The nuclear basic proteins of human testes and ejaculated spermatozoa

Human testicular nuclei were fractionated into two fractions according to their sedimentation in a sucrose density gradient. The nuclear basic proteins isolated from these two fractions were similar and also resembled electrophoretic mobilities and amino acid composition of the liver histones. Only quantitative differences among histone electrophoretic bands were observed. The nuclear basic proteins of ejaculated spermatozoa differed totally from those of the testes. The proteins could be divided into two categories on the basis of their electrophoretic mobilities, molecular weights and amino acid compositions. One group (SpH) was similar to testicular histones; another (HP) group was smaller, with nearly twice the electrophoretic mobility and a much higher arginine content. These proteins (HP) represent a new type of nuclear basic protein found in human tissues.     

Loss of a homologous group of proteins in a dominantly inherited ectodermal malformation.

Hair from mice bearing the dominantly inherited Naked trait (NN) and from normal (NN) mice of the same inbred strain was separated into its major protein components by standard techniques. The relative amounts of proteins in these components were then determined by a regression method from the amino acid composition of the hair samples and of the fractions into which they had been separated. The results indicated that the amount of soluble fibril in Naked-mouse hair is decreased. Polyacrylamide-gel electrophoresis of this fraction prepared from the hair of both normal and Naked mice revealed that all protein bands present in the normal are also present in the Naked mice. However, a densitometric scan of the gels at 280 nm showed that the soluble fibril fraction from Naked-mouse hair is deficient in several proteins which, on amino acid analysis, were found to contain 31% glycine and 10% tyrosine. Gel filtration of S-carboxymethylkerateine prepared from normal and mutant hair showed that the mutant hair is deficient in a heterogeneous, low-molecular-weight fraction also rich in glycine and tyrosine. Our present data do not reveal the mechanism whereby a single gene locus modulates the production of several different proteins.     

The proteins of the embryonic chick epidermis : I. During the normal development in ovo

As a preliminary to a study of the proteins of the embryonic chick epidermis when grown in vitro under various culture conditions, the proteins of the anterior metatarsal epidermis, from 11 days of embryonic life up to 9 days posthatching, have been studied. Carboxymethylated derivatives of the proteins extracted by a thiol reduction procedure have been analyzed by polyacrylamide gel electrophoresis. The results have shown that the differentiation of the epidermis is characterized by the appearance between days 14 and 17 of at least 11 major protein bands in the electrophoretic pattern. Two of these bands are of relatively high molecular weight protein and appear earlier than the remaining bands which form a group of closely related, low molecular weight protein species. The differentiation of the tissue also involves the disappearance from the electrophoretic pattern of all but one of the five major bands present in extracts of the 11/12-day epidermis. A study of the proteins derived from the isolated periderm of the 14-day chick embryo beak has suggested that one of the major bands in the 11/12-day metatarsal epidermal extracts may be a peridermal protein.     

A procedure for removal of interfering phospholipids in the separation and analysis of proteins

A procedure for removal of phospholipids from aqueous samples is described. It is simple and rapid and can be used generally in cases where phospholipids interfere with spectrophotometric, chromatographic, electrophoretic, or other methods. The procedure is based on the hydrolysis of phospholipids by phospholipase C and removal of the formed diacylglycerol by centrifugation or extraction into an inert, apolar solvent, like petroleum ether, which does not solve or have a denaturating effect on most proteins.     

Electrophoretic spectra of nuclear proteins from embryos ofXenopus laevis

Summary The changes in saline-soluble, 0.35 M NaCl-soluble and the residual fraction of nuclear proteins during early development ofXenopus were studied by analytical electrophoresis on sodium dodecyl sulfate polyacrylamide gel. The fractions were obtained by consecutive extraction of nuclei from the blastula, neurula and tail-bud stage of development. No qualitative and only limited quantitative differences were found when the proteins of any of the three fractions isolated from the neurula stage were compared with the proteins of the corresponding fraction isolated from the tail-bud stage. But the electrophoretic pattern of each of the three fractions of the nuclear proteins from the blastula stage differs significantly from the electrophoretic pattern of the same fraction isolated from the neurula or tail-bud stage. Compared with the blastula stage, in the two later stages the relative amounts of chromosomal proteins with apparent molecular weights below 30,000 are decreased. Proteins which migrate in electrophoresis in the positions of the very lysine-rich histones and of the proteins of the nuclear ribonucleo-protein particles are indicated among the chromosomal proteins of the blastula stage, and are visible as strong bands in the electrophorogram of 0.35 M NaCl-soluble proteins extracted from neurula or tail-bud stage nuclei.     

Concentrations of high-mobility-group proteins in the nucleus and cytoplasm of several rat tissues

Nuclear and cytoplasmic fractions were isolated from various tissues of the rat by a nonaqueous technique. The high-mobility-group (HMG) proteins were extracted from these fractions with acid and separated by one- and two-dimensional PAGE. The concentrations of high-mobility-group proteins HMG1, HMG2, and HMG17 in the nucleus and cytoplasm were then estimated from the staining intensities of the electrophoretic bands. The cytoplasmic concentrations of these proteins were very low--usually less than 1/30 of those present in the corresponding nuclear fractions. For the tissues studied (liver, kidney, heart, and lung), the concentrations of HMG proteins in the nucleus did not differ significantly from one tissue to another. Averaged over the four tissues investigated, there were 0.28 molecule of HMG1, 0.18 molecule of HMG2, and 0.46 molecule of HMG17 per nucleosome. These values are considerably higher than those that have been reported previously.     

Guidelines for the preparative fractionation of human serum proteins on gradient-eluted columns of concanavalin A-sepharose: elution positions of fourteen well-characterized proteins and evidence for concanavalin A-reactive albumin-IgA and -IgG complexes

Systematic studies on the fractionation of serum proteins on gradient-eluted columns of concanavalin A-Sepharose have been carried out to determine if the oligosaccharide residues were sufficiently different to permit a reasonable separation and to determine where in the chromatogram these proteins would be eluted. Human whole serum and ammonium sulfate fractions derived therefrom were used in conjunction with 2.1 x 75 cm columns of concanavalin A-Sepharose and a 4 x 400 ml gradient (Varigard) with 0.5 M methyl alpha-D-glucopyranoside as limit buffer. The elution positions and chromatographic limits of 14 well-characterized human serum proteins have been determined by double diffusion of aliquots of the effluent fractions (10X concentrated) in agarose gel against specific antibody and the general chromatographic distribution of the proteins by immunoelectrophoresis. Overall, the results demonstrate that the composition of the oligosaccharide side chain, like differences in molecular size, solubility, and charge density, is a useful parameter in the chromatographic separation of protein from serum. Although it is well-known that albumin is a nonglycoprotein, 1.0% of the protein was tightly bound by concanavalin A-Sepharose. Subsequent experiments showed that albumin binding was due to complex formation with IgA and IgG both of which possess the necessary complement of concanavalin A-reactive residues for strong binding. Sodium dodecylsulfate polyacrylamide gel electrophoresis of 2-mercaptoethanol-reduced albumin-IgA and -IgG complexes produced bands corresponding to the molecular weights of albumin and the heavy and light chains of IgA and IgG whereas unreduced samples were not dissociated. When these complexes were reacted with concanavalin A-Sepharose and treated with 2-mercaptoethanol, free albumin was eluted. The remaining adsorbed glycoprotein(s), IgA and IgG, could be eluted with methyl alpha-D-glucopyranoside. These results strongly suggest that these proteins and albumin are linked via a disulfide bond(s).     

Selective separation procedure for determination of ribosomal proteins L7 and L12.

An electrophoretic procedure for the selective separation and determination of the closely similar ribosomal proteins L7 and L12 (which are specifically involved in the GTPase reactions of the ribosome) from the total protein mixture extracted from unwashed ribosomes is described. In this procedure, which takes advantage of their unusually low isoelectric points. L7 and L12 (and a few other acidic proteins) migrate into gel asanions, while the bulk of ribosomal proteins which are basic remain behind. The positions of L7 and L12 were determined with authentic, pure proteins. It was further determined by means of 2-dimensional gel electrophoresis that no other protein components present in unwashed ribosomes comigrate with the bands of L7 and L12.     

Comparative studies of pig platelet membrane proteins

The proteins and glycoproteins of pig platelet membranes have been studied using gel electrophoretic techniques. A nomenclature is suggested from the apparent molecular weights estimated by one-dimensional electrophoresis. Isoelectric focusing showed that the majority of the proteins are in the 4.0-7.0 pH range. Subunits have been inferred from oligoproteins by two-dimensional, reduced-nonreduced, electrophoresis techniques. High resolution two dimensional electrophoresis combining isoelectric focusing and sodium dodecyl sulphate allows the observations of 60 polypeptide bands. An identification of some of those bands based on a correlation from reported human blood platelet membrane proteins is presented for comparison.     

Glucosamine-labelled envelope proteins of Escherichia coli K-12 I. Electrophoretic studies and partial fractionation of the phenol-soluble proteins

Hydrophobic envelope proteins were extracted by phenol from a glucosamine- and leucine-requiring mutant of Escherichia coli K-12 (E-110). Three protein fractions labelled with D-[1-^{1 4}C]glucosamine and L-[4,5-³H]leucine were obtained by electrophoretic separation. Envelope were isolated from cells labeleed with D-[1-^{1 4}C]glucosamine—HCL and acid hydrolyzed. At least 68% of the radioactivity was recovered as glucosamine and glucose with no random distribution of label. Fingerprinting of pronase digests of glucosamine-labelled proteins showed four radioactive spots associated with peptides. Te glycoproteins were pronase- and trypsin-sensitive and had apparent molecular weights of 11 000 (fast mobility), 35 000 (intermediate mobility) and 62 000 (slow mobility) as estimated by sodium dodecyl sulfate-polyacrylamide disc electrophoresis. The two heavier fractions were labelled with meso-diamino[1,7-^{1 4}C₂]pimelic acid, while ortho[^{3 2}P]phosphate was not incorporated into any fraction. The glucosamine radioactivity of the fast fraction underwent rapid changes upon a chase with non-radioactive glucosamine. Using a Sephadex LH-20 column, the radioactive proteins were separated from the phenol and subsequently fractionated on a DEAS-cellulose column. The DEAE-cellulose fractions were distinct from each other in the number and composition of protein bands, when analyzed by sodium dodecyl sulfate-polyacrylamide disc electrophoresis. Radioactive bands with intermediate and fast electrophoretic mobilities were found in separate DEAE-cellulose fractions.     

Micromere-specific cell surface proteins of 16-cell stage sea urchin embryos

Evidence is presented of cell-type specificity of surface proteins from the 16-cell stage sea urchin embryo. The protein composition of the micromere cell surface has been examined by 125I labelling of intact cells followed by SDS-PAGE. In Arbacia punctulata, four high molecular weight (HMW) proteins are detected on the surface of isolated micromeres--but not on mesomere-macromere fractions. In Strongylocentrotus droebachiensis, a micromere-specific protein of 133 K molecular weight (MW) was identified. This 133 K protein binds to wheat germ agglutinin (WGA) but not to concanavalin A (conA). Lectin binding was studied using a new technique. The procedure involves the separation, by SDS-PAGE, of iodinated cell-surface proteins followed by their electrophoretic transfer to lectin-coated nitrocellulose membranes. Using this procedure, cell-type-specific surface proteins which are also lectin-binding-specific, were detected.     

Studies on proteins of animal ribosomes

Summary Total ribosomal protein from rat liver ribosomes can be separated into about 20 chief electrophoretic fractions by preparative polyacrylamide gel electrophoresis. Ten electrophoretically homogeneous fractions have been isolated from the total mixture of ribosomal protein, respectively from proteins, prefractionated by CM-cellulose chromatography. Amino acid composition and molecular weights of some fractions have been determined. The amino acid composition of these fractions and of the total protein mixture are basically similar but there are also significant differences with regard to some amino acids. The molecular weights of the proteins studied are in the range between 7,000 and 29,000.     

Fractionation and characterization of normal rabbit plasma proteins

1. An adaptation of the low-temperature low-salt ethanol procedure for the fractionation of rabbit plasma proteins into six fractions is described. 2. The composition of the fractions and the distribution of haptoglobins, caeruloplasmin and transferrin were determined. The protein and protein-bound carbohydrate distribution in the fractions is similar to that of human plasma proteins separated by a similar procedure. 3. The purification of albumin, α₁-acid glycoprotein, transferrin and γ-globulin was carried out.     

A new high sensitive analytical micro-scale procedure for chromosomal proteins

Utilizing male rat liver cells we describe a method for isolating and fractionating chromosomal proteins. About 99%of chromosomal proteins was dissociated using a three step dissociation procedure. DNA was removed by sedimentation and the histone fractions were separated from the non-histone chromosomal proteins by Bio Rex 70 chromatography. The nonhistone chromosomal proteins were fractionated by micro-gradient electrophoresis on SDS-polyacrylamide gels, which proved to be superior to the electrophoretic procedures currently in use. The histones were further separated on polyacrylamide-SDS slab gels using a micro-two-dimensional electrophoretic system. The high resolution of these fractionation procedures greatly enhances the possibility of observing small changes in proteins which may play a role in gene regulation.This work was supported by the Deutsche Forschungs-gemeinschaft     

Continuous flow electrophoretic separation of proteins and cells from mammalian tissues

A new continuous flow electrophoretic separator for cells and macromolecules was built and tested in laboratory experiments and in the microgravity environment of space flight. Buffer flows upward in a 120-cm long flow chamber, which is 6 cm wide X 1.5 mm thick in the laboratory version and 16 cm wide X 3.0 mm thick in the microgravity version. Electrophoretic subpopulations are collected in 197 fractions spanning 16 cm at the upper end of the chamber. The electrode buffer is recirculated through front and back cooling chambers, which are also electrode chambers. Ovalbumin and rat serum albumin were used as test proteins in resolution and throughout tests; resolution of these two proteins at 25% total w/v concentration in microgravity was the same as that found at 0.2% w/v concentration in the laboratory. Band spreading caused by Poiseuille flow and conductance gaps was evaluated using polystyrene microspheres in microgravity, and these phenomena were quantitatively the same in microgravity as in the laboratory. Rat anterior pituitary cells were separated into subpopulations enriched with cells that secrete specific hormones; growth-hormone-secreting cells were found to have high electrophoretic mobility, whereas prolactin-secreting cells were found to have low electrophoretic mobility. Cultured human embryonic kidney cells were separated into several electrophoretic subfractions that produced different plasminogen activators; a medium-high-mobility subpopulation and a medium-low-mobility subpopulation each produced a different molecular form of urokinase, whereas a high- and an intermediate-mobility subpopulation produced tissue plasminogen activator. Canine pancreatic islets of Langerhans cells were separated into subpopulations, which, after reaggregation into pseudoislets, were found to be enriched with cells that secrete specific hormones; insulin-secreting beta cells were found in lowest mobility fractions, whereas glucagon-secreting alpha cells were found in the highest mobility fractions. Results of particle electrophoresis experiments were comparable in microgravity and in the laboratory, since cell densities that overloaded the carrier buffer (resulting in zone sedimentation) were avoided, and a 500-fold increase in protein throughput was achieved without compromising resolution in microgravity.     

Spin-labeled erythrocyte membranes: direct identification of nitroxide-conjugated proteins

The covalent incorporation of a spin-labeled analog of N-ethyl maleimide into erythrocyte membrane proteins has been monitored by electron paramagnetic resonance spectroscopy and the individually labeled proteins detected by immunoblotting techniques, using an anti-nitroxide antibody, following electrophoretic separation of the membrane components. Spin-label was primarily found in the high molecular weight bands (I and II) with no incorporation in proteins with molecular weights less than 35,000. Increasing the reaction time between the spin-label and ghosts altered both the observed labeling pattern and the epr spectra with an increase in the proportion of strongly-immobilized species.     

Isoelectric focusing of human head hair proteins. Preliminary research

The examination of human hair keratin to obtain genetic information, which may be useful also in forensic sciences, has been carried out with the use of isoelectrophoretic procedure obtaining considerable evidence for the existence of specific-species patterns. In this paper the keratins extracted from hairs of 280 subjects belonging to Sardinian people (113 males, 167 females, aged from 1 to 89, belonging to 52 families) were analyzed using IEF in thin-layer polyacrylamide gel (0.5 mm) in the pH range 2.5–7.0, followed by the silver staining method. Number, position and colour of the bands were the same in all the analyzed samples but a large individual variability was revealed for the relative intensity of some bands. Differences for a long time storage were not revealed as well hair's sample as protein extract: Neither were differences in the number and position of the bands analyzing samples of hair from several sites of the head of the same individual revealed. The results obtained are a useful indication to continue this research considering the numerous fields of application of this analysis system.     

Identification of the milk fat globule membrane proteins. II. Isolation of major proteins from electrophoretic gels and comparison of their amino acid compositions

The fat globule membranes of milk are derived from the apical plasma membrane of the mammary secretory cells. The nature of the membrane proteins, as isolated from cows' milk, has been studied by the use of discontinuous and continuous SDS-gel electrophoresis. Six methods of preparation of milk fat globule membrane suggested by various authors were tested; gel electrophoresis showed that five major bands were present, independent of the method of preparation. The apparent molecular masses of these proteins as determined on SDS-gels (15% T) were 167, 142, 64, 49 and 46 kDa, respectively. The 167 kDa band stained only with periodic acid-Schiff reagent, while the 142 kDa band stained only with Coomassie blue; the last three bands stained with both. Delipidated membranes were extracted stepwise with water, 0.02 M NaCl and 0.6 M NaCl. The 64 kDa band appears to be nearly insoluble, while the bands of 142, 49 and 46 kDa are fractionated by this procedure. The resolution of all of these proteins by electrophoresis was superior to that achieved by molecular sieve chromatography, and so electrophoretic extraction was used to isolate the major proteins. Dansyl chloride derived proteins were used as markers. Amino acid compositions of the recovered proteins were obtained and are compared.     

A Simple and Rapid Method for the Purification of Ovine Pineal Arylalkylamine N-Acetyltransferase

A two-step chromatographic procedure has been developed for the purification of ovine pineal arylalkylamine N-acetyltransferase (EC 2.3.1.87), based on the principles of disulfide exchange and anion exchange. The enzyme from 20 ovine pineal glands can be purified about 500-fold in a day; recovery is about 5%. Polyacrylamide gel electrophoretic analysis of the final preparation shows four major bands; one appears to be arylalkylamine N-acetyltransferase.     

Glucosamine-labelled envelope proteins of Escherichia coli K-12 II. Location in inner and outer membranes

Hydrophobic envelope proteins were extracted by phenol from a glucosamine- and leucine-requiring mutant of Escherichia coli K-12 (E-110). Three protein fractions labelled with D-[1-^{1 4}C]glucosamine and L-[4,5-³H]leucine were obtained by electrophoretic separation. Envelope were isolated from cells labeleed with D-[1-^{1 4}C]glucosamine—HCL and acid hydrolyzed. At least 68% of the radioactivity was recovered as glucosamine and glucose with no random distribution of label. Fingerprinting of pronase digests of glucosamine-labelled proteins showed four radioactive spots associated with peptides. Te glycoproteins were pronase- and trypsin-sensitive and had apparent molecular weights of 11 000 (fast mobility), 35 000 (intermediate mobility) and 62 000 (slow mobility) as estimated by sodium dodecyl sulfate-polyacrylamide disc electrophoresis. The two heavier fractions were labelled with meso-diamino[1,7-^{1 4}C₂]pimelic acid, while ortho[^{3 2}P]phosphate was not incorporated into any fraction. The glucosamine radioactivity of the fast fraction underwent rapid changes upon a chase with non-radioactive glucosamine. Using a Sephadex LH-20 column, the radioactive proteins were separated from the phenol and subsequently fractionated on a DEAS-cellulose column. The DEAE-cellulose fractions were distinct from each other in the number and composition of protein bands, when analyzed by sodium dodecyl sulfate-polyacrylamide disc electrophoresis. Radioactive bands with intermediate and fast electrophoretic mobilities were found in separate DEAE-cellulose fractions.