from the pituitary gland of the ostrich Struthio camelus

1. Avian corticotropin (ACTH) was purified from both fresh and aged pituitary glands of the ostrich Struthio camelus. 2. The isolation of corticotropin in pure form involved acid/acetone extraction, NaCl fractionation, CM-cellulose chromatography and Sephadex G-50 chromatography. 3. The hormone preparations from fresh and aged glands behaved as single substances on polyacrylamide-gel electrophoresis, and both preparations were found to consist of 39 amino acid residues, in identical molar proportions for the different amino acids. 4. The isoelectric points of the two hormone preparations were estimated to be in the range pH 8.3-8.7, indicating possible differences in amide content, and the N-terminal amino acid of both preparations appeared to be serine. 5. The hormone preparations from fresh and aged glands exhibited similar biological potencies (73 and 77 i.u./mg respectively), as measured by steroidogenesis in vitro. 6. Apart from possible differences in amide content, the corticotropin preparations obtained from fresh and aged glands appear to be indistinguishable.