The tryptophan-rich keratin protein fraction of claws of the lizard Varanus gouldii

1. Claw keratin of the lizard, Varanus gouldii, is composed mainly of 13,000 mr proteins rich in glycine and cystine. This study deals with a tryptophan-rich group of about 20 constituent proteins comprising about one-third of the mass. 2. As S-carboxymethylkerateines, these proteins were separated by fractional precipitation and gel filtration, then characterized by amino acid analysis, end group analysis, electrophoresis and ultracentrifugation. 3. It is considered that the majority of lizard claw proteins are more closely allied to those of avian beak and claw than feather proteins. 4. Claw keratin also contains minor proteins which resemble mammalian keratin high-tyrosine proteins.     

Development of chicken epidermis cultured with embryo extract

The epidermis from 11-day-old chick embryo shank skin was cultured with 11-day-old chick embryo extract. The growth and the differentiation of the epidermis in culture were studied histologically, electron microscopically and with polyacrylamide gel electrophoresis of keratin proteins. The epidermis cultured with the chick embryo extract proliferated and stratum structures developed simultaneously with the increase in epidermal cell layers. Finally, a keratinized layer was observed after 10 days in culture. Electron microscopic observations revealed that tonofilaments were produced after 2 days in culture and increased thereafter with culture time, becoming condensed with desmosomes. Keratohyaline granules were observed in 7-day cultures. These keratinization characteristics occurring during culture showed the general characteristics of the alpha stratum observed in the skin of in ovo embryos during the early stages of development. However, the development of peridermal and subperidermal granules was poor and the stratum granulosum, which develops at the late stages between the stratum intermedium and the stratum corneum, was not observed. Polyacrylamide gel electrophoresis of S-carboxymethylated keratin proteins showed that the keratin protein band patterns of the culture differed from those of in ovo skin epidermis.     

AN INVESTIGATION ON KERATIN EXTRACTION FROM WOOL AND FEATHER WASTE BY ENZYMATIC HYDROLYSIS

In this study, the possibility of keratin extraction from wool and feather by an enzymatic treatment along with a reducing agent has been investigated. The effects of different parameters, that is, enzyme loading, type of substrate and surfactant, hydrolysis time, and reducing agent concentration, have been examined in order to optimize the enzymatic hydrolysis. The optimal condition for maximum keratin extraction was attained by making use of 1 g/L sodium dodecyl sulfate (an anionic surfactant) and 2.6% (v/v) protease (Savinase), along with 8.6 and 6.4 g/L sodium hydrogen sulfite (a reducing agent) for wool and feathers, respectively, at liquor to fiber ratio of 25 mL/g for 4 hr. The obtained results indicated higher degradation of wool fiber in comparison with feathers, which might be due to the higher hydrophilic nature of the former. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) patterns revealed that the molecular weights of the extracted proteins from wool and feather were lower than those for the untreated fibers. Scanning electron micrographs showed fibers fibrillation and degradation upon enzymatic treatment. Besides, Fourier-transform infrared (FTIR) spectra indicated no evident changes in the chemical structure of the hydrolyzed fibers. However, wool and feather remainders were mostly composed of α-helix and β-sheets conformations, respectively.     

Fibronectin synthesis during oogenesis and early development of the amphibian Pleurodeles waltlii

Fibronectin (FN) synthesis during oogenesis and early embryogenesis of the amphibian Pleurodeles waltlii was investigated. The isotopically labelled amino acids [3H]leucine and [35S]methionine were incubated with oocytes or microinjected into embryos. Newly synthesized FN was analysed by polyacrylamide gel electrophoresis, using the high resolution two-dimensional gel system described by O'Farrell. With this method and fluorography we demonstrate that FN synthesis begins during oogenesis. De novo synthesized FN appears during cleavage and gastrulation. Using actinomycin D we show the presence of maternal messenger RNA coding for FN. It is translated during the cleavage and gastrulation stages.     

Protein synthesis and storage in human platelets: a defective storage of fibrinogen in platelets in Glanzmann's thrombasthenia

In vivo metabolic labelling experiments were performed to investigate the ability of human platelets to synthesize and store fibrinogen and thrombospondin. Newly synthesized proteins were analyzed by SDS-polyacrylamide gel electrophoresis. Results were compared with those obtained for the platelets of a patient with Glanzmann's thrombasthenia where endogenous fibrinogen levels were severely reduced. Normal human platelets were able to synthesize the different subunits of fibrinogen and thrombospondin and to assemble them into native fibrinogen and thrombospondin molecules. This synthesis was inhibited by cycloheximide. Synthesis of both fibrinogen and thrombospondin was observed in the platelets of the Glanzmann's thrombasthenia patient. However, radiolabelled fibrinogen was no longer detected after an 18-h non-radioactive chase, although it was retained in the control platelets. Neosynthesized thrombospondin of the patient was normally preserved during the same chase period. When the fate of the radioactive fibrinogen was studied, it was found to be degraded in Glanzmann's thrombasthenia platelets to the same extent as neosynthesized cytoplasmic proteins, whereas in control platelets less degradation had occurred. We conclude that human platelets maintain a residual capacity to synthesize fibrinogen and that its deficiency in Glanzmann's thrombasthenia results from a storage abnormality and not from a synthesis defect.     

The role of β-sheets in the structure and assembly of keratins

X-ray diffraction, infrared and electron microscope studies of avian and reptilian keratins, and of stretched wool and hair, have played a central role in the development of models for the β-conformation in proteins. Both α- and β-keratins contain sequences that are predicted to adopt a β-conformation and these are believed to play an important part in the assembly of the filaments and in determining their mechanical properties. Interactions between the small β-sheets in keratins provide a simple mechanism through which shape and chemical complementarity can mediate the assembly of molecules into highly specific structures. Interacting β-sheets in crystalline proteins are often related to one another by diad symmetry and the data available on feather keratin suggest that the filament is assembled from dimers in which the β-sheets are related by a perpendicular diad. The most detailed model currently available is for feather and reptilian keratin but the presence of related β-structural forms in mammalian keratins is also noted.     

In Vitro Synthesis of the Myelin Basic Proteins: Subcellular Site of Synthesis

Abstract: Brains of 3-week-old C57BL/6J mice were homogenized and fractionated into several subcellular components, each of which was examined for ability to synthesize the myelin basic proteins (MBPs) in vitro. Myelin basic proteins were purified from incubation mixtures by conventional means. That the products of synthesis were the myelin basic proteins was established by solubility at pH 3, co-chromatography with authentic proteins on carboxymethylcellulose and co-migration with standards in two different polyacrylamide gel electrophoretic systems. The fractions examined for their ability to synthesize MBPs were the whole homogenate, postnuclear supernatant, postmitochondrial supernatant, crude mitochondrial pellet, free ribosomes and bound ribosomes. Although there was no requirement for exogenous energy sources for protein synthesis in the whole homogenate, as the homogenate was fractionated an increasing requirement emerged. Most of the label in the MBP preparations from whole homogenate and postnuclear supernatant incubations migrated with the large (L) and small (S) MBPs on gel electrophoresis; however, as the homogenate was subfractionated and incubated, a greater percentage of the label migrated more slowly than L and S on acetic acid-urea gels. To show synthesis of the MBPs the L and S bands were cut out of these gels and rerun on sodium dodecylsulfate gels. Alternatively, MBP preparations were subjected directly to two-dimensional gel electrophoresis and the bands corresponding to L and S were excised and counted. With this method only the whole homogenate, postnuclear supernatant, postmitochondrial supernatant and free ribosomes were observed to synthesize the MBPs in vitro. The "bound" ribosomes were not observed to synthesize significant amounts of the MBPs, incubated either intact or released from the membrane. It was concluded that the free ribosomes are the principal site of synthesis of the myelin basic proteins in the brain.     

Protein synthesis in germinating Saccharomyces cerevisiae ascospores

The uptake and incorporation of macromolecular precursors in germinating Saccharomyces cerevisiae ascospores were investigated. Addition of cycloheximide at various times during germination revealed that protein synthesis can occur within 20 min after the spores are shifted to glucose-containing media. The time of initiation of uptake and incorporation of several amino acids differed; this can be attributed to differing amino acid pool levels in the spores, as well as differing transport activities. Two-dimensional gel electrophoresis of proteins labeled with [35S]methionine for various 20-min periods after germination began showed at least one protein whose synthesis begins well after the bulk of the proteins.     

AN ELECTRON MICROSCOPE STUDY OF THE FINE STRUCTURE OF FEATHER KERATIN

Thin sections of the rachis of regenerating follicles of pigmented fowl feathers and of mature non-pigmented seagull feather rachis, embedded in methacrylate and Araldite respectively, were studied in the electron microscope. The late stages of development of keratin fibrils were examined in OsO₄-fixed follicle material, and after poststaining with lead hydroxide the keratin aggregates were found to be composed of fine microfibrils approximately 30 A in diameter apparently embedded in a matrix material which had absorbed the lead stain. The centre-to-centre separation of the microfibrils was of the order of 35 A. After bulk treatment by reduction with thioglycollic acid, OsO₄ staining, and poststaining with lead hydroxide, a similar microfibrillar fine structure was observed in mature rachis. Only after lead staining could the microfibrils be delineated, and their diameter and separation were similar to that found in the keratin of the follicle. It is suggested that feather keratin resembles α-keratins in consisting of microfibrils embedded in an amorphous protein matrix. However, in comparison with α-keratins, the microfibrils are much smaller in diameter, their arrangement is less orderly, and on the basis of the reactions towards the electron staining procedures, the cystine content of the matrix appears to be not greatly different from that of the microfibrils. The significance of a microfibrillar constitution of feather keratin is discussed in relation to current structural models for this fibrous protein deduced from x-ray diffraction studies. The boundaries between the component cells of feather rachis are desmosomal in character and similar to those of related keratinous structures and a number of different types of cells; the melanin granules are dissimilar to those of mammalian epidermis in their apparent lack of melanin-protein lamellae.     

Proteinases of Streptomyces fradiae. I. Preliminary characterization and purification

A keratinolytic strain of S. fradiae has been shown to synthesize a complex of extracellular proteinases degrading native keratin proteins, elastin and collagen as well as some globular proteins. These enzymes are characterized by basic optimal pH and are inactivated by pheynlmethylsulfonyl fluoride (PMSF). Using preparative polyacrylamide gel electrophoresis, ion-exchange chromatography and affinity chromatography, 6 fractions of active protein of diversified proteolytic activity have been distinguished in the preparation studied.     

Functional-morphological and biochemical correlations of the keratinized structures in the African Grey Parrot,Psittacus erithacus (Aves)

Summary Keratinized structures from the African Grey Parrot (feather, down, claw, scale, rhamphotheca, soft lingual epithelium, and lingual nail) were compard by combining biochemical and functional-morphological approaches. At the molecular level, the keratinized structures of Psittacus erithacus are organized essentially like those of other avian species. Correlations were established (or verified) between the mechanical properties of the tissues and the molecular size of the keratin monomers, between the mechanical properties and the x-ray diffraction patterns of the tissues, and between the Polyacrylamide gel electrophoresis (PAGE) patterns of the keratins and certain aspects of growth patterns of the structures. The keratin proteins of the lingual nail, described here for the first time, resemble those of the claw and rhamphotheca. Morphological, biochemical and functional differences between the lingual nail and the rest of the lingual epithelium were established.     

Nuclear matrix-intermediate filament system and its alteration in adenovirus infected HeLa cell

The nuclear matrix-intermediate filament (NM-IF) of normal and adenovirus infected HeLa cells were investigated by means of both electron microscopy and two-dimensional gel electrophoresis. After infection there were some changes in NM-IF, and the viral factory was suspended in nuclear matrix. Two new polypeptides appeared in 2-D gel of NM-IF after infection. They are probably not viral proteins but cellular polypeptides. During viral replication, all of vimentin were degraded and phosphorylated keratin 18 increased. These facts suggest that NM-IF plays a certain role in adenovirus replication.     

Gene activity during germination of spores of the fern, Onoclea sensibilis: RNA and protein synthesis and the role of stored mRNA

Pattern of 3H-uridine incorporation into RNA of spores of Onoclea sensibilis imbibed in complete darkness (non-germinating conditions) and induced to germinate in red light was followed by oligo-dT cellulose chromatography, gel electrophoresis coupled with fluorography and autoradiography. In dark-imbibed spores, RNA synthesis was initiated about 24 h after sowing, with most of the label accumulating in the high mol. wt. poly(A) -RNA fraction. There was no incorporation of the label into poly(A) +RNA until 48 h after sowing. In contrast, photo-induced spores began to synthesize all fractions of RNA within 12 h after sowing and by 24 h, incorporation of 3H-uridine into RNA of irradiated spores was nearly 70-fold higher than that into dark-imbibed spores. Protein synthesis, as monitored by 3H-arginine incorporation into the acid-insoluble fraction and by autoradiography, was initiated in spores within 1-2 h after sowing under both conditions. Autoradiographic experiments also showed that onset of protein synthesis in the cytoplasm of the germinating spore is independent of the transport of newly synthesized nuclear RNA. One-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis of 35S-methionine-labelled proteins revealed a good correspondence between proteins synthesized in a cell-free translation system directed by poly(A) +RNA of dormant spores and those synthesized in vivo by dark-imbibed and photo-induced spores. These results indicate that stored mRNAs of O. sensibilis spores are functionally competent and provide templates for the synthesis of proteins during dark-imbibition and germination.     

Usage of electrostatic eliminator reduces human keratin contamination significantly in gel-based proteomics analysis

In the field of bottom-up proteomics, heavy contamination of human keratins could hinder the comprehensive protein identification, especially for the detection of low abundance proteins. In this study, we examined the keratin contamination in the four major experimental procedures in gel-based proteomic analysis including gel preparation, gel electrophoresis, gel staining, and in-gel digestion. We found that in-gel digestion procedure might be of importance corresponding to keratin contaminants compared to the other three ones. The human keratin contamination was reduced significantly by using an electrostatic eliminator during in-gel digestion, suggesting that static electricity built up on insulated experimental materials might be one of the essential causes of keratin contamination. We herein proposed a series of methods for improving experimental conditions and sample treatment in order to minimize the keratin contamination in an economical and practical way.     

Protein synthesis in enuleated fertilized and unfertilized mouse eggs

Summary Fertilized and unfertilized C57BL/6J eggs were microsurgically enucleated and then analyzed for their capacity to synthesize proteins using 2-dimensional polyacrylamide gel electrophoresis. In both types of enucleated eggs (cytoplasts), protein synthesis continued and was still detected up to three days in culture. Shortly after enucleation, the pattern of polypeptides remained similar to the respective non-operated control eggs but it later became gradually reduced in intensity and complexity. After two days of culture the appearance of some new proteins typical for 2-cell embryos was observed in enucleated fertilized eggs only. Our findings suggest that maternal mRNA stored during oogenesis is utilized during the preimplantation period.     

Isolation of messenger RNA coding for the "fast" protein of embryonic chick feathers.

The messenger RNA coding for the "Fast" protein of embryonic chick feathers has been purified from the overwhelming relative amounts of keratin mRNA which are present in the developing feathers. The "Fast" protein mRNA represents about 4-8% of the total mRNA population of the feather. Despite differences between the size of the "Fast" proteins and the keratins the two mRNA species are very similar in molecular weight as judged by electrophoresis under denaturing conditions. However, by electrophoresis in 8 M urea gels at 55 degrees C, the "Fast" protein mRNA could be separated from keratin mRNA, presumably reflecting differences in messenger RNA secondary structure.     

Solubilization of Chicken Feather Keratin by Ammonium Copper Hydroxide (Schweitzer’s Reagent)

Chicken feather powder was solubilized by Schweitzer’s reagent with shaking in the presence of air and the soluble feather keratin was prepared by dialyzing this extract against running water. Cystine residues in the starting feather keratin was converted to cysteic acid residues in the solubilized derivatives by air oxygen. Copper was bound fairly tightly to the solubilized protein and this copper-protein complex was separated into four fractions by CM- and DEAE-cellulose column chromatography. Each fraction had varied amount of bound copper, having a broad distribution of the molecular weight between 10,000 and 60,000 Sephadex column chromatographically. Although the amino acid composition of all separated feather keratin fractions were quite similar, the different electrophoretic patterns were observed among them by DISC electrophoresis.     

Changes in Protein Composition of Three Bacterial Isolates from Marine Waters during Short Periods of Energy and Nutrient Deprivation

Two-dimensional gel electrophoresis analysis of and total cell protein determination for three bacterial isolates from marine waters at the onset and after 24 h of energy and nutrient deprivation demonstrated that the three isolates exhibited different pathways of starvation survival. Two strains appeared to synthesize new proteins during starvation.