Highly simplified analytical or preparative slab gel electrophoresis

Ontogenic development of liver progesterone metabolism in female sheep. Contribution of cytochrome P4502B and P4503A subfamilies

Age-related changes in progesterone hepatic metabolism were measured in Lacaune ewes in the foetal, neonatal (1 and 4 weeks), growing (7 months), pregnant (11 months) and adult (6 years) stages. 6 beta-Hydroxylation and 20 alpha-reduction were found to be the most efficient metabolic process in ovine microsomes. These activities were detected in 3-month-old foetuses and they increased rapidly during the first month of life, in a similar manner to the developmental expression of the cytochrome P4503A subfamily. 16 alpha- and 21-hydroxylation of progesterone were characterized by low, constant turn over in sheep liver microsomes during development. The hepatic ovine P4502B isozyme was purified to electrophoretic homogeneity by means of successive DEAE cellulose, hydroxylapatite and CM cellulose chromatographic separations. This hemoprotein had an apparent molecular weight of 51 kDa and was characterized by spectral data, NH2-terminal amino-acid sequence, immunological and catalytic properties. The relative contribution of this form and of the previously purified ovine P4503A subfamily was investigated in liver progesterone metabolism by immunoinhibition studies using polyclonal antibodies raised in rabbits and from the existence of induction and of significant correlations between microsomal activity and specific P450 content. In sheep liver microsomes, it would appear that cytochrome P4502B is involved in progesterone 21-hydroxylation whereas P4503A participates in the 6 beta- and 16 alpha-hydroxylation and possibly in the reductive conversion of progesterone in its 20 alpha-hydroxy derivative.

Purification of a sheep liver cytochrome P-450 from the P450IIIA gene subfamily. Its contribution to the N-dealkylation of veterinary drugs

Oral administration of troleandomycin at a dose of 100 mg/kg/day for 6 days to three adult male Lacaune sheep produced a 1.6-fold increase in specific content of liver microsomal cytochrome P-450. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis, microsomal preparations from treated animals exhibited a strong band in the zone of electrophoretic mobility of cytochromes P-450. This band corresponded to a cytochrome P-450 which cross-reacted with rabbit P450IIIA6 antibodies, as demonstrated by immunoblotting. The ovine isozyme was purified to electrophoretic homogeneity by means of successive DEAE cellulose, CM cellulose and hydroxylapatite chromatographic separations. This hemoprotein had an apparent molecular weight of 52 kD as determined by calibrated sodium dodecyl sulfate-polyacrylamide gel electrophoresis and was characterized in terms of spectral data, NH2-terminal amino acid sequence, immunologic and catalytic properties. This study revealed some interspecies differences with the orthologous rabbit isozyme. The contribution of this form to the N-demethylation of erythromycin and of three veterinary drugs: chlorpromazine, chlorpheniramine and bromhexine was demonstrated from inhibition by TAO, from immunoinhibition studies, using polyclonal antibodies raised in rabbit and from the existence of significant correlations between its microsomal level and these N-demethylase activities. In contrast, the results suggest that ovine P450IIIA could not be predominantly involved in the N-dealkylation of benzphetamine, ephedrine, ivermectine or spiramycin.

Differences in adhesion of Pseudomonas aeruginosa to mucin glycopeptides from sputa of patients with cystic fibrosis and chronic bronchitis

Pseudomonas aeruginosa is the most prominent colonizer of the respiratory tract of patients with cystic fibrosis, but it is not known why this occurs. P. aeruginosa adheres to mucins from normal individuals, but mucins from cystic fibrosis patients have not been studied. To compare adhesion to mucins from cystic fibrosis with other mucins, we prepared highly glycosylated mucin glycopeptides from cystic fibrosis and chronic bronchitis patients by ion-exchange and gel-filtration chromatography and measured the adhesion of P. aeruginosa 1244 to these glycopeptides. We found (i) that the most mucinlike glycopeptides from P. aeruginosa-infected cystic fibrosis sputa showed less bacterial adhesion than did the corresponding bronchitis samples, (ii) that the most adhesive activity in cystic fibrosis samples came from a fraction that contains O and N glycopeptides and may be in part a degradation product of P. aeruginosa infection, and (iii) that highly glycosylated glycopeptides of the most acidic species (sialylated and sulfated) showed no adhesion at all. A single cystic fibrosis sample not infected by P. aeruginosa showed better binding in the adhesion-positive fractions than did the infected sputa. These studies suggest that cystic fibrosis mucins may be altered after infection is established, resulting in less binding to some fragments. However, since the clinical picture shows heavy mucus colonization, other receptors, such as cellular glycolipids which have been shed into mucus, may be contributing to this colonization.

Evidence for the in vivo degradation of human respiratory mucins during Pseudomonas aeruginosa infection

The comparison of distribution of glycopeptides of sputa from patients suffering from various chronic hypersecretions has already shown an increased acidity with a decreased proportion of neutral glycopeptides in the respiratory secretions of patients suffering from cystic fibrosis, as compared to those of patients with chronic bronchitis. In order to find out whether this decrease is specific to cystic fibrosis mucins or whether it is due to a degradation of mucus by Pseudomonas aeruginosa, which infects most of the sputa from patients with this disease, mucus glycopeptides from patients with different chronic bronchial disorders, infected by Pseudomonas or not, were prepared and fractionated by ion-exchange chromatography. The neutral fraction, which has never been studied in detail, was gel-filtered, and provided two fractions, one containing true mucin glycopeptides and the other containing a mixture of peptides and glycopeptides with a lower molecular mass. In the Pseudomonas-infected samples, the true mucin glycopeptide fraction was greatly diminished as compared to this same fraction in non-Pseudomonas-infected samples; this was not specific to cystic fibrosis secretions. In contrast, the glycopeptide fraction with a lower molecular mass was greatly increased in all the Pseudomonas-infected samples. Polyacrylamide gel electrophoresis of this second fraction showed unique glycopeptide bands between 40-50 kDa in the Pseudomonas-infected samples, regardless of the origin of the samples. These bands were revealed by an antibody directed against whole cystic fibrosis mucin. Infected chronic bronchitis sputa and cystic fibrosis samples without P. aeruginosa did not show these bands. These studies therefore suggest that there are P. aeruginosa-associated changes in mucins which may result from degradation of mucins.

Characterization of the chromosomal protein MC1 from the thermophilic archaebacterium Methanosarcina sp. CHTI 55 and its effect on the thermal stability of DNA

In the deoxyribonucleoprotein complex of Methanosarcina sp. CHTI 55, DNA is associated with two proteins, named MC1 (methanogen chromosomal protein 1) (Mr 10,760) and MC2 (Mr 17,000). Protein MC1, the most abundant of these proteins, is closely related to the Methanosarcina barkeri MS protein MC1. The effect of Methanosarcina sp. CHTI 55 protein MC1 on the thermal stability of DNA has been studied in native deoxyribonucleoprotein complex, as well as in reconstituted complexes, and it has been compared to the effect of E. coli DNA-binding protein II. Both proteins are able to protect DNA against thermal denaturation, but the differences observed in the melting profiles suggest that they interact by different mechanisms. Moreover, our studies indicate that one molecule of protein MC1 protects eight base pairs of DNA.

Purification and partial characterization of two lectins from the cactus Machaerocereus eruca

Two lectins (MEAI and MEAII) were isolated from the cactus Machaerocereus eruca by affinity chromatography on mucin-Sepharose and partially characterized with respect to their biochemical and carbohydrate binding properties. Both are oligomeric glycoproteins consisting of 35 kDa monomers. Amino acid analysis indicates that both lectins have similar composition with high amounts of glycine, glutamic acid and serine. MEAI and MEAII contain approximately 36 and 24% (w/w) of carbohydrates, respectively. They agglutinate erythrocytes from several animal species. Binding specificity was directed to galactose-containing oligosaccharides and glycopeptides. The M. eruca lectins are the first lectins to be isolated from a species belonging to the plant family of Cactaceae.

Action of trifluoromethanesulfonic acid on highly glycosylated regions of human bronchial mucins

Highly glycosylated glycopeptides were prepared from human bronchial mucus. They were heterogeneous and contained an average of 45 residues of glycosylated hydroxyamino acid per 100 amino acid residues. The kinetics of deglycosylation of these glycopeptides by trifluoromethanesulfonic acid-anisole mixtures at 25 degrees was monitored by chemical analysis and by polyacrylamide gel electrophoresis. The peripheral sugars were almost completely cleaved in 45 min with 3:2 and 2:1 CF3SO3H-anisole. A maximum of 75% of the O-linked N-acetylgalactosamine residues were released and mixtures of glycopeptides and peptides were obtained. Increasing the reaction time caused peptide bond cleavage. Rather mild conditions (1.2:1 CF3SO3H-anisole at 25 degrees for 90 min) gave limited deglycosylation of highly glycosylated bronchial glycopeptides, allowing the uncovering of GalNAc-peptide linkages and peptide regions able to induce the formation of specific antibodies in the rabbit.

Evidence for interactions between the 30 kDa N- and 50 kDa C-terminal tryptic fragments of human lactotransferrin

Gel filtration of a mild tryptic digest of diferric human lactotransferrin carried out in presence of 10% (v/v) acetic acid led to the isolation of two fragments, an N-terminal tryptic fragment having an Mr of 30,000 and a C-terminal tryptic fragment having an Mr of 50,000 [Legrand, Mazurier, Montreuil & Spik (1984) Biochim. Biophys. Acta 787, 90-96]. Both fragments possess a degree of organization lower than that of the native protein, as shown by the decrease of about 30% of the alpha-helical content observed by c.d. The two fragments are able to re-associate in neutral solutions, as shown by the isolation, by gel chromatography, of a re-associated 80 kDa N,C-tryptic complex having the chromatographic behaviour of the native lactotransferrin. Computer-based comparison of the measured c.d. spectrum of the mixture of N-tryptic and C-tryptic fragments (molar ratio 1:1) with the spectrum calculated by assuming one molecule of each fragment, shows that the alpha-helix content of lactotransferrin is restored. These results strongly suggest the existence of non-covalent and reversible interactions between the two lobes of lactotransferrin. In addition it was demonstrated that short peptide segments (residues 19-24, 45-58 and 264-276) are involved in the secondary-structure modifications referred to above.

Visualization of lactotransferrin brush-border receptors by ligand-blotting

The uptake of iron (III) mediated by lactotransferrin to human biopsies from upper intestine has suggested the presence of specific receptors for human lactotransferrin at the brush border (Cox, T., Mazurier, J., Spik, G., Montreuil, J. and Peters, T.J. (1979) Biochim. Biophys. Acta 588, 120-128). In the present data, using 125I-radiolabeled transferrins, we have demonstrated that a preparation of microvillous membrane vesicles, from rabbit jejunal brush-border specifically binds human lactotransferrin. This binding is specific, saturable and calcium dependent. Scatchard plots analysis of lactotransferrin binding indicates 1.5 X 10(13) sites per mg of membrane proteins with an equilibrium constant of 1.2 X 10(6) M-1. Sodium dodecyl sulfate solubilization of the brush-border proteins allows the lactotransferrin receptor to retain its binding activity. Moreover, the ligand blotting of the detergent solubilized membrane proteins on nitrocellulose sheet and after incubation with 125I-labeled lactotransferrin, has shown that the receptor is a protein of about 100 kDa. In the same experimental conditions, the rabbit microvillous membrane vesicles do not specifically bind rabbit serotransferrin indicating the absence of serotransferrin receptors at the brush border.

Complex structure of human bronchial mucus glycoprotein

Human bronchial mucus glycoproteins or mucins were isolated from the sputum of two patients by a method avoiding reducing agents and involving water extraction and gel filtration on Sepharose CL-2B in 6 M guanidinium chloride. The chemical analysis indicated approximately 25-40% lipid. The amino acid and carbohydrate analysis differ quantitatively from that of mucins purified after prior reduction of mucus. These fractions also have a higher proportion of aspartic and glutamic acids than that of the mucins from reduced sputum. These mucins are still contaminated by small amounts of peptides but do not seem to contain disulfide-attached cross-linking protein. Human bronchial mucins have a strong tendency to form aggregates except in 6 M guanidinium chloride. Electron microscopy performed with various procedures indicates the presence of both micelles and flexible threads measuring 200-1000 nm. Delipidation removes most of the micellar forms. Thereafter mucins appear mainly as polydisperse flexible extended threads and also as aggregates. These features of bronchial mucins do not fit with the generally accepted idea of mucin subunits linked by disulfide bridges (unless they are linked end to end) and alternatively favour a model where mucin molecules behave like filaments that could easily aggregate according to the solvent system (mucin concentration, absence of dissociating conditions).

Comparative study of the DNA-binding HU-type proteins from slow growing and fast growing strains of Rhizobiaceae

The DNA-binding HU-type proteins have been isolated from two very different strains of Rhizobiaceae : Agrobacterium tumefaciens and Rhizobium japonicum. These proteins have been called HAt and HRj respectively. Their electrophoretic mobility on polyacrylamide gel, amino acid composition and crossed immunoreactivity have been compared to that of the homologous protein isolated from Rhizobium meliloti: the protein HRm . The proteins HAt and HRm show close similarities whereas the protein HRj differs markedly from the two others. The physico-chemical characteristics of the HU-type proteins from these Rhizobiaceae are in good agreement with the respective position of these bacteria in the taxonomy.

The origin and composition of multiple forms of dextransucrase from Streptococcus sanguis

Multiple forms of purified dextransucrase have been observed in the presence of low detergent concentrations ( Luzio , G.A., Grahame , D. A. and Mayer, R.M. (1982) Arch. Biochem. Biophys. 216, 751-757). We now show these forms to arise partly as a result of proteolysis, and partly due to incomplete dissociation of the enzyme. Upon 25 degrees C incubation of the crude enzyme, several new bands appeared with little or no change in total activity. The electrophoretic pattern of aged, crude enzyme was similar to that of partially purified enzyme. Specific detection of dextransucrase on SDS gels revealed a single polypeptide of 174 kDa, which is converted to a 156 kDa protein during the aging process. The observation indicates the occurrence of proteolysis. The polypeptide composition of several of the enzyme forms was determined by two-dimensional electrophoresis. Forms Ia and IIa are composed exclusively of 174 kDa polypeptides. Forms III and IVa consist of 156 kDa units, as does the newly observed form Ic. It is likely that form Ib contains both 174 and 156 kDa polypeptides. The results indicate that incomplete dissociation of aggregates of the 174 kDa unit accounts for all of the bands observed on native gels run on fresh culture extracts. Additional enzyme forms result from aggregation of the 156 kDa proteolysis product alone, and from aggregation with unproteolyzed units to form hybrid aggregates.

Differential reduction of the inter-chain disulfide bonds of rat immunoglobulin E: relation to biological activity

Monoclonal rat IgE was reduced over a range of dithiothreitol (DTT) concns. The number of disulfide bonds reduced and their location in the IgE molecule were studied. One millimolar DTT was found to split the two inter-heavy-chain disulfide bonds of the C epsilon 2 domain while increasing DTT concn to 10 mM split the two inter-heavy-light-chain disulfide bridges. Therefore, the sensitivities to reduction of disulfide bonds in rat IgE were found to be the opposite of those in human IgE. In addition, the results indicated the absence, in rat IgE, of the intra-epsilon-chain labile disulfide bond of the C epsilon 1 domain, which is reduced by 2 mM DTT in human IgE. Circular dichroism studies showed significant modifications, mainly of tertiary structure, for rat IgE reduced with 10 mM DTT, but not for IgE reduced with 1 mM DTT. The ability to block passive sensitization with reaginic antibody was not modified when IgE was reduced with 1 mM DTT (which split the two inter-heavy-chain disulfide bonds), but was lost when inter-heavy-light-chain bridges were reduced with 10 mM DTT. In addition, a non-covalent epsilon-chain dimer was found to have the same blocking activity as native IgE (or IgE reduced with 1 mM DTT). Therefore, the results suggest that reduction of most or all the inter-chain disulfide bonds, in rat as in human IgE, induces changes in quaternary structure, more especially in the relationship between the Fab and Fc parts of the molecule, leading to steric blockade, by Fab, of the binding sites for mast cells present on Fc.

Phylogenetic studies of cardiac myosins from amphibia to mammals

Comparison between pig atrial and ventricular myosins was performed on the light chains (using SDS-PAGE) and on the heavy chains (using Ca2+-ATPase measurements and NTCBA peptide mapping). Light chain composition of pig cardiac myosins was compared to three other species ones (frog, chicken and human). Up to birds, atrial and ventricular myosin light chain composition was identical whereas in mammals atrial and ventricular myosin light chain composition was different; likewise the heavy chains. Six cardiac myosin isoenzymes have been thus characterized. No correlation can be established between cardiac myosin light chain pattern and species evolution.

Studies of an abnormal serum albumin unstable upon storage

A case of inherited bisalbuminemia was discovered in which electrophoretic controls showed that the proportion of the abnormal albumin decreased progressively during storage of the serum either at 4 degrees C or at room temperature. Such a decrease was also found when the serum was incubated with the proteolytic enzymes trypsin or plasmin. Studies with the isolated abnormal albumin showed that either during storage or after incubation with trypsin (or plasmin), its mobility became identical to that of normal serum albumin. Structural analyses showed that the albumin variant was identical to the previously described pro-albumin Christchurch that contains an additional N-terminal sequence: Arg-Gly-Val-Phe-Arg-Gln. It was therefore suggested that the progressive decrease of the abnormal albumin during storage by serum was related to the cleavage of the N-terminal abnormal sequence by plasmin already present in the serum. The decrease of the abnormal albumin during storage was inhibited by addition of cortisol to serum (1 mol per mol serum albumin). This was found related to a protective effect of cortisol bound to the albumin variant on proteolysis by plasmin.

Genetic transformation in Staphylococcus aureus: isolation and characterization of a competence-conferring factor from bacteriophage 80 alpha lysates

The competence-conferring activity in crude lysates of the staphylococcal bacteriophage 80 alpha was concentrated and purified by (NH4)2SO4 precipitation, differential ultracentrifugation and rate-zonal centrifugation through Ficoll. This concentrated preparation exhibited lytic activity toward assay cells of Staphylococcus aureus 8325-4 that could not be attributed to the residual 80 alpha infectious particles present. Electron microscopic examination of the concentrated competence-conferring activity revealed an occasional intact but empty virion and large numbers of free phage tails. Sodium dodecyl sulfate-polyacrylamide gel analysis of this material confirmed that the competence-conferring activity contained only some, but not all, of the major virion proteins. The competence-conferring activity exhibited single-hit kinetics when assay cells and 80 alpha transfecting deoxyribonucleic acid were present in excess. The competence-conferring activity thus seems to be a unique morphogenic precursor of the 80 alpha virion that mediates transfection and transformation in the presence of 0.1 M CaCl2.

Purification and characterization of alpha 1-antichymotrypsin from human pleural fluid and human serum

Human alpha 1-antichymotrypsin was purified from human pleural fluid and from human serum. Four affinity chromatographic steps were required to obtain pure alpha 1-antichymotrypsin. Pleural and serum alpha 1-antichymotrypsin have the same molecular weight, which was estimated by SDS-polyacrylamide gel electrophoresis to be 58 000. The chemical composition of the two types of alpha 1-antichymotrypsin is the same. Using a technique for visualization of the chymotrypsin inhibitors, we showed that the pure alpha 1-antichymotrypsin obtained from the two physiological fluids had its inhibitory capacity preserved.

Uniformity of carbohydrate chains within molecular variants of rat alpha 1-fetoprotein with distinct affinity for concanavalin A

Three rat alpha 1-fetoprotein fractions were obtained by chromatography on concanavalin-A--Sepharose: one non-reactive, one weakly reactive and one reactive to concanavalin A. The non-reactive and reactive variants were found to vary in the structure of their carbohydrate chains while the conformation of the weakly reactive form may modulate the accessibility of these chains to the lectin. N-Glycosidically linked glycans from unfractionated alpha 1-fetoprotein were isolated and chemically characterized. Particular attention was paid to develop sensitive methods based upon hydrazinolysis, quantitative re-N-acetylation of glycans with [14C]acetic anhydride and thin-layer chromatography of labeled compounds. With the aid of these methods two main kinds of glycans (1a and 2a) were obtained and fractionated on concanavalin-A--Sepharose into non-reactive (1a) and reactive (2a) molecules. Moreover it was demonstrated that each alpha 1-fetoprotein variant contained either two glycans 1a or two glycans 2a, not randomly, but a pair of the identical carbohydrate chains at the two glycosylation sites.

Stimulation of autophosphorylation of liver cell membrane proteins by calcium and partial hepatectomy

Partial hepatectomy in the rat stimulated the phosphorylation of three proteins (Mr 100,000, 48,000, and 35,000) in the plasma membranes of the proliferatively activated cells of the liver remnant. The autophosphorylation of these plasma membrane proteins began to rise about 8 hours after surgery, peaked at 14 hours, and then returned to the original low level by 24 hours. This increase in autophosphorylation was not evident in isolated plasma membranes from other proliferatively activated liver cells, such as those in fetal liver or hepatomas. The protein kinase responsible for the phosphorylation of the three membrane proteins was activated by calcium but appeared both cyclic-AMP- and calmodulin-independent.

Perineal rhabdomyosarcoma in a newborn child: pathological and biochemical studies with emphasis on contractile proteins

Histological and ultrastructural studies have been undertaken on a perineal rhabdomyosarcoma from a newborn child. The spontaneous tumour has the typical feature of mesenchymoma. The recurrent tumour, however, displays some rhabdopoietic characteristics. The myosin of the recurrent tumour has been extracted and compared with human fetal myosin. These two myosins are identical in their synthetic filaments and their light-chain composition. Nevertheless, whereas the ATPase activity of fetal myosin can be stimulated considerably by increasing the ca2+ concentration, that of tumoral myosin remains very low. These results show that there are isoenzymes of myosins and there must be differences in the myosin heavy chains, particularly in the active sites. These findings are identical with those seen in experimental rhabdomyosarcoma.

Complete amino-acid sequences of DNA-binding proteins HU-1 and HU-2 from Escherichia coli

The DNA-binding protein HU from Escherichia coli is a heterodimer constituted of two polypeptide chains termed HU-1 and HU-2, of 90 residues each. Their primary structures were established from structural data obtained from tryptic peptides of each monomer in addition to the structural data provided by the automated Edman degradation of the dimer and by peptides derived from cleavage of the dimer with trypsin, chymotrypsin, V8 staphylococcal protease and dilute acid. The results presented in this paper confirm the amino-terminal and carboxy-terminal sequences of the dimer HU reported previously [Laine et al. (1978) FEBS Lett. 89, 116--120]. The amino acid sequences of proteins HU-1 and HU-2 are identical to those of proteins NS-1 and NS-2 respectively, determined independently by Mende et al. [FEBS Lett. (1978) 96, 395--398]. The amino acid sequences of proteins HU-1 and HU-2 are closely related but differ by 28 residues. These proteins are characterized by their high content of hydrophobic residues represented mostly by alanine. In both proteins, half of the basic residues are scattered along the polypeptide chain and the remainder is found within two short sequences located in the carboxy-terminal part of the molecule. No sequence homology could be established between the proteins HU-1 and HU-2 and any one of the five histones from different eukaryotes.

[Partial characterization of 2 extracellular aminopeptidases (arylamidases) from the dermatophyte Keratinomyces ajelloi]

Two aminopeptidases AP1 and AP2 have been isolated from Keratinomyces ajelloi filtrates. The molecular weight is about 27 000 for AP1 and 23 000 for AP2. Both aminopeptidases present maximum activity at pH 9.35 but 50 p. 100 of maximum activity is observed between pH 7.5 and pH 8.5. Km values measured at pH 9.35 with L-leucine-p-nitroanilide as substrate are 0.38 X 10(-3) M for AP1 and 0.43 X 10(-3) M for AP2. kcat at the same pH are 63.6 sec.-1 for AP-1 and 62.8 sec-1 for AP2. Both aminopeptidases are inhibited by mercuric chloride, o-phenanthroline, dithiothreitol and 2-mercaptoethanol. Some of their characters make them similar to Streptomyces griseus pronase aminopeptidases.

Microheterogeneity of rat, mouse and human alpha1-fetoprotein as revealed by polyacrylamide gel electrophoresis and by crossed immuno-affino-electrophoresis with different lectins

Polyacrylamide gel electrophoresis and crossed immuno-affino-electrophoresis with several free lectins have been used to characterize and to compare the molecular heterogeneity of rat, mouse and human alpha1-fetoproteins. Each alpha1-fetoprotein contains a variable number of electrophoretic variants depending on the gel porosity. In SDS electrophoresis, two molecular size populations are present in rat alpha1-fetoprotein (Mr = 74 000 and 72 000) and in mouse alpha1-fetoprotein (Mr = 73 000 and 72 000) but only one is observed in human alpha1-fetoprotein (Mr = 70 000). The crossed immuno-affino-electrophoresis patterns square with affinity chromatography results and reveal a marked and characteristic heterogeneity for the three alpha1-fetoprotein species with Concanavalin A, Ricinus communis and Lens culinaris lectins. No lectin-alpha-fetoprotein interaction is apparent with Ulex, Lotus and wheat germ lectins. Since similar patterns are obtained whether with purified alpha1-fetoprotein or with unfractionated fresh fetal sera, it is likely that this heterogeneity is not a consequence of artefactual molecular modifications arising during the purification procedure.

[Isolation of myosin light chain from porcine heart by preparative electrophoresis and study of the polypeptides obtained by cyanogen bromide action]

A simple, rapid and efficient procedure is developed to isolate proteins with identical or different isoelectric points such as pig cardiac myosin light chains. Preparative electrophoresis on discontinuous polyacrylamide slab gels in the presence of urea allows a very good separation of each light chain (L27 and L18) and heavy chain from highly purified myosin. An original elution procedure of the proteins fixed and localized by amido schwartz allows the isolation of the L27 and L18 light chains in quantities sufficient to carry out structural studies. Homogeneity of light chains thus isolated is checked by the analysis of cyanogen bromide peptides. Structural similarities can be demonstrated between myosin light chains of beef and pig heart.