A modified method for amino acid analysis with ninhydrin of Coomassie-stained proteins from polyacrylamide gels

Glycans of Schistosoma mansoni and keyhole limpet haemocyanin induce hepatic granulomas in vivo

Schistosoma mansoni eggs trapped in the liver of an infected host cause the major pathological manifestations of schistosomiasis. Miracidia within the deposited eggs secrete soluble egg antigens (SEA) that induce periovular granuloma formation, which may lead to severe hepatic fibrosis. Several reports have highlighted the immunomodulatory capacities of carbohydrate determinants present in the glycoproteins of SEA. These glycans contain among others the immunogenic Galbeta1-4(Fucalpha1-3)GlcNAc (LewisX) and GalNAcbeta1-4(Fucalpha1-2Fucalpha1-3)GlcNAc (LDN-DF) elements. Due to cross-reactivity with schistosomal glycan antigens, keyhole limpet haemocyanin (KLH) has been used extensively for diagnostic and therapeutic studies on schistosomiasis. In the present study, a granulomatous response with numerous eosinophils towards SEA- and KLH-coated beads implanted in the liver by mesenteric injection was observed. Immunophenotyping of these experimentally induced granulomas for cellular recruitment, chemokines, adhesion and extracellular matrix proteins revealed very close resemblance with hepatic lesions evoked by native schistosome eggs, hence demonstrating the usefulness of the bead model, in general, as well as of KLH as a model antigen to study the immunopathological mechanisms of schistosome infections. While trypsin digestion of KLH did not alter its antigenic characteristics, beads coated with SEA or KLH treated with sodium periodate to destroy the immunological properties of their carbohydrate chains, yielded only a monolayer of macrophages similar to negative control beads. Up-regulation of ICAM-1, LFA-1 and fibronectin in SEA-induced granulomas and in native and trypsinised KLH-induced granulomas indicates a major role of the carbohydrate elements of SEA and KLH in the initiation and homeostasis of the inflammatory response. These data provide new insights in the complex and multifactorial carbohydrate-dependent host-parasite immunological interactions.

Applications of the ninhydrin reaction for analysis of amino acids, peptides, and proteins to agricultural and biomedical sciences

The reaction of ninhydrin with primary amino groups to form the purple dye now called Ruhemann's purple (RP) was discovered by Siegfried Ruhemann in 1910. In addition, imines such as pipecolic acid and proline, the guanidino group of arginine, the amide groups of asparagine, the indole ring of tryptophan, the sulfhydryl group of cysteine, amino groups of cytosine and guanine, and cyanide ions also react with ninhydrin to form various chromophores of analytical interest. Since its discovery, extensive efforts have been made to apply manual and automated ninhydrin reactions as well as ninhydrin spray reagents to the detection, isolation, and analysis of numerous compounds of interest across a broad spectrum of disciplines. These include agricultural, biochemical, clinical, environmental, food, forensic, histochemical, microbiological, medical, nutritional, plant, and protein sciences. This reaction is unique among chromogenic reactions in that at pH 5.5 it results in the formation of the same soluble chromophore by all primary amines which react, be they amines, amino acids, peptides, proteins, and even ammonia. Because the chromophore is not chemically bound to the protein or other insoluble material, it is not lost when the insoluble substrate is removed by centrifugation or filtration after the reaction is completed. The visible color of the chromophore is distinctive and is generally not affected by the yellow colors present in many food, plant, and tissue extracts. Adaptations of the classical ninhydrin reaction to specialized needs in analytical chemistry and biochemistry include the use of acid, alkaline, and fluorogenic ninhydrin reagents. To cross-fertilize information among several disciplines wherein an interest in the ninhydrin reaction has developed, and to enhance its utility, this review attempts to integrate and correlate the widely scattered literature on ninhydrin reactions of a variety of structurally different compounds. Specifically covered are the following aspects: historical perspective, chemistry and mechanisms, applications, and research needs. A better understanding of these multifaceted ninhydrin reactions provide a scientific basis for further improvements of this important analytical technique.

The role of two isoenzymes of alpha-amylase of Araucaria araucana (Araucariaceae) on the digestion of starch granules during germination

Starch is the principal reserve of Araucaria araucana seeds, and it is hydrolysed during germination mainly by alpha-amylase. There are several alpha-amylase isoenzymes whose patterns change in the embryo and in the megagametophyte from the one observed in quiescent seeds (T(0)) to a different one observed 90 h after imbibition (T(90)). The objective of this research was to study the roles of two purified alpha-amylase isoenzymes by in vitro digestion of starch granules extracted from the tissues at two times of imbibition: one is abundant in quiescent seeds and the other is abundant after 90 h of imbibition. The isoenzymes digested the starch granules of their own stage of germination better, since the isoenzyme T(0) digested starch granules mainly from quiescent seeds, while the isoenzyme T(90) digested starch mainly at 90 h of imbibition. The sizes of the starch granule and the tissue from which these granules originated make a difference to digestion by the isoenzymes. Embryonic isoenzyme T(0) digested large embryonic starch granules better than small and medium-sized granules, and better than those isolated from megagametophytes. Similarly isoenzyme T(90) digested small embryonic starch granules better than medium-sized and large granules, and better than those isolated from megagametophytes. However, a mixture of partially purified megagametophytic isoenzymes T(0) and T(90) digested the megagametophytic granules better than those isolated from embryos. Studies of in vitro sequential digestion of starch granules with these isoenzymes corroborated their specificity. The isoenzyme T(90) digested starch granules previously digested by the isoenzyme T(0). This suggests that in vivo these two isoenzymes may act sequentially in starch granule digestion.

Two-dimensional electrophoresis of proteins: an updated protocol and implications for a functional analysis of the genome

The two-dimensional electrophoresis (2-DE) technique developed by Klose in 1975 (Humangenetik 1975, 26, 211-234), independently of the technique developed by O'Farrell (J. Biol. Chem. 1975, 250, 4007-4021), has been revised in our laboratory and an updated protocol is presented. This protocol is the result of our experience in using this method since its introduction. Many modifications and suggestions found in the literature were also tested and then integrated into our original method if advantageous. Gel and buffer composition, size of gels, use of stacking gels or not, necessity of isoelectric focusing (IEF) gel incubation, freezing of IEF gels or immediate use, carrier ampholytes versus Immobilines, regulation of electric current, conditions for staining and drying the gels - these and other problems were the subject of our concern. Among the technical details and special equipment which constitute our 2-DE method presented here, a few features are of particular significance: (i) sample loading onto the acid side of the IEF gel with the result that both acidic and basic proteins are well resolved in the same gel; (ii) use of large (46 x 30 cm) gels to achieve high resolution, but without the need of unusually large, flat gel equipment; (iii) preparation of ready-made gel solutions which can be stored frozen, a prerequisite, among others, for high reproducibility. Using the 2-DE method described we demonstrate that protein patterns revealing more than 10 000 polypeptide spots can be obtained from mouse tissues. This is by far the highest resolution so far reported in the literature for 2-DE of complex protein mixtures. The 2-DE patterns were of high quality with regard to spot shape and background. The reproducibility of the protein patterns is demonstrated and shown to be thoroughly satisfactory. An example is given to show how effectively 2-DE of high resolution and reproducibility can be used to study the genetic variability of proteins in an interspecific mouse backcross (Mus musculus x Mus spretus) established by the European Backcross Collaborative Group for mapping the mouse genome. We outline our opinion that the structural analysis of the human genome, currently pursued most intensively on a worldwide scale, should be accompanied by a functional analysis of the genome that starts from the proteins of the organism.

Tooth 'enamelins' identified mainly as serum proteins. Major 'enamelin' is albumin

The major enamelin protein component present in EDTA or EDTA/guanidine hydrochloride extracts of developing bovine enamel has a molecular mass of about 67 kDa; it has an amino acid composition similar to that of bovine serum albumin and reacts with polyclonal and monoclonal antibodies to albumin. Two-dimensional separation of the components in the enamelin extract by isoelectric focusing and SDS/PAGE reveal that the major approximately 67-kDa component and almost all of the minor Coomassie-staining protein components of approximately 67 kDa, as well as many of the other minor components with different molecular masses, also react with polyclonal and monoclonal antialbumin. The approximately 67-kDa band eluted after SDS/PAGE, as well as the major approximately 67-kDa spots eluted after two-dimensional separation, were found to have N-terminal amino acid sequences identical to that of bovine serum albumin. Albumin accounted for at least 70-80% of the total protein content of the enamelin extract and was essentially the only protein in the approximately 67-kDa component. The serum proteins alpha-2 HS glycoprotein, gamma-globulin and fetuin, and the proline-rich salivary protein termed P-B were also identified in the enamelin extract. The serum proteins and the salivary protein account for greater than 95% of the proteins in the enamelin extracts. Of the remaining very small amounts of non-serum or salivary protein isolated from the enamelin extracts, three minor components were isolated which had N-terminal amino acid sequences which were not similar to any known protein in the protein sequence data base and could therefore conceivably be true 'enamelins' synthesized by ameloblasts. One additional protein had the first five N-terminal amino acids and residue 8 of amelogenin, residues 6 and 7 being different from those of amelogenin. Two other very minor protein components had amino acid compositions distinct from the amelogenins and the serum proteins, but were N-terminally blocked on attempted sequencing. None of the components in the neutral soluble low-ionic-strength extract or in the 4 M guanidine hydrochloride extract, both of which consist principally of amelogenins, immunoreacted with anti-albumin or with any of the antibodies to other serum proteins and fetuin, despite the fact that the amelogenin extracts also contain non-amelogenin proteins. On the basis of the data presented, studies employing antibodies to the so-called enamelin proteins and hypotheses as to their molecular conformation, their roles as evolutionary markers, or their positive role in mineralization should be reconsidered and reviewed.

Interaction between surface protein antigens of Streptococcus mutans and human salivary components

The potential involvement of surface antigens (Ags) I/II and III of Streptococcus mutans in its adherence to salivary pellicle-coated tooth surfaces was investigated. The binding of radiolabelled Ag I/II to hydroxyapatite was increased by pretreating the mineral with human parotid saliva, and binding was maintained in the continuous presence of saliva. Binding of Ag III to hydroxyapatite was inhibited by pretreatment with, or in the presence of, saliva. Various aminohexoses, and also tris, inhibited the binding of Ag I/II. When Ags I/II and III were tested for their ability to bind to salivary components separated by SDS gel electrophoresis, several proteins capable of binding Ag I/II were identified, notably 2 proteins of apparent relative molecular mass 28,000 and 38,000. Analysis of these proteins, isolated by micro-preparative electrophoresis, indicated high proportions of proline, glycine, and glutamic acid, and overall compositions similar to basic proline-rich salivary proteins.

Comparative characterization of spirosomes isolated from Lactobacillus brevis, Lactobacillus fermentum, and Lactobacillus buchneri

Spirosomes, cytoplasmic fine spirals, were isolated and purified from Lactobacillus brevis ATCC 8287, L. fermentum F-1, and L. buchneri ATCC 4005, and their morphological, biochemical, and immunological properties were investigated. The spirosomes of these lactobacilli were morphologically indistinguishable from one another, and they had the same buoyant density of 1.320 g/cm3 in CsCl. All of the spirosomes were composed of a single protein, spirosin, with an apparent molecular weight of about 95,000 for L. brevis and L. fermentum and of about 96,000 for L. buchneri as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The spirosins from the three lactobacilli were compared by peptide mapping on SDS-PAGE after cleavage with N-chlorosuccinimide and limited proteolysis with Staphylococcus aureus V8 protease. The peptide map of the L. brevis spirosin was identical with that of the L. fermentum spirosin, whereas it was markedly different from the L. buchneri spirosin. The amino acid composition of the L. brevis spirosin was almost similar to that of the L. fermentum spirosin, while it differed appreciably from the L. buchneri spirosin. Using antiserum against the L. brevis spirosin, immunodiffusion test revealed that the antigenicity of the spirosomes from L. brevis was identical with that from L. fermentum, whereas it was partially different from that from L. buchneri.

Ontogeny of alpha-crystallin polypeptides during the lens development of a mutant mouse

The ontogeny of alpha A, alpha B and alpha Ains polypeptides of the alpha-crystallin was investigated by the indirect immunofluorescence staining method with antibodies directed against these three polypeptides in a mutant mouse strain called dyl (27). In this strain cataractogenesis starts around day 16 of lens development but the early development of the lens and the ontogeny of lens crystallins do not differ from the normal genotype (29). The polypeptides were fractionated from normal adult Swiss albino mice total native alpha-crystallin by SDS gel electrophoresis, extracted, lyophilized and injected into young rabbits for production of the antibody. The isolated polypeptides were controlled by SDS gel re-electrophoresis and the antibodies were tested against rat lens native alpha-crystallin by immunoblotting. alpha A and alpha Ains antibodies cross reacted, while alpha B did not show any cross reaction. Results presented here show that alpha A and alpha B appear simultaneously while alpha Ains was detectable at a later stage of lens development. These results are discussed.

Improved purification of pyruvate decarboxylase from wheat germ. Its partial characterisation and comparison with the yeast enzyme

An improved procedure was developed for the isolation of pyruvate decarboxylase from wheat germ. Its final step, an electrophoresis of the native apoenzyme in concave pore gradient polyacrylamide gels, followed by superficial activity-staining, produced two bands of different molecular masses and chain compositions. The high-molecular-mass band occurred in low quantity and consisted of, probably eight, apparently identical chains of Mr = 33,000, as judged from sodium dodecyl sulfate electrophoreses. The low-molecular-mass band contained two types of chains with Mr alpha = 63,000-65,000 and Mr beta = 61,000-62,000. The N termini of both chains were threonine, whereas their C-terminal sequences were different: alpha, -(Val)-(Ser)-(Ala)-Leu; beta, -(His)-(Asp)-(Ala)-Ser. Their amino acid composition was too different to be compatible with our original concept of one chain being produced from the other by proteolytic shortening. Limited proteolysis by Staphylococcus aureus V8 proteinase yielded peptides partly identical size and partly quite different. In all properties investigated, the low-molecular-mass enzyme largely resembled yeast pyruvate decarboxylase; the holoenzyme appeared to possess (alpha beta)2 structure, the apoenzyme alpha beta. SH reagents inactivated the enzyme. Binding and fluorescence of 2-p-toluidinonaphthalene-6-sulfonate indicated a similar lipophilicity of the active site as found earlier for the yeast enzyme. 2-Hydroxy-5-nitrobenzyl modification of exposed tryptophan residues left the holoenzyme intact, but in the apoenzyme it destroyed most of the cofactor-binding ability and hence the activity. The strength of cofactor binding and the maximal specific activity were found somewhat lower than in yeast pyruvate decarboxylase.

Ontogeny of alpha A and alpha B crystallin polypeptides during Rana temporaria lens development

The ontogeny and localization of alpha A and alpha B polypeptide chains of alpha-crystallin were investigated in the developing lens of Rana temporaria, an anuran amphibian, using the indirect immunofluorescence staining method with heterologous antibodies directed against these two polypeptides. alpha A and alpha B crystallins are primary gene products and are translated by different mRNAs in mammals. Although they show about 6000 amino-acid sequence homology (Bloemendal, 1977), the alpha A cDNA of rat and mouse does not hybridize to alpha B mRNA (Dodemont et al., 1981; King and Piatigorsky, 1983). Antigenically too, alpha A and alpha B polypeptides have been shown to be different. These two polypeptides were isolated from mouse lens native alpha-crystallin by SDS-gel electrophoresis and were injected into young rabbits to raise antibodies. These antibodies were tested by immunoblotting against R. temporaria total lens soluble proteins before their use in the present investigation. Results presented here show that in the developing lens of R. temporaria, alpha A appears earlier than alpha B, suggesting a differential gene activation. In addition, these two polypeptides could not be detected either in the developing lens epithelium or in the epithelium of young froglets (2-3 weeks post-metamorphosis).

Isolation and characterization of a cDNA coding for human myeloperoxidase

A cDNA encoding the carboxyl-terminal fragment of the human myeloperoxidase heavy chain was isolated and characterized. It was then used to determine the locations of the myeloperoxidase light and heavy chains in the polypeptide precursor. A cDNA library from poly(A)+ RNA from human leukemia HL-60 cells was constructed in pBR322 and screened by differential hybridization with enriched and depleted cDNA probes and then by hybridization with an oligonucleotide probe. A cDNA clone containing 1278 bp with an open reading frame of 474 bp and a 3' noncoding region of 804 bp was isolated. The amino acid sequence deduced from the nucleotide sequence consisted of 158 residues including a sequence of 14 amino acids known to be present in the heavy chain of the molecule. The cDNA also included a stop codon of TAG followed by a noncoding sequence that included a potential recognition site for polyadenylylation and a poly(A) tail. RNA transfer blot analysis with the cDNA probe indicated that myeloperoxidase mRNA was approximately 3.3 kb in length. In vitro translation of the mRNA selected by cDNA hybridization revealed preferential synthesis of a 74,000-Da polypeptide precursor that could be precipitated with anti-myeloperoxidase IgG. Antibodies specific for the heavy and light chains of myeloperoxidase were isolated from antiserum by affinity chromatography employing Sepharose columns covalently bound to the heavy or light chains. Antibodies specific for the light chain or the heavy chain readily precipitated the 74,000-Da precursor polypeptide. These results indicated that myeloperoxidase is synthesized as a single chain which undergoes processing into a light and heavy chain. Furthermore, the heavy chain of myeloperoxidase originates from the carboxyl terminus of the precursor polypeptide.

Amino acid analysis by high-performance liquid chromatography of a single stained protein band from a polyacrylamide gel

A single stained band containing approximately 5 micrograms of protein was cut out of a polyacrylamide gel and subjected to hydrolysis together with the gel. The hydrolysate was subsequently analyzed for its amino acid content by high-performance liquid chromatography and postlabeling with o-phthalaldehyde. Bovine serum albumin, ribonuclease B, ovalbumin, pepsin, and chymotrypsinogen A were analyzed by this method, and their amino acid compositions were found to be in good agreement with the reported values. By this method, it is possible to quantitate 16 amino acids: Asx, Thr, Ser, Glx, Pro, Cys, Gly, Ala, Val, Ile, Leu, Tyr, Phe, His, Lys, and Arg. Thioglycolic acid is effective protection against the decomposition of Tyr, Cys, and Met; however, the recovery of Met is inconsistent. This method might be very helpful for the amino acid analysis of proteins of multicomponent systems, especially, those which can be resolved only by polyacrylamide gel electrophoresis.

Molecular relationship between two types of phospholipase B from Penicillium notatum and reconstitution of active enzyme from its peptide fragments

Two types of phospholipase B of Penicillium notatum, the native type and the modified type that is thought to be generated by the introduction of some nicks into the native type of enzyme by the endogenous protease(s), were distinguished on a slab sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis under a nonreducing condition. The native form migrated with a rate corresponding to 95K Da, whereas the modified form migrated more slowly, corresponding to 106K Da, presumably because of its more extended conformation. That the "106K" protein was indeed a nicked product of the "95K" protein was confirmed by amino acid analysis, peptide mapping, N- and C-terminal sequence analyses, and immunoblotting. The peptide fragments (70K and 37K + 32K) comprising the modified protein were isolated by gel filtration in the presence of SDS and 2-mercaptoethanol (the 32K peptide was suggested to be a partial proteolytic product of the 37K peptide). When the "95K" protein was subjected to the same treatment under denaturing condition, it retained a low, but significant, enzymatic activity; in contrast, the separated peptide fragments did not show any significant activity. By a coincubation of these fragments, however, a restoration of enzymatic activity was observed through a reformation of the active complex, corresponding to the original modified protein. The enzymatic activity of this complex was further increased by a treatment with guanidine X HCl, followed by dialysis. The association of peptide fragments appears to occur through the formation of interpeptidal disulfide bonds.

Ontogeny of the 35K epsilon crystallin during Rana temporaria lens development

Epsilon is a recently described eye lens protein from Rana temporaria, an anuran amphibian. It is oligomeric with a subunit M.W. of 35K. The cDNA coding for 35K E- in frog lens does not show any homology with cDNA's coding for alpha-, beta-, gamma-, and delta-crystallins. Immunologically, it also does not react with antibodies directed against alpha-, beta-, and gamma-crystallins. The ontogeny of this 35K E-protein has been investigated in R. temporaria lens development by the indirect immunofluorescence staining method with an antibody specific for the 35K E-protein. The purity of the isolated 35K protein and the specificity of the antibody were controlled by Tris-SDS gel electrophoresis and immuno-blotting, respectively. The first positive immunofluorescence reaction was observed in the inner cell wall of a stage V lens. In the external layer/epithelium the reaction was first detected in a single cell of a stage VII lens. Additional positive cells in the external layer/epithelium were detected at an early state VIII and the reaction appeared to be patchy. This type of patchy reaction was also observed in the epithelium of froglet (sub-adult) eye lens.

Nerve injury stimulates the secretion of apolipoprotein E by nonneuronal cells

Nerve trauma initiates significant changes in the composition of proteins secreted by nonneuronal cells. The most prominent of these proteins is a 37-kDa protein, whose expression correlates with the time course of nerve development, degeneration, and regeneration. We now report that the 37-kDa protein is apolipoprotein E (apoE). We produced a specific antiserum against the 37-kDa protein isolated from previously crushed nerves. This antiserum recognizes a 36-kDa protein in rat serum that we have purified and identified as apoE. The anti-37-kDa antiserum also recognizes apoE on electrophoretic transfer blots of authentic samples of high and very low density lipoproteins. The nerve 37-kDa protein comigrates with apoE by two-dimensional electrophoresis, shares a similar amino acid composition, and reacts with an antiserum against authentic apoE. The purified apoE specifically blocks the immunoprecipitation of [35S]methionine-labeled 37-kDa protein synthesized by nonneuronal cells. Thus, on the basis of its molecular mass, isoelectric point, amino acid composition, and immunological properties, we conclude that the 37-kDa protein is apoE. We also used light microscopic immunohistochemistry to localize apoE following nerve injury. In rats with optic nerve lesions, the 37-kDa antiserum bound specifically to the degenerating optic tracts and to the retino-recipient layers of the lateral geniculate nucleus and the superior colliculus. We propose that apoE is synthesized by phagocytic cells in response to nerve injury for the purpose of mobilizing lipids produced as a consequence of axon degeneration.

Sequence homology analysis of proteins by chemical cleavages: using a mono and two dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis

The examination of possible sequence homology in proteins using SDS-PAGE systems after chemical cleavage is described. After SDS-PAGE, the establishment of amino acid compositions, the techniques of staining gel and five different methods of chemical cleavages (cyanogen bromide, BNPS-skatole, hydroxylamine, formic acid and nitrothiocyano benzoic acid) have been used for peptide mapping studies. Potential applications of this technique are discussed from both the biochemical and immunochemical point of view.

Ontogeny of the 38K epsilon-polypeptide during lens development of the duck Anas platyrhynchos

The epsilon-crystallin polypeptide is a recently described protein in the eye lens of the peking duck, Anas platyrhynchos. It does not cross react with alpha-, beta-, delta-, and gamma-crystallins. It has a molecular weight of 120K and consists of 3 identical 38K polypeptides. It is found in some reptiles and birds. The ontogeny of this polypeptide has been investigated in the developing A. platyrhynchos lens via the indirect immunofluorescence staining using a homologous antibody. The 38K polypeptide was extracted from 13% Tris-SDS acrylamide gels, lyophilized and injected into a young rabbit to raise an antibody. The purity of the isolated 38K polypeptide and and the specificity of the antibody were checked by Tris-SDS gel electrophoresis and immunoblotting, respectively. The first positive reaction is detected at 80 h (stage 18) incubated lens. It is confined to a few elongating early primary fibres. Until the 9th day of development the reaction is confined to the primary and secondary lens fibres. The first positive reaction in the annular pad area is observed in the "day 10" lens. In the anterior epithelium the first positive reaction is detectable in the "day 12" lens. At the beginning it is confined to a few cells in the center of the epithelium and gradually the reaction spreads to other cells. A strong and uniform reaction in the entire epithelium is noted for the first time in the lens of a just-hatched duckling. The 38K epsilon-polypeptide is detectable after the alpha-, beta-, and delta-crystallins, which, in the duck, appear simultaneously from 66 h (stage 15/16).

Recovery of native proteins from preparative electrophoresis gel slices by reverse polarity elution

A technique for high yield recovery of native, biologically active proteins from preparative polyacrylamide gel slices by reverse polarity elution is described. No apparatus other than the standard slab gel electrophoresis system is required. Several proteins have been recovered in biologically active form at a 90% yield, in quantities ranging from 0.4 mg to 4.2 mg. The method is effective with both small (9,000 dalton) and large (186,000 dalton) polypeptides. Both simple and complex proteins are recovered intact. For example, the copper-zinc and manganese superoxide dismutases from crude soybean extracts are active upon recovery. Similarly, the vitamin D-dependent calcium binding proteins from rat kidney and intestine are isolated by this method in homogeneous, active form.

Transglutaminase-catalysed incorporation of putrescine into denatured cytochrome. Preparation of a mono-substituted derivative reactive with cytochrome c oxidase

Guinea pig liver transglutaminase has been used to incorporate putrescine into horse heart cytochrome c. The native protein showed essentially no incorporation, while ethanol-denatured cytochrome c incorporated almost 1 mol putrescine per mol protein. No increase in this level of modification was obtained when maleylated cytochrome c and the tryptic peptides of cytochrome c were used as substrates. Analysis of the modified ethanol-denatured cytochrome c by tryptic cleavage and peptide isolation showed that glutamine-42 of the intact protein is the site of incorporation of radioactively labelled putrescine. Ethanol-denatured cytochrome c that was specifically modified at glutamine-42 by incorporated of putrescine could be readily renatured. The renatured modified protein showed reactivity with cytochrome c oxidase comparable to that of the original native protein.

Biochemical characterization of the cuticle collagen of the nematode Caenorhabditis elegans

Proteins of purified cuticles from adults of the small free-living nematode Caenorhabditis elegans are solubilized by reduction in the presence of a strong denaturing agent and then carboxymethylated. As in the large parasitic nematode Ascaris lumbricoïdes, these soluble proteins appeared to be collagens by their amino acid compositions. C. elegans cuticle collagen is separated into seven major components with different apparent molecular weights by molecular sieve chromatography and sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The two main components, which together account for more than 64% of the total cuticle collagen, were extracted from gel after electrophoresis and analyzed. They differ in their amino acid compositions and would seem to represent genetically distinct collagen chains. The results presented lead to the hypothesis of the presence in this collagen of at least two different chains.