Free Acid Groups Research Articles

Correlation of the Flavor Characteristics of Swiss-Type Cheeses with Chemical Parameters

Fifteen Swiss-type cheeses were evaluated by a flavor profile method. The cheeses also were analyzed for free fatty acids in whole cheese and in the oil phase and for proteolysis, pH, carbonyls, and gross composition. The flavor notes and chemical parameters were grouped by factor analysis and correlated. Factor analysis showed that many of the free fatty acids varied together. The free fatty acid groups consisted of normal short-chain fatty acids (C4 to C10), long-chain fatty acids (C12 to C18), and branched short-chain and aromatic acids. Many of the flavor notes also were correlated. Characteristic Swiss cheese flavor notes were correlated with low pH, lipolysis, and acetic and propionic acids. Other flavors were negatively correlated with the oil to cheese distribution of many of the free fatty acids and positively correlated with pH, salt concentration, proteolysis, moisture, branched and aromatic acids, and carbonyls.

The adaptation of the small intestine after resection in response to free fatty acids

The effects of long-chain triglycerides and a mixture of free fatty acid on the adaptive response to small bowel resection were examined. Rats with a 50% small bowel resection were divided into four groups. Two received 10% of their calories intragastrically either as corn oil or as free fatty acid and the remaining calories intravenously while the two control groups were given all their calories either intravenously or orally. The results of DNA and protein determination show that free fatty acids were more effective than long-chain triglyceride in promoting adaptation (p < 0.01) in both small intestine and in the colon. Furthermore the intragastric infusion of free fatty acids was as effective as the orally fed group. Of the plasma hormones measured (gastrin, gastric inhibitory polypeptide, enteroglucagon, and insulin) gastric inhibitory polypeptide was significantly higher (p < 0.05) in the orally fed group and insulin levels in the free fatty acid group (p < 0.05) than in other groups. There was no significant difference obtained in enteroglucagon and gastrin levels for the four groups. This study shows that a small amount of free fatty acids (10% of the total calories) given by continuous gastric infusion is effective in promoting intestinal adaptation after resection.

Rat intestinal brush border membrane dipeptidyl-aminopeptidase IV: Kinetic properties and substrate specificities of the purified enzyme

The kinetic properties and substrate specificities of dipeptidyl-aminopeptidase IV (EC 3.4.14.—) detergent-solubilized and purified from the brush border membrane of rat small intestinal mucosal cells were investigated. Kinetic analysis of purified dipeptidyl-aminopeptidase IV was carried out with a variety of oligopeptides and β-napthylamide derivatives as substrates. In general, peptides with proline penultimate to the amino terminus ( XPro, X= amino acid) are more favored substrates while those with alanine ( XAla) are hydrolyzed at a slower rate. There is some activity toward substrates having leucine at both the penultimate position and amino terminus (LeuLeu). The activity of the purified enzyme toward Gly lProβ-napthylamide derivative is maximal at pH 8.4 in Tris-HCl buffer, with an activation energy of 7.98 kcal/mol. There is no requirement for metal ion. The ability of various dipeptides to inhibit Gly- l-Pro-β-napthylamide derivative hydrolysis was used to determine the binding specificity of the enzyme for the amino-terminal amino acid. These data show that a free amino acid group is necessary for enzymatic activity and increased hydrophobicity of the amino acid at the amino terminus enhances binding.

The nature of the zinc polycarboxylate cement matrix.

The matrix of a stoichiometric zinc polycarboxylate cement has been shown to be identical with zinc polycarboxylate salt, which consists principally of neutralized carboxylate, groups with a few free acid groups. When excess zinc oxide is present, as in practical cements, there are no free acid groups present. There is no evidence for the formation of a chelate. Both salt and cement matrices are amorphous. The formation of the salt appears to control time-dependent changes in the consistency of the cement pastes.

Sperm glycoproteins of the boar, bull, rabbit, and ram: II. Surface glycoproteins and free acidic groups

AbstractEjaculated spermatozoa of boars, bulls, rabbits, and rams were embedded in glycolmethacrylate and thin sections stained with phosphotungstic acid at low pH in order to observe the distribution of glycoproteins of the plasma membrane. Colloidal iron hydroxide was also used to detect the free acidic groups present on the sperm surface. Species‐specific patterns of localizations of glycoproteins and linked negative charges were observed. The distribution was sometimes homogeneous as in bull, but generally heterogeneous in the other species. The significance of the results on sperm surface components and the practical interest to know their normal distribution are discussed.

Metabolic responses of the heart in acute myocardial infarction in man

Acute myocardial infarction evokes a characteristic neurohumoral response: Catecholamine release is increased, plasma contents of free fatty acids and glucose are elevated and glucose tolerance is diminished. To what degree the myocardium participates in this stress response was evaluated by sampling coronary sinus and arterial blood in 50 patients with acute transmural infarction. Studies were initiated an average of 8 hours after the clinical onset of infarction and were continued for up to 60 hours. A total of 173 separate metabolic studies were analyzed. Forty-one percent exhibited a pattern of predominant myocardial free fatty acid uptake (mean extraction ratio 24 percent) in the presence of elevated plasma free fatty acid and glucose contents (respective means 1,181 μmol/liter and 210 mg/100 ml). Myocardial extraction ratios for glucose, lactate and pyruvate were low (respective means 1.1, 4 and 11 percent). Twenty-one percent of the studies revealed normal myocardial metabolism and 18 percent showed enhanced carbohydrate uptake, as evidenced by increased myocardial extractions of lactate and pyruvate (respective means 42 percent) and of glucose (mean 5 percent). Plasma contents of glucose and free fatty acids were lower than in the predominant free fatty acid group (respective means 156 mg/100 ml and 743 μmol/liter). The remaining 20 percent of studies showed high plasma substrate contents and low myocardial substrate uptake suggesting metabolic breakdown. The free fatty acid metabolic pattern was observed in more than 50 percent of the studies performed at the time of or close to the occurrence of important clinical complications. Propranolol, 0.1 mg/kg intravenously, shifted myocardial substrate utilization from free fatty acids toward carbohydrates. The myocardial respiratory quotient increased from an average of 0.79 to 0.88 ( P < 0.01). The study demonstrates that the metabolic patterns of the myocardium are influenced by the systemic response to stress. Beta adrenergic blockade changed substrate utilization of the myocardium, supporting the hypothesis that adrenergic activation plays an important role in these metabolic responses.

Alkylamine Salts and Amides: In Vitro Inhibition of S mutans 6715

Our studies with the salts and amides of alkylamines have shown that the undecylenate salts have significant in vitro activity against S mutans No 6715, suggesting that these agents are worthy of additional evaluation. The attempt to increase activity by combining undecylenic acid with the alkylamines was not successful; however, better attachment to tooth surfaces and/or retention during washing did occur. Our results suggest that the free amino group of alkylamines and the free acid group of undecylenic acid are required for these two classes of agents to demonstrate antibacterial activity.

The Reactions of Cellulose with Amic Acids and Anhydride/Aminonia

Formulas have been developed for the calculation of free, total, and crosslink degree of substitution in Cellulose Ester Derivatives. Free and total carboxylic acid group content from established analytical methods is required.

Recurable Durable-Press Fabrics

Cotton twill fabric was treated by a pad-dry-cure process with combinations of DMDHEU and several potycarboxytic acids. Fabrics were prepared with several ratios of catalytic rarhoxylic acid groups to DHEU residues in the modified cellulose. The wrinkle-recovery angles, durable-press appearance ratings, and strength retentions of these fabrics were equivalent to or slightly better than those imparted by the conventional DMDHEU-MgCl2 treatment. The fabrics were analyzed for nitrogen, formaldehyde, ester linkages, and free carboxytic acid groups. The ratios of formaldehyde residues to DHEU residues in the cured experimental fabrics decrease with increasing wrinkle-recovery angles of the fabric. These fabrics showed very good recurahility when prepared with selected polycartroxylic acids, e.g., citric, cyctopentanetetra cartroxylic, and tetrahydrofurantetracarboxylic acids. The rerurahility was lost by converting the free carboxyl groups in the fabric to salt forms, but was restored when the free carboxyl groups were regenerated.

Thermal-oxidative degradation of some ion-exchange resins containing phosphorus

Some phosphorus-containing cation-exchange and amphoteric ion-exchange resins have been studied by thermal analysis methods. The mechanism of decomposition of the phosphorus-containing ionizable groups has been found by a combination of the methods of thermal analysis, infrared spectroscopy, paper chromatography and elementary analysis of the residue and of the products of thermal-oxidative degradation. It was found that the amphoteric resins decompose by a mixed mechanism, comprising reactions of free phosphonic acid groups and of phosphonic acid groups in the internal-salt form.

Heparin derivatives prepared by modification of the uronic acid carboxyl groups

Heparin derivatives in which the carboxyl groups of the uronic acid are modified, were synthesized by mild procedures whereby the sulfate groups remained intact. It was found that esterification of the carboxyl group resulted in complete loss of anticoagulant activity. However, heparinyl glycine and heparinyl aminomethanesulfonic acid which contain free acidic groups had considerable effects in prolonging blood clotting. Other bulkier units which may modify the conformation of heparin, or products in which there are no free carboxyl groups had little anti-coagulant effects.

Oxygen Equilibrium of Hemoglobins Containing Unnatural Hemes: EFFECT OF MODIFICATION OF HEME CARBOXYL GROUPS AND SIDE CHAINS AT POSITIONS 2 AND 4

Stable ferro-forms of hemoglobins containing various hemes such as dimethyl proto-, dimethyl meso-, etio-, meso-, hemato-, and deuteroheme were prepared by combination of human globin with hemes, followed by reduction with dithionite and purification with carboxymethyl Sephadex column. Sedimentation coefficients of these hemoglobins were all near to 4.0 S and chemical analysis showed that 4 moles of heme were bound per mole of hemoglobin. Esterification of propionyl carboxyl groups of heme did not change the absorption spectra of hemoglobin; absorption spectra of dimethyl protohemoglobin were essentially identical with those of protohemoglobin, and absorption spectra of dimethyl mesohemoglobin with those of mesohemoglobin. Absorption spectra of etiohemoglobin, in which the propionic acid groups of mesoheme were substituted by ethyl groups, were similar to those of mesohemoglobin. Parameters of oxygen equilibrium, namely oxygen affinity, n in Hill's equation, and Bohr effect, of hemoglobin containing hemes which lack free carboxyl groups were the same as those for the corresponding hemoglobin with free propionic acid groups. Oxygen affinities of meso-, deutero-, hemato-, and protohemoglobin, in which heme side chains at positions 2 and 4 are ethyl, hydrogen, hydroxyethyl, and vinyl groups, respectively, were in the ratio of 5:2:1.3:1, corresponding to the reverse order of the negative inductive effects of the groups at positions 2 and 4. These results suggest the effect of π electron of a porphyrin ring on the oxygen binding.

A Monophenol Oxidase Activity in Extracts of Sorghum

A p-hydroxycinnamic acid oxidase activity was present in enzyme preparations from first internodes of Sorghum vulgare variety Wheatland milo when incubated in phosphate buffer at pH 7.5. This preparation had no classical polyphenolase activity but had both peroxidase and catalase activities. Since horseradish preparations catalyzed the same reaction, the oxidation probably is another example of a peroxidase-oxidase reaction. A second substrate was p-hydroxyphenylpyruvic acid. Ferulic acid was slightly active at low concentrations and inhibitory at higher ones. Diphenols such as caffeic and chlorogenic acids were inactive and inhibitory to p-hydroxycinnamic acid oxidation. A variety of monophenols such as tyrosine and cinnamic acid were inactive. An active substrate must have a free monophenolic group and para to this a C(3) side chain with a double bond and probably a free terminal acid group. A sulfhydryl reducing agent at the 5 millimolar level such as mercaptoethanol, reduced glutathione, or dithiothreitol was obligatory. Products were varied and were found in both the ethyl acetate-soluble and insoluble fractions after acidification of the incubation mixtures. With internode extracts, about 1 micromole of O(2) was consumed per micromole of p-hydroxycinnamic acid that disappeared in the presence of mercaptoethanol. Tetrahydrafolic acid plus mercaptoethanol were required for a second step oxidation or a parallel reaction; about 2 micromoles of O(2) were consumed per micromole of p-hydroxycinnamic acid that disappeared. Potassium cyanide, diethyldithiocarbamate, ascorbic acid, and ethylenediaminetetraacetate were inhibitory. A similar mercaptoethanol-dependent monophenol oxidase was present in preparations from green shoots that also contained a classical polyphenolase activity. The activity was present in both soluble and particulate (500 to 100,000 gravity) fractions of internodes. Preliminary studies were made of enzyme complexes in the particulate fractions capable of converting phenylalanine and tyrosine to the level of ferulic acid when the above p-hydroxycinnamic acid oxidase was blocked with ascorbic acid. The ratelimiting step was the hydroxylation of p-hydroxycinnamic acid.

The structure and polysaccharide cytochemistry of the jelly envelopes of the egg of the frog, Rana pipiens

AbstractThe structure and polysaccharide constitution of the jelly capsule of the egg of Rana pipiens is described. Microscopic examination of the jelly capsule revealed the presence of five discrete jelly layers that differed clearly in their response to selected cytochemical tests. These layers were classified as M1‐through M5 from the inner to the outermost layer. A sixth layer occasionally could be observed between M3 and M4.All layers contain neutral mucopolysaccharides. In addition layers M1 and M3 contain sulphated mucopolysaccharides, M2 and M4 contain non‐sulphated acid mucopolysaccharides, and layer M5 contains both sulphated and non‐sulphated acid mucopolysaccharides. M2 may also contain a small quantity of sulphated mucopolysaccharides. The layer that occasionally appears between M3 and M4 is probably an area in which free acidic groups are in higher concentration than in adjacent areas rather than being a discrete jelly layer. Neither hyaluronic acid nor sialic acid was localized by the methods employed.The possible significance of some of these constituents is discussed.

The occurrence of neutral and acidic mucins in the reproductive tract of the laying hen.

The tissues of the domestic hen's reproductive tract have been shown to contain both acidic and neutral mucins. The presence of an egg in the isthmus was always accompanied with an increase in the concentration in the isthmus secretory epithelium of PAS-positive mucins without free acidic groups. Staining of uterine tissue for strongly acidic groups with basic dyes was greater when an egg had been present in the shell gland at the time of death and the same was true for tissues of the upper oviduct. The results are discussed with special reference to the periodic secretion of organic mammillary core and egg shell mucins.

Structural changes in mitochondria induced by uncoupling reagents. The response to proteolytic enzymes.

Interaction of uncoupling reagents with bovine serum albumin markedly inhibited its hydrolysis by proteolytic enzymes. The inhibition presumably is due to conformational transitions in the protein substrate induced by the binding of the ligand-uncoupling reagents. The proteolysis of casein, a protein that does not bind these reagents, was not affected, indicating that the proteinases themselves were not inactivated. In contrast, interaction of uncoupling reagents with freshly isolated rat liver mitochondria enhanced their susceptibility to proteolytic enzymes. This was shown by an increase in the release of ninhydrin-reacting material, by an increase in free acid groups and by a decrease in the turbidity of the mitochondrial suspensions. These effects, although opposite in direction to those obtained with albumin, are also presumed to indicate structural changes in the mitochondrial proteins and a disorganization of the protein-phospholipid complex. It is suggested that such structural alterations are expressed functionally as the uncoupling of oxidative phosphorylation.

EFFECT OF PHOSPHOMOLYBDIC ACID ON THE BINDING OF SUDAN BLACK B.

Paraffin sections of tissues fixed in absolute alcohol or Carnoy's fluid were mordanted in a 1% aqueous solution of phosphomolybdic acid, stained in saturated solutions of Sudan black B, acetylated Sudan black, various solvent and basic dyes in 70% ethyl alcohol for 5 min at room temperature, dehydrated in alcohol and covered in Permount. Sudan black B and other dyes with basic groups stained basement membranes, reticulum and collagen fibers intensely. Acetylated Sudan black, Sudan IV and oil red 0 did not color any tissue structures. Control sections, without pretreatment, did not bind Sudan black B. These findings indicate interaction between basic groups of the dye and free acid groups of phosphomolybdic acid.

Anionic polymerization of epichlorhydrin

AbstractThe anionic polymerization of epichlorhydrin with potassium hydroxide was studied at 110–120°C. in bulk and in solution. Large molar equivalent ratios of catalyst were needed for polymerization and even when using 150 mole‐% catalyst, the conversion was only about 50%. The polymers obtained were crosslinked and had a low chlorine content. Crosslinking may be due to attack of a propagating chain end on the partially positive carbon attached to the chlorine atom in a polymer, or on a terminal epoxide formed by an intramolecular elimination of chlorine. The water of hydration in the catalyst influenced the polymerization in that it was released on consumption of catalyst causing termination of the polymerization, relatively low conversion, and low chlorine content of the polymers. The polymers had infrared absorptions for both carbonyl and carbon double bonds and gave dinitrophenyl hydrazones that indicate the presence of aldehydes or ketones. Preliminary experiments showed that the crosslinked polyepichlorhydrins obtained can be converted to exchange resins by utilizing either the hydroxyl or the chlorine functions of the polymer. Thus sulfonation and phosphorylation of the polyhydroxy polymer obtained by alkaline hydrolysis of residual chlorine in the polyepichlorhydrin gave inorganic esters that had free acid groups and served as reversible cation‐exchange resins. Amination of the polymers with sodamide gave an anion‐exchange resin, while replacement of the chlorine with cysteine gave a resin that can be used as a chelating agent for heavy metals.

Properties of the fatty acid esters of amylose

AbstractTo help establish the suitability of esters of amylose and fatty acids as dip‐coating materials, esters of the evennumbered, saturated fatty acids, acetic through stearic, and of oleic and cottonseed oil fatty acids were prepared, and their properties were determined.The various esters generally were prepared by the interaction of acid chlorides with the amylose suspended in a suitable mixture of solvents. Analyses for content of free fatty acid groups indicated that high proportions of the hydroxyl groups were esterified. Intrinsic viscosity decreased as the chain length of the acyl group increased, a reflection of the changing nature of the products rather than a decrease in the degree of polymerization of the amylose.As the chain length of the saturated fatty acid group increased the softening point at first decreased and then increased, the minimum being obtained with the myristate. The stearate softened at 56.2ŶC. The stearate had a hardness index of 139, which was about equal to the index of 140 for completely hydrogenated cottonseed oil. Densities were greater than those of the corresponding triglycerides and decreased as the chain length of the fatty acid group increased. Permeability to water vapor also decreased as the chain length increased, the index being 620ȕ10蜢12 for the acetate and 15ȕ10蜢12 for the stearate. The acetate possessed the highest tensile strength, about 4.40 kg./sq. mm., while the palmitate had a tensile strength of about 0.49 kg./sq. mm. Elongation at the break point varied widely, being 632% for the caprate and 0.95% for the stearate.

The Rates of Desorption of Level‐dyeing Acid Dyes from Wool

A study of the initial rates of desorption of level‐dyeing acid dyes from wool into sodium borate (borax) solution has indicated a linear relationship between the dye removed, expressed as a percentage of the total dye initially present, and the square root of the time. Activation energies of diffusion during desorption from wool have been determined for several dyes.The effects of method of application of dye, nature of dye, and nature of substrate on rates of desorption of acid dyes from wool have been determined. It is shown that the rate of desorption is controlled by the relative magnitudes of the forces of repulsion between the charged fibre and the dye anion and the forces of attraction, such as van der Waals, hydrogen bonds, etc., between fibre and dye. Any fibre modifieation which results in an increase in the number of free acidic groups, such as dyeing at low pH values, acid chlorination. or peroxide bleaching, increases the rate of removal of dye by alkaline solution.