Kinds Of Polypeptides Research Articles

Innovative Design Strategy and Research Progress of Anti Human Papilloma Virus Infection Agents

This review summarized the mechanism of a novel fusion protein (PHPV fusion protein) containing membrane penetrating peptide and oligopeptide-1 (EGF). The new PHPV fusion protein contains two kinds of polypeptides: membrane penetrating peptide and oligopeptide-1, so it has a good function of preventing and treating HPV virus. PHPV fusion protein not only has the multi effect function of membrane penetrating peptide and oligopeptide-1, but also the negative charge (anion) C-terminal of the cross-linked and fused new protein surface interacts with the positive charge (cation) N-terminal on HPV particles. Through the combination of the N-terminal of the positive charge on its surface with the negative charge of the hydrophobic region in the middle and the C-terminal of the recognition region site containing peptidase, the membrane translocation signal is coupled with the NLS of the nuclear localization signal, thus blocking the invasion of human papillomavirus into host cells. Through the interaction of cell membrane, it can penetrate the natural barrier of cell membrane and play a role in destroying the viral membrane shell to inactivate the virus, so as to prevent cervical precancerous lesions and treat HPV infection. PHPV fusion protein can repair damaged cells, enhance the elasticity of loose vaginal mucosa, tighten the inner wall of the vagina, improve the vaginal wetness, and reduce the vaginitis reaction.

Purification, characterization, and mode of action of Paracin 54, a novel bacteriocin against Staphylococci.

Staphylococci belong to conditionally pathogenic bacteria, and the pathogenicity of Staphylococcus aureus is the strongest among them. Enterotoxin produced by it can contaminate food and cause food poisoning. Bacteriocin is a kind of polypeptide with antibacterial activity synthesized by some bacteria during metabolism. In this study, we report on purification, characterization, and mode of action of the bacteriocin named Paracin 54, produced by Lactobacillus paracasei ZFM54. Paracin 54 was purified by precipitation with 80% ammonium sulfate, strong cation-exchange chromatography, G-25 gel column, and reversed-phase high-performance liquid chromatography (HPLC). The molecular weight of Paracin 54 (5718.1843Da) was determined by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Paracin 54 showed broad-spectrum inhibitory activity. It had a strong inhibitory effect on Staphylococci with minimum inhibitory concentration values of 3.00-4.50μg/mL. Paracin 54 was heat-stable and active only in acidic pH range (2-6). After treatment with proteases, the activity was lost. The results of mode of action showed Paracin 54 damaged the cell membrane and cell wall of Staphylococcus aureus, and then the cytoplasm leaked out, leading to death of the bacteria. These properties make Paracin 54 a promising candidate to prevent the growth of spoilage bacteria and control food poisoning caused by Staphylococci. KEY POINTS: • Paracin 54 was purified from Lactobacillus paracasei ZFM54 with good biochemical characteristics. • Paracin 54 had a strong effect against Staphylococci, making it a promising preservative to prevent the growth of Staphylococci in food. • The mode of action of Paracin 54 on Staphylococcus aureus was revealed.

Identification of in vitro angiotensin‐converting enzyme and dipeptidyl peptidase IV inhibitory peptides from draft beer by virtual screening and molecular docking

Hypertension and diabetes are two kinds of senile diseases which often occur simultaneously. The commonly used drugs in clinic may produce certain side effects. Food-derived polypeptide is a kind of polypeptide with great development potential, which has many functions of regulating human physiological function. Beer is rich in nutrition but there are few researches on bioactive peptides in beer. In this study, a rapid virtual screening method was established to obtain bioactive peptides from Tsingtao draft beer. The peptide sequence was analyzed by ultra-performance liquid chromatography-quadrupole-Orbitrap-tandem mass spectrometry (UPLC-Q-Orbitrap-MS2 ), and 50 peptides were identified. Eight peptides with potential biological activities were screened by using Peptide Ranker software and previous literature references. On the basis of absorption prediction, toxicity prediction, and molecular docking analysis, LNFDPNR and LPQQQAQFK were finally confirmed. The molecular docking results showed that two peptides could bind angiotensin-converting enzyme (ACE) and dipeptidyl peptidase IV (DPP-IV) tightly by hydrogen bonding and hydrophobic interaction. The in vitro activity evaluation results showed that two peptides had obvious ACE and DPP-IV inhibitory activity. This study established a method for rapidly screening bioactive peptides from Tsingtao draft beer, screened two ACE and DPP-IV inhibitory peptides in beer and analyzed their active action mechanism. This article may have great theoretical significance and practical value to further explore the health function of beer. © 2021 Society of Chemical Industry.

Target-Selective One-Way Membrane Fusion System Based on a pH-Responsive Coiled Coil Assembly at the Interface of Liposomal Vesicles

The coiled coil trimer structure is a common motif observed in membrane fusion processes of specific fusion proteins such as the hemagglutinin glycoprotein. The HA2 subunit in the hemagglutinin changes its conformation or geometry to be favorable to membrane fusion in response to endosomal weakly acidic pH. This pH responsiveness is indispensable to an artificial polypeptide-triggered delivery system as well as the membrane fusion reaction in biology. In this study, we have constructed an AAB-type coiled coil heteroassembled system that is sensitive to weakly acidic pH. The heterotrimer is formed from two kinds of polypeptides containing an Ala or a Trp residue at a hydrophobic a position, and it was observed that the Glu residue at the other a position induced an acidic pH-dependent conformational change. On the basis of this pH-responsive coiled coil heteroassembled system, a boronic acid coupled working polypeptide for the combination of an intervesicular complex with a sugarlike compound on the surface of the target liposome, and a supporting polypeptide for the construction of a pH-responsive heterotrimer with the working polypeptide were designed and synthesized. The process of membrane fusion was characterized by lipid-mixing, inner-leaflet lipid-mixing, and content-mixing assays. The target selective vesicle fusion is clearly observed at a weakly acidic pH, where the working polypeptides form a heterotrimeric coiled coil with the supporting polypeptides in a 1:2 binding stoichiometry and the surfaces between pilot and target vesicles come into close proximity to each other.

Silk fibroin as a sorbent for on-line extraction and preconcentration of copper with detection by electrothermal atomic absorption spectrometry

Silk fibroin is a kind of polypeptide with functional amino acids in its structure. The electric charges in its molecular chains originating from the dissociation of acidic groups, i.e., hydroxyl, phenol and carboxyl, provide vast potentials for the retention of metal species of interest. In this study, the selective retention of Cu 2+ with silk fibroin at pH 6.0 was investigated and a novel on-line procedure for separation/preconcentration of Cu 2+ from complex sample matrices was thus developed by using a sequential injection system with an electrothermal atomic absorption spectrometry. A novel concept of enrichment index (EI), i.e., defined as enrichment factor (EF) obtained by consuming unity of sample volume (ml), was proposed for evaluating the enrichment efficiency of a flow-based preconcentration procedure. With a sampling volume of 900 μl, an EI of 30.3 (EF = 27.3) was achieved, which was much improved as compared to that of reported procedures. A detection limit of 8.0 ng l −1 was achieved within a linear range of 0.025–1.5 μg l −1 along with a precision of 2.2% R.S.D. at 0.5 μg l −1. The practical applicability of this procedure was validated by analyzing a certified reference material of riverine water (GBW08608) and a certified reference material of seawater (NASS-5) achieving satisfactory agreements between the certified and the obtained values. A spiking recovery was also performed by using a cave water sample.

Lanthanide Ion-Induced Folding of De Novo Designed Coiled-Coil Polypeptides

Abstract To construct a novel isoleucine zipper polypeptide that undergoes a random to coiled coil transition upon lanthanide ion binding, we designed a 37-residue polypeptide (Pep3) with a γ-carboxy glutamic acid (γ-Gla) as metal binding site. Pep3 was designed based on the sequence of the isoleucine zipper polypeptide (Pep1), forming a triple-stranded coiled coil. The coiled-coil structure was destabilized by ionic repulsions among γ-Gla residues at position 21 (hydrophobic 3a position) of one strand. On the other hand, a stable coiled coil formed in the presence of Eu3+ ions. This structural change in the designed polypeptide was selective toward Eu3+ ion from the circular dichroism (CD) measurements. Furthermore, we designed a lanthanide ion-induced heterotrimeric coiled-coil-assembled system by using two kinds of polypeptides, Pep4 and Pep5. CD spectroscopy, sedimentation equilibrium centrifugation, gel filtration, and HPLC analyses indicate that Pep4 and Pep5 could noncovalently assemble in a 1:2 ratio in the presence of Eu3+ ions.

Symmetry Types, Systems and Their Multiplicity in the Structure of Adenovirus Capsid

Each of the more than 1500 polypeptide molecules of 7 different types building up the adenovirus capsid--probably even those of their amino-acids--are in symmetrical location. Every kind of polypeptide forms a separately also symmetrical network in the capsid distributed according to their functions in the inner and outer side and the inside of the facets and edges, but always in compliance with the icosahedral symmetry. Therefore, each different polypeptide also means a general symmetry motif in the capsid in its own symmetry network. Hexons can be considered as general symmetry motifs in some special association that is because of their environmental position four kinds of hexon types can be found, which are on every facet, next to one another, like three identical groups of four (GOF) according to the three-fold rotational symmetry. Two polypeptides of a peripentonal hexon of each GOF orient toward the penton and the third toward the other penton located further on the same edge. There are two versions of the arrangement of the GOFs: the hexons surround either a polypeptide IX or a polypeptide IlIa. The two versions of GOFs on 20 facets symmetrically recurring 60 times as general hexon symmetry motifs form the capsid in combination with the network of other polypeptides. Ideally, the surface of the hexon trimer shows three-fold rotational and three-fold reflexional symmetries. In the arrangement of hexons in the facets the translational, rotational, horizontal and vertical reflexional symmetry and the combination of these, as well as the glide reflexion and the antisymmetry can be found. Each hexon has six nearest neighbours and every hexon takes part in the construction of three hexon rows. Every facet and every vertex made up of five facets has an antisymmetrical pair located on the opposite side of the capsid. Every triangular facet participates in forming three vertices and every facet has three nearest neighbouring facets. In the facets, the polypeptide subunits of polypeptide IX centered GOF hexons have identical counter-clockwise orientation but the orientation of the neighbouring facets is always opposite compared to each other. On the five-fold symmetry axis, any facet can be "turned on" to the adjacent facet or "rotated" to all the others and will take the symmetry and orientation of the facet it got turned on or rotated to. Thus, every facet together with the polypeptides attached to it shows a twenty-fold symmetry and multiplicity. An other type of symmetry and multiplicity in the capsid is that perpendicular to the 6 five-fold rotation axes run a geodetic (equatorial) ribbon like motif (superfieces) altogether six made up of 10 x 10 triangular facets and bent ten-times with an angle of 36 degrees. A triangular facet participates in forming three ribbon-like motifs, which intersect with each other on the given facet, but the same three motifs intersect repeatedly only on the antisymmetrically located facet.

Identification of postoperative adjuvant chemotherapy responders in non‐small cell lung cancer by novel biomarker

Cisplatin-based (CDDP-based) adjuvant chemotherapy of non-small cell lung cancer (NSCLC) was reported to yield 5-15% improvement in 5-year survival compared to complete resection alone. The importance of information concerning preselection of good responders has become increasingly evident. The purpose of our study is the establishment of a preselection of good responders for CDDP-based adjuvant chemotherapy. We investigated protein expressions comparing intensity between parent strains (H69 and PC14 lung cancer cultured cells) and resistant strains against CDDP using 2-dimensional polyacrylamide gel electrophoresis (2-DE). Immunohistochemically, we evaluated the relationship between protein expression associated with CDDP-resistance and the clinical effects of platinum-based postoperative adjuvant chemotherapy using 126 surgically-resected NCLC materials. We detected 2 kinds of polypeptides that changed expression levels on 2-DE gels. The analyses of the amino acid sequence showed that these polypeptides were reticulocalbin (RCN) and glutathione-S-transferase-pi (GST-pi). The 2-DE analysis showed decreased expression in RCN and overexpression in GST-pi with the acquisition of CDDP-drug resistance. RCN-transfectant of H69 CDDP-resistant strain showed intermediate sensitivity between the parent strain and the CDDP-resistant strain. RCN-positive cases showed a statistically significant better disease-free survival only in the cases receiving postoperative platinum-based adjuvant chemotherapy after curative resection (p = 0.007). In addition, cases that were both RCN-positive and GST-pi-negative showed a statistically significantly better outcome (p = 0.0150). In the cases without postoperative adjuvant chemotherapy no relationship between the outcome and these expressions was seen. The evaluation of RCN and GST-pi might provide valuable information concerning postoperatively therapeutic strategy from the standpoint of individualized postoperative therapy.

Purification of ferredoxins and their reaction with purified reaction center complex from the green sulfur bacterium Chlorobium tepidum

Four ferredoxin (Fd) fractions, namely, FdA–D were purified from the green sulfur bacterium Chlorobium tepidum. Their absorption spectra are typical of 2[4Fe–4S] cluster type Fds with peaks at about 385 and 280 nm and a shoulder at about 305 nm. The A385/A280 ratios of the purified Fds were 0.76–0.80. Analysis of the N-terminal amino acid sequences of these Fds (15–25 residues) revealed that those of FdA and FdB completely agree with those deduced from the genes, fdx3 and fdx2, respectively, found in this bacterium (Chung and Bryant, personal communication). The N-terminal amino acid sequences of FdC and FdD (15 residues) were identical, and agree with that deduced from the gene fdx1 (Chung and Bryant, personal communication). The A385 values of these Fds were unchanged when they were stored for a month at −80°C under aerobic conditions and decreased by 10–15% when they were stored for 6 days at 4°C under aerobic conditions, indicating that they are not extremely unstable. In the presence of Fd-NADP+ reductase from spinach, and a purified reaction center (RC) preparation from C. tepidum composed of five kinds of polypeptides, these Fds supported the photoreduction of NADP+ at room temperature with the following Km and Vmax (in μmol NADP+ μmol BChl a−1 h−1): FdA, 2.0 μM and 258; FdB, 0.49 μM and 304; FdC, 1.13 μM and 226; FdD, 0.5 μM and 242; spinach Fd, 0.54 μM and 183. The Vmax value of FdB was more than twice that previously reported for purified RC preparations from green sulfur bacteria.

Substrate-induced formation of a recognition structure in a four-polypeptide-lipid monolayer system

Poly(γ-methyl L-glutamate)s with Ser, His, Asp, and Glu residues at the amino terminal as the serine protease catalytic site were prepared. The number-average degree of polymerization of the polypeptides was 51. A dipalmitoylphosphatidylcholine monolayer containing the polypeptides was formed at the air–water interface and was transferred onto gold-deposited glass plates. The binding of N-acetyltyrosine ethyl ester, a typical substrate of the serine protease, to the monolayer was characterized by surface plasmon resonance measurements. The four-polypeptide–lipid monolayer system conditioned on an aqueous solution containing the substrate N-acetyltyrosine ethyl ester exhibited Langmuir-type binding of the substrate. Its binding constant of 6.1 × 104 M−1 was about 20 times larger than that observed for a monolayer prepared on pure water. The behavior may have arisen from a substrate-induced rearrangement of the four kinds of polypeptides in the monolayer, forming a substrate-binding structure similar to that found in serine protease. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2186–2191, 2000

Different kinds of polypeptides and polypeptide-coated nanoparticles are accepted by the selective transcytosis shown in the rabbit nasal mucosa

The specific transcytosis of polypeptides, demonstrated in the nasal respiratory mucosa of the rabbit, seems to be involved in antigen sampling at the airway entry, since absorption has been shown only to occur if lymphoid aggregates are present beneath the epithelium and to be proportional to aggregate volume. Nanoparticles and many polypeptides besides the two previously tested (i.e. carbocalcitonin (CCT) and adrenocorticotropic hormone) should be transportable, in agreement with the vesicular transcytosis and antigen sampling hypothesis. Thus unidirectional mucosa-submucosa and opposite fluxes ( J ms, J sm) and the corresponding net fluxes ( J net) of uncoated or polypeptide-coated polystyrene nanospheres (diameter: about 0.5 μm) have been measured with the aid of spectrophotometry and quantitative dark-field microscopy. No net transport has been observed for uncoated beads, whereas it has always been shown for polypeptide-coated beads, although to different extents. The selectivity sequence for the polypeptides tested is as follows: BSA≅enkephalin≪anti-BSA IgG≅IgA≅CCT≅insulin≤anti-insulin IgG. With the exception of BSA and enkephalin-coated beads, whose J net is very small, in all the other cases the apparent affinities for receptors seem to be equal or similar; just over 6% polypeptide coating on the nanosphere is sufficient to elicit maximal transport; finally, transport seems to require many cooperating binding sites between the single nanosphere and receptors or one or many non-cooperating binding sites, but with a threshold number of polypeptide molecules adsorbed on the nanosphere to reach a minimal binding probability.

Physicochemical Properties of Aggregates of Globin Hydrolysates

Globin is an edible protein that is obtained in large quantity from animal blood. It can be used as an ingredient in a variety of meat products. However, globin showed a rather low solubility at neutral pH and little advantage compared with other proteins used in the food industry. The effective use of latent materials is an important research area in food science. This study succeeds in improving globin's functional properties and explaining the mechanism of gel formation. The hydrolysis of globin was performed with 0.8 M citric acid. The globin hydrolysates showed eight bands by tricine−SDS−PAGE having molecular masses that ranged from 5000 to 15 000 Da. The results of gel filtration chromatography indicated that the large aggregates were formed easily in the case of the globin hydrolysates. Physicochemical properties of aggregates of globin hydrolysates were studied by light scattering measurement and transmission electron microscope. It is clear that the aggregates were composed of two kinds of polypeptides, one of which, the β-chain, originated from the native globin and another, β-1, originated from the β-chain by cleavage between 99 (Asp) and 100 (Pro) of the β-chain through noncovalent bonding. By comparison with the position of standard protein (thyroglobulin, MW 669 000 Da), the molecular mass of the aggregate was estimated as above 700 000 Da. The aggregates of globin hydrolysate in solution approximated the thin rod-shaped model and had lengths of 130−140 nm by light scattering measurement. Electron micrography also showed the aggregates to consist of the thin rod aggregates. The molecular mass of the aggregates was determined to be 870 000 Da by light scattering measurement, indicating that the aggregate consists of 33−34 units because each unit was in the ratio of 1:1 complex of β-chain and β-1 with molecular masses of 16 000 and 10 900 Da, respectively. Keywords: Globin; globin hydrolysates; aggregates; light scattering; tricine−SDS−PAGE

Reconstitution of Fragmentary Form of Thermostable Alanine Racemase

The fragmentary form of alanine racemase from Bacillus stearothermophilus is composed of two sets of two different polypeptides corresponding to the two domains of the subunit of wild-type enzyme. It was denatured with 6 M guanidium hydrochloride to be separated into pieces, and renatured by dilution with about 50% recovery of the activity. The two kinds of polypeptides (i.e., large and a small fragments) were isolated by gel filtration in the presence of 4 M guanidium hydrochloride. The CD spectra obtained by summation of the spectra of the refolded fragments were closely similar to that of the native fragmentary enzyme. The lysine residue to which PLP is bound in the wild-type enzyme occurs in the large peptide of the fragmentary enzyme containing the amino terminus of the wild-type enzyme. The visible spectrum of the large peptide refolded, however, indicated that PLP was not bound to it. The large peptide alone had no significant activity, but it was activated by incubation with the small peptide. Accordingly, co-existene of both peptide fragments is necessary for folding of a complex of the two kinds of peptide to form an active structure.

A novel enzymatic dehalogenation of (R)-3-chloro-1,2-propanediol inAlcaligenes sp. DS-S-7G

The mechanism of the novel enzymatic dehalogenating action of (R)-3-chloro-1,2-propanediol [monochlorohydrin (MCH)] was investigated. The (R)-MCH-dechlorinating enzyme system ofAlcaligenes sp. DS-S-7G, which stereoselectively assimilated (R)-MCH from the racemate, was composed of two components (Enzyme 1 and Enzyme 2). Enzyme 1 was a flavoprotein with a relative molecular mass (M r) of 70,000 and was composed of two kinds of polypeptides (58,000 and 16,000). The enzyme exhibited activity for converting (R)-MCH to hydroxyacetone with the liberation of chloride ions under aerobic conditions. On the other hand, Enzyme 2 with anM r of 86,000, which was also composed of two kinds of polypeptides (33,000 and 53,000), showed no dechlorinating activity for (R)-MCH. However, in the presence of NAD+, when Enzyme 1 was conjugated with Enzyme 2 in the (R)-MCH-dechlorinating reaction, the co-operative dechlorinating activity was four to five times higher than that by Enzyme 1 alone. (R)-MCH was finally degraded to acetic acid and formic acid by the joint action of the two enzymes. These facts indicate that (R)-MCH is oxidatively dechlorinated by the two enzymes in the presence of NAD+ inAlcaligenes sp. DS-S-7G.

An endosymbiont chaperonin is a novel type of histidine protein kinase.

Symbionin, a GroEL homologous molecular chaperone produced by an intracellular symbiont of the pea aphid, is able to transfer its high-energy phosphate bond to other compounds through its autophosphorylation. When the urea-dissociated monomeric symbionin fixed onto a polyvinylidene difluoride membrane was incubated with [gamma-32P] ATP, it was efficiently phosphorylated at elevated temperatures. The autophosphorylated monomeric 32P-labeled symbionin, when incubated with ADP, transferred a significant portion of its radioactivity to ADP, suggesting that the autocatalytically phosphorylated monomeric symbionin contains high-energy phosphate bonds. It was also shown that when symbiotic proteins were electrophoretically separated, blotted onto a polyvinylidene disulfide membrane and incubated with 32P-labeled symbionin, radioactivity was found on several kinds of polypeptides, indicating that the phosphoryl group was transferred from symbionin to other symbiotic proteins. Peptide sequence analysis and thin-layer chromatographic analysis of the 32P-labeled tryptic fragment of the phosphorylated symbionin revealed that the site of phosphorylation is His-133. These results suggested that symbionin functions as a histidine protein kinase, or a sensor molecule, of the two-component pathway known in other organisms. However, symbionin is not similar in amino acid sequence to any known histidine protein kinase.

Isolation of prokaryotic V0V1-ATPase from a thermophilic eubacterium Thermus thermophilus.

The soluble ATPase purified from an aerobic thermophilic eubacterium, Thermus thermophilus, was not a usual F1-ATPase but a V1-ATPase, a peripheral section of plasma membrane V-type ATPase (Yokoyama, K., Oshima, T., and Yoshida, M. (1990) J. Biol. Chem. 265, 21946-21950). Here, we report the purification of V-type ATPase from the same bacterium (V0V1-ATPase) which consists of V1-ATPase and a membrane-integrated section, V0. The V0V1-ATPase, either in the Triton X-100-solubilized membrane fraction or in the purified state, migrates as a single band in a non-denaturing polyacrylamide gel electrophoresis for membrane protein complexes, and eight kinds of polypeptides are found when this band is developed in a second dimension denaturing gel electrophoresis in the presence of sodium dodecyl sulfate. The 66-, 56-, 30-, and 12-kDa polypeptides are the subunits of V1-ATPase and the 100-, 38-, 24-, and 13-kDa polypeptides are candidates for V0 (or V0-associated) subunits. The amino-terminal amino acid sequences of the 38- and 24-kDa subunits do not show obvious similarity to any subunits of eukaryotic V0V1-ATPases. The kinetic properties of the purified V0V1-ATPase are very similar to those of V1-ATPase: a very low ATPase activity, stimulation by bisulfite, inhibition by nitrate, and resistance against inhibitors of eukaryotic V-type ATPases, Bafilomycin A1 and N-ethylmaleimide. The V0 vesicles prepared from reconstituted V0V1-ATPase vesicles by 6 M urea treatment show the H+ channel activity. This H+ channel activity is abolished either by treatment of vesicles with dicyclohexylcarbodiimide or by the back addition of V1-ATPase. These results indicate that the coupling ion of this V0V1-ATPase is H+.

SOLUBILIZATION, ELECTROPHORETIC CHARACTERIZATION AND IN VITRO DIGESTIBILITY OF ALMOND (PRUNUS AMYGDALUS) PROTEINS,2

ABSTRACTThe major U.S. marketing varieties of almonds contained moisture, protein, fat, and ash in the range 4.35–5.86%, 16.42–22.17%, 53.59–56.05%, and 2.69–2.93%, respectively. Two fatty acids, oleic (range 52.44–67.07%) and linoleic (range 22.05–38.67%) accounted for up to 90% of the total fat. The majority of almond proteins (≥ 95%) are water soluble with a minimum solubility at pH ≤ 4.0. Sodium chloride (1.0 M) decreased the almond protein solubility in aqueous medium. Electrophoretic analyses indicated that one water soluble protein dominates the almond protein composition. This oligomeric major protein is made up of two kinds of polypeptides (molecular weight range 20,000–22,000 and 38,000–41,000) linked via disulfide bonds. Among the proteases tested, pepsin was the most efficient in hydrolyzing the almond proteins.

Differences between Heat-Bleaching and Heat-Shock at the Level of Protein Synthesis in Euglena gracilis

I investigated whether heat-shock and heat-bleaching in Euglena gracilis (Klebs) z strain (Pringsheim) involve a similar response to treatments at elevated temperatures. Using pulse-labeling in vivo , I studied similarities and differences in the kinds of polypeptides that are synthesized at 33 °C (bleaching temperature) and at 36 °C (heat-shock). Although brief treatments at the bleaching and heat shock temperatures initially increase the synthesis of a similar set of major polypeptides, the similarities are limited to the first hour of incubation. Longer periods of incubation at the two temperatures result in significant differences in the synthesis of maj or polypeptides. Unlike other plant systems, a significant increase in the synthesis of polypeptides in the low molecular weight range (15,000 to 30,000 Dal) was not detected at the elevated temperatures. I report that bleaching and heat-shock probably represent different responses to temperature.

Purification and Properties of Halobacterium halobium “Cytochrome aa3” Which Lacks CuA and CuB1

An a-type cytochrome was purified from Halobacterium halobium. The cytochrome showed an absorption spectrum similar to that of cytochrome aa3; it showed absorption peaks at 420 and 598 nm in the resting state, peaks at 441 and 602 nm in the reduced form, and its CO compound showed peaks at 430 and 600 nm. The cytochrome molecule was composed of only one kind of polypeptide with the molecular weight of 40,000. The cytochrome contained two heme a molecules in the molecule but no copper. The cytochrome did not show cytochrome c oxidase activity. Midpoint redox potential at pH 8.0 of the cytochrome was determined to be +0.31 V. The amino acid composition of the cytochrome resembled that of subunit I of mitochondrial cytochrome aa3. While two molecules of heme a were reduced with sodium dithionite, only one of two heme a molecules was reduced with ascorbate plus TMPD. The heme a reduced with ascorbate plus TMPD did not react with molecular oxygen or carbon monoxide, while one of two heme a molecules reduced with sodium dithionite was oxidized by molecular oxygen and combined with carbon monoxide.

Chemical composition and translation products of radish enation mosaic virus isolated in Japan.

Radish enation mosaic virus (RMV) is a member of the comovirus group, but a biochemical characterization of the group has been done only with cowpea mosaic virus (CpMV) which is the type member of the group. Therefore, the biochemical properties of other members of the group, such as RMV, are poorly understood. The present study was an attempt to analyze the nucleic acid, coat protein and gene composition of RMV. The purified RMV was fractionated into the three components (T, M and B components). B and M components were composed of two kinds of coat proteins with molecular weights of 47k and 18k daltons and contained single stranded RNAs with molecular weights of 2.0×106 and 1.6×106 daltons respectively, but T did not contain RNAs. The RNAs contained poly (A) sequences. Then, the B-RNA was in vitro translated into one polypeptide with a molecular weight of 200k daltons in the presence of zinc ions, which inhibited the protease activity. M-RNA was in vitro translated into two polypeptides with molecular weights of 115k and 105k daltons. These products in vitro translated from M and B-RNA were cleaved into eight kinds of polypeptides during incubation without the zinc ions. The results indicated that RMV might have essentially the same chemical composition and translation strategy as cowpea mosaic virus, except that the molecular weights of M-RNA and M-RNA translation products of RMV were quite different from those of CpMV.