Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P00790 (PGA)
 2,475 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The inhibitory specificity and stability of ovomucoid from Japanese quail egg white (OMJPQ) were examined to understand its nutritional significance. OMJPQ showed strong inhibitory activities toward trypsins from various origins including human, and the trypsin inhibitions occurred at molar ratios of enzyme to inhibitor between 1/1 and 2/1. On the other hand, an equimolar mixture of the second and third domains of OMJPQ inhibited bovine trypsin more strongly than the corresponding native OMJPQ did. This distinction was partly explained by the presence of steric hindrance on the formation of a 2:1 trypsin-OMJPQ complex. OMJPQ retained about 100% of its original activity over a pH range from 1 to 12 after a 24-h incubation at 37 degrees C. The inhibitor was most thermostable between pH 2 and 5, where more than 70% of its original activity was maintained after a 1-h incubation at 100 degrees C and about 25% of the activity even after a 30-min incubation at 121 degrees C. OMJPQ was also considerably resistant to pepsin attack. Pepsin digestion of the protein resulted in only about 40% loss of the original trypsin-inhibitory activity even after a 24-h digestion. Furthermore, the addition of bovine serum albumin to the digestion mixture brought about rapid elevation in the trypsin-inhibitory activity during an initial 30-min digestion. SDS-PAGE and immunoblot suggested that this was due to the liberation of active inhibitory domains from the native molecule by inter-domain proteolysis.
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PMID:Inhibitory specificity against various trypsins and stability of ovomucoid from Japanese quail egg white. 775 77

The possible antimutagenic effects of five different proteins against the mutagen 4-nitroquinoline 1-oxide (4NQO) were assessed in a mammalian cell system, using the sister chromatid exchange (SCE) test in Chinese hamster cells (V79). For this purpose the proteins casein, bovine serum albumin (BSA), soy protein, total whey protein and beta-lactoglobulin were studied, as well as pepsin-hydrolysed casein. In addition, the effect of casein on 1-methyl-1-nitroso-3-nitroguanidine (MNNG) was studied. The proteins were tested at a concentration of 1.15% (w/v). Casein was studied over a concentration range of 0 to 1.15% (w/v). A non-toxic concentration was used for the mutagens. Casein hydrolysis by pepsin took place in vitro, simulating human stomach conditions, which resulted in 84% non-casein-N and 16% remaining casein-N. Casein significantly inhibited SCE induction by 4NQO (inhibition 78%, at 1.15% casein, P < 0.05) and by MNNG (83%, at 1.15% casein, P < 0.01). BSA also significantly inhibited 4NQO-induced SCEs (94%, at 1.15% BSA; P < 0.01). However, soy protein, the whey protein fraction of milk and beta-lactoglobulin showed no inhibitory effects. Pepsin-hydrolysed casein inhibited SCE induction by 4NQO and MNNG to a similar extent as non-hydrolysed casein. It is concluded that casein, its pepsin hydrolysis products and BSA may protect mammalian cells against certain genotoxic compounds, whereas other milk proteins, such as whey protein, beta-lactoglobulin and soy protein, do not have this protective action. Although the mechanism of antimutagenicity is unknown, it seems plausible that the protein acts as a blocking agent by chemical or physical interaction with the mutagens. The accessibility of protein molecules and the presence of nucleophilic binding sites may be decisive factors in determining antimutagenic properties of proteins.
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PMID:Differential effects of milk proteins, BSA and soy protein on 4NQO- or MNNG-induced SCEs in V79 cells. 795 45

Poly(epsilon-caprolactone) (PCL) microspheres containing c. 3% bovine serum albumin (BSA) were prepared by melt encapsulation and solvent evaporation techniques. PCL, because of its low Tm, enabled the melt encapsulation of BSA at 75 degrees C thereby avoiding potentially toxic organic solvents such as dichloromethane (DCM). Unlike the solvent evaporation method, melt encapsulation led to 100% incorporation efficiency which is a key factor in the microencapsulation of water-soluble drugs. Examination of the stability of the encapsulated protein by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) demonstrated that protein integrity was unaffected by both methods of encapsulation. In vitro release of the protein into phosphate buffer examined at 37 degrees C from microspheres prepared by both techniques showed that the release rate from melt-encapsulated microspheres was somewhat slower compared to the release from solvent-evaporated spheres. Both released around 20% of the incorporated protein in 2 weeks amounting to approximately 6.5 micrograms mg-1 of microspheres. Although the diffusivity of macromolecules in PCL is rather low, it is shown that PCL microspheres are capable of delivering sufficient quantity of proteins by diffusion for prolonged periods to function as a carrier for many vaccines. Unlike poly(lactic acid) (PLA) and poly(glycolic acid) (PGA) polymers which generate extreme acid environments during their degradation, the delayed degradation characteristics of PCL do not generate an acid environment during protein release and, therefore, may be advantageous for sustained delivery of proteins and polypeptides.
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PMID:Protein release from poly(epsilon-caprolactone) microspheres prepared by melt encapsulation and solvent evaporation techniques: a comparative study. 915 Nov 93

Phytohaemagglutinin (PHA), a kidney bean lectin, is known for its binding capability to the small intestinal surface. There has been no data available, however, on the biological activity of PHA in the stomach. Recent observations indicate that PHA is able to attach to gastric mucosal and parietal cells. Therefore, we examined whether PHA affects gastric acid and pepsin secretion in rats. Rats were surgically prepared with chronic stainless steel gastric cannula and with indwelling polyethylene jugular vein catheter. During experiments, animals were slightly restrained. Gastric acid secretion was collected in 30 min periods. Acid secretion was determined by titration of the collected gastric juice with 0.02 N NaOH to pH 7.0. Pepsin activity was estimated by measuring enzymatic activity. Saline, pentagastrin and histamine were infused intravenously. PHA or bovine serum albumin (BSA) were dissolved in saline and given intragastrically through the gastric cannula. PHA significantly inhibited basal acid secretion. Inhibition of acid output reached 72% during the first collection period following PHA administration when compared, then gradually disappeared. Pentagastrin-stimulated acid secretion was repressed dose-dependently by PHA as well. Maximal inhibition was observed during the first 30 min following application of PHA. Histamine-stimulated acid secretion was inhibited by PHA in a similar manner. Pepsin secretion was not affected by PHA under either basal or stimulated conditions. These results provide evidence that PHA is a potent inhibitor of gastric acid secretion in conscious rats, but it does not affect pepsin output from the stomach.
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PMID:Phytohaemagglutinin inhibits gastric acid but not pepsin secretion in conscious rats. 1159 55

Previous studies have shown that many arachidonic acid metabolites bind to human serum albumin (HSA) and that the metabolism of these molecules is altered as a result of binding. The present study attempted to gain insights into the mechanisms by which prostaglandins bound to subdomain 2A of HSA are metabolized by catalytic processes. The breakdown of the prostaglandin 15-keto-PGE(2) to 15-keto-PGA(2) and 15-keto-PGB(2) in the presence of wild-type HSA and a number of subdomain 2A mutants was examined using a previously validated spectroscopic method which monitors absorbance at 505 nm. The species examined using this method were wild-type HSA, K195M, K199M, F211V, W214L, R218M, R218P, R218H, R222M, H242V, R257M, and bovine serum albumin. Previous studies of HSA-mediated catalysis indicated that the breakdown of HSA-bound prostaglandins results from an alkaline microenvironment in the binding site. Our results show that the catalytic breakdown of HSA-bound 15-keto-PGE(2) to 15-keto-PGB(2) results from two specific processes which are modulated by specific amino acid residues. Specifically, some amino acid residues modulate the rate of step 1, the conversion of 15-keto-PGE(2) to 15-keto-PGA(2), while other residues modulate the rate of step 2, the conversion of 15-keto-PGA(2) to 15-keto-PGB(2). Some residues modulate the rate of steps 1 and 2. In total, while our results support the involvement of certain basic amino acid residues in the catabolism of HSA-bound 15-keto-PGE(2), our data suggest that metabolism of HSA-bound prostaglandins may be a more complex and specific process than previously thought.
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PMID:Structural insights into human serum albumin-mediated prostaglandin catalysis. 1184 77

Dioscorin, the tuber storage protein of yam (Dioscorea alata cv. Tainong No. 1), was purified to homogeneity by DE-52 ion-exchange chromatography. This purified dioscorin was shown by spectrophotometric methods to inhibit angiotensin converting enzyme (ACE) in a dose-dependent manner (12.5-750 microg, respectively, 20.83-62.5% inhibitions) using N-[3-(2-furyl)acryloyl]-Phe-Gly-Gly (FAPGG) as substrates. The 50% inhibition (IC(50)) of ACE activity was 6.404 microM dioscorin (250 microg corresponding to 7.81 nmol) compared to that of 0.00781 microM (0.0095 nmol) for captopril. The commercial bovine serum albumin and casein (bovine milk) showed less ACE inhibitory activity. The use of qualitative TLC also showed dioscorin as ACE inhibitors. Dioscorin showed mixed noncompetitive inhibitions against ACE; when 31.25 microg of dioscorin (0.8 microM) was added, the apparent inhibition constant (K(i)) was 2.738 microM. Pepsin was used for dioscorin hydrolysis at 37 degrees C for different times. It was found that the ACE inhibitory activity was increased from 51.32% to about 75% during 32 h hydrolysis. The smaller peptides were increased with increasing pepsin hydrolytic times. Dioscorin and its hydrolysates might be a potential for hypertension control when people consume yam tuber.
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PMID:Both dioscorin, the tuber storage protein of yam (Dioscorea alata cv. Tainong No. 1), and its peptic hydrolysates exhibited angiotensin converting enzyme inhibitory activities. 1235 88

Comparison has been made of a simple method originated by Absolon and modified in our laboratories for assay of proteolytic activity using RISA (radioactive iodinated serum albumin-Abbott Laboratories), with the commonly used photometric methods of Anson and Kunitz. In this method, pepsin was incubated with an albumin substrate containing RISA, followed by precipitation of the undigested substrate with trichloroacetic acid and measurement of radioactive digestion products in the supernatant fluid. The I(131)-albumin bond was shown in the present studies to be altered only by the proteolytic activity, and not by the incubation procedures at various values of pH. Any free iodine present originally in the RISA was removed by a single passage through a resin column (amberlite IRA-400-C1). Pepsin was shown to be most stable in solution at a pH of 5.5. Activity of pepsin was shown to be maximal when it was incubated with albumin at a pH of 2.5. Pepsin activity was shown to be altered in the presence of various electrolytes. Pepsin activity measured by the RISA and Anson methods as a function of concentration or of time of incubation indicated that these two methods are in good agreement and are equally sensitive. Consistently smaller standard errors were obtained by the RISA method of pepsin assay than were obtained with either of the other methods.
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PMID:Comparative studies of three methods for measuring pepsin activity. 1358 10

Adsorption of proteins onto film surfaces built up layer by layer from oppositely charged polyelectrolytes is a complex phenomenon, governed by electrostatic forces, hydrogen bonds, and hydrophobic interactions. The amounts of the interacting charges, however, both in polyelectrolytes and in proteins adsorbed on such films are a function of the pH of the solution. In addition, the number and the accessibility of free charges in proteins depend on the secondary structure of the protein. The subtle interplay of all these factors determines the adsorption of the proteins onto the polyelectrolyte film surfaces. We investigated the effect of these parameters for polyelectrolyte films built up from weak "protein-like" polyelectrolytes (i.e., polypeptides), poly(L-lysine) (PLL), and poly(glutamic acid) (PGA) and for the adsorption of human serum albumin (HSA) onto these films in the pH range 3.0-10.5. It was found that the buildup of the polyelectrolyte films is not a simple function of the pure charges of the individual polyelectrolytes, as estimated from their respective pKa values. The adsorption of HSA onto (PLL/PGA)n films depended strongly on the polyelectrolyte terminating the film. For PLL-terminated polyelectrolyte films, at low pH, repulsion, as expected, is limiting the adsorption of HSA (having net positive charge below pH 4.6) since PLL is also positively charged here. At high pH values, an unexpected HSA uptake was found on the PGA-ending films, even when both PGA and HSA were negatively charged. It is suggested that the higher surface rugosity and the decrease of the alpha-helix content at basic pH values (making accessible certain charged groups of the protein for interactions with the polyelectrolyte film) could explain this behavior.
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PMID:Human serum albumin self-assembly on weak polyelectrolyte multilayer films structurally modified by pH changes. 1598 3

Electrospinning of poly(glycolic acid) (PGA)/chitin blend solutions in 1,1,1,3,3,3-hexafluoro-2-propanol was investigated to fabricate biodegradable and biomimetic nanostructured scaffolds for tissue engineering. The morphology of the electrospun PGA/chitin blend nanofibers was investigated with a field emission scanning electron microscope. The PGA/chitin blend fibers have average diameters of around 140 nm, and their diameters have a distribution in the range 50-350 nm. The miscibility of PGA/chitin blend fibers was examined by differential scanning calorimetry. The PGA and chitin were immiscible in the as-spun nanofibrous structure. An in vitro degradation study of PGA/chitin blend nanofibers was conducted in phosphate-buffered saline, pH 7.2. It was found that the hydrolytic cleavage of PGA in the blend nanofibers was accelerated by the coexistence of hydrophilic chitin. To assay the cytocompatability and cell behavior on the PGA/chitin blend nanofibrous scaffolds, cell attachment and spreading of normal human epidermal fibroblasts seeded on the scaffolds were studied. Our results indicate that the PGA/chitin blend nanofibrous matrix, particularly the one that contained 25% PGA and 75% chitin with bovine serum albumin coating, could be a good candidate for tissue engineering scaffolds, because it has an excellent cell attachment and spreading for normal human fibroblasts.
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PMID:Biomimetic nanofibrous scaffolds: preparation and characterization of PGA/chitin blend nanofibers. 1647 41

The antioxidant and antimutagenic activity of the yeast cell-wall mannan and mannan conjugates--in particular the mannan of Saccharomyces cerevisiae (M-S.c.) and conjugates of mannan S. cerevisiae with human serum albumin (M-HSA1, M-HSA2) and the microbial enzyme penicillin G acylase (M-PGA)--were evaluated in vitro in the unicellular flagellate Euglena gracilis exposed to the genotoxic agents ofloxacin and acridine orange (AO). M-S.c., M-HSA1, M-HSA2 and M-PGA show a statistically significant, concentration-dependent protective antigenotoxic activity against both compounds. M-PGA was the most efficient inhibitor of ofloxacin- and AO-induced chloroplast DNA damage, whereas M-HSA2 and M-HSA1 were less effective and M-S.c. had the lowest antigenotoxic activity. It is suggested that different mechanisms may be involved in their protective effect--antioxidant activity in the case of ofloxacin-induced DNA damage and direct adsorption of AO on mannan conjugates as possible mechanisms of protection, based on spectrophotometric measurements. The important characteristics of yeast cell-wall mannans and mannan conjugates, such as their high water solubility, their broad spectrum of biological activity, low toxicity, stability and their antimutagenic effects via different modes of action, appear to be promising features for their practical application as antioxidants and antimutagenic agents.
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PMID:Antioxidant and antimutagenic activity of mannan neoglycoconjugates: mannan-human serum albumin and mannan-penicillin G acylase. 1667 51


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