High Molecular Weight Acid Research Articles

Development of an anion-exchange membrane with increased permeability for organic acids of high molecular weight

Ion-exchange membranes are mainly used today in electrodialysis for desalination of sea and brackish water. The membranes have been optimized for this application in terms of their ion selectivity and their mechanical, chemical and electrical properties. They are, however, unsatisfactory for the separation of organic components such as amino acids because of their poor permeability for larger anions which is required in certain applications in the food and pharmaceutical industry. In this paper the development of an anion-exchange membrane with high permeability for large organic anions and satisfactory mechanical, chemical and electrical properties is described. The membrane is prepared by changing the degree of cross-linking of the basic ion-exchange polymer.

Low temperature free radical polymerization initiated by the system t-butyl hydroperoxide-acetone-sulphonic acid of low or high molecular weight

We have examined the initiating system consisting of t-butyl hydroperoxide, acetone and organic sulphonic derivatives for the methyl methacrylate (MMA) polymerization at 313 K. The rate of reaction depends on the concentration of an initiator component (low molecular weight or polymeric sulphonic compounds) with the exponent 0.5. The temperature coefficient for the initiation over the range 292.5–323 K is only ca 50% that for spontaneous thermal decomposition of peroxides. When the sulphonic groups are attached to a polymer chain, the activity of the initiating system depends inversely on the frequency of sulphonic groups along the chain. The activity of this initiator may be very high. MMA bulk polymerization (at concentrations of 0.2 M acetone and 0.012 M t-butyl hydroperoxide, with acid groups bound to MMA-co-styrene copolymer being one for 45 chain units on average) has a rate of 41% hr −1, approximately twice that when sulphuric acid is used.

Edaphic mobility of complete humic acid and fractions of high and medium molecular weight

Soil mobility of a complete humic acid and high and medium molecular weight fractions was determined by a soil TLC method. High and medium molecular weight fractions were obtained by ultrafiltration and then labeled with radioiodine. Infrared, visible- and UV spectra, as well as isotachophoretic studies, showed marked differences among the three humic fractions. The results obtained made evident the presence of soil mobile humic fractions of medium molecular weight. Alkalinization increased the soil mobility of humic acid.

Studies on the Enzymes of Sarcocystis suicanis: Purification and Characterization of an Acid Phosphatase

Percoll density gradient centrifugation was used for isolating large quantities of bradyzoites of Sarcocystis suicanis, which were used for enzymatic analysis. Crude extracts of bradyzoites contained activities suggestive of several acid hydrolases. Levels of acid and alkaline phosphatase were higher than those of beta-N-acetylhexosaminidase and beta-galactosidase. Acid phosphatase was purified 156-fold with an overall recovery of 54% using DEAE-Sepharose 4B and Sephadex G-200 chromatography. The partially purified enzyme was not a glycoprotein and had a molecular weight of approximately 170,000. The enzyme was markedly inhibited by Cu++, Hg++, and iodoacetamide, suggesting the presence of a sulfhydryl group. Sodium tartrate caused strong inhibition of the enzyme. The acid phosphatase of S. suicanis appears to be a unique enzyme that cannot be classified under high or low molecular weight acid phosphatases of widely diverse origin.

Characterization of Multiple Acid Phosphatases in Salt-Stressed Spinach Leaves

Incremental salt stress brought about a clear enhancement of the activity of acid phosphatases in hydroponically grown spinach (Spinacia oleracea L.) leaves. Sephacryl S-200 chromatography of the enzyme fraction revealed multiple forms of acid phosphatases of high (300 000), intermediate (100 000), and low (35 000) molecular weight in control and salt-stressed spinach leaves. A similar zymogram of acid phosphatases, showing at least six bands in polyacrylamide disc gel electrophoresis, was observed for control and stressed leaves. However, promotive effects of incremental salt stress on the activity of acid phosphatases were more pronounced in high molecular weight acid phosphatases. Substrate specificity and differential effects of some ions on the multiple acid phosphatases were also examined for control and salt-stressed leaves.

Subcellular localization of high- and low-molecular weight acid phosphatases from chicken liver

1. 1. The subcellular localization of high and low molecular weight acid phosphatases in chicken liver was studied. 2. 2. The high molecular weight acid phosphatase is mainly associated with the particulate fraction, particularly with the mitochondrial-lysosomal fraction, whereas the low molecular weight form seems to be a soluble cytoplasmic enzyme. 3. 3. Biochemical properties including optimal pH, molecular weight determination and the effect of some modifier substance indicate that mitochondria-lysosomes and microsomes contain the same high molecular weight acid phosphatase form.

A 155K acid carboxypeptidase O from Aspergillus oryzae.

When Aspergillus ory, zae IAM 2640 was grown in liquid medium, a high molecular weight acid CPase was produced exclusively in the medium. The enzyme was purified and characterized. The purified enzyme was homogeneous by PAGE at pH 9.4, by isoelectric focusing, and by FPLC, and its molecular weight was 155K by gel filtration. When the 155K enzyme was electrophoresed in SDS-polyacrylamide gel, a single band with a molecular weight of 73K was obtained. The enzyme was inhibited by TPCK and PMSF but not IAA or PCMB. The Km and kcat values of the enzyme for Z-Glu-Tyr, angiotensin, and bradykinin at pH 3.7 and 30°C were 0.48mM, 86 sec-1, 0.1 mM, 0.34sec-1, and 0.06mM, 14.7 sec-1, respectively. The enzyme hydrolyzed proangiotensin and bradykinin sequentially at pH 3.7 from their C-terminus. The enzyme shared an antigen with low molecular weight A. oryzae acid CPase O-1.

Isolation and partial characterization of high and low molecular weight acid phosphatases from chicken liver

1. 1. Two acid phosphatase forms were isolated from chicken liver by gel filtration on Sephadex G-100. 2. 2. These enzymes, termed I and II. have similar K m - and V max -values. but differ in molecular weight. optimum pH, sensitivity to various inhibitors and substrate specificity. 3. 3. The results were compared with the numerous literature reports of mammalian acid phosphatases.

An integrated chemical and micromorphological investigation of humic substances in three podzolized soils of the Netherlands.

The humic substances in a 'Holt' leptic podzol, a 'Haar' humic podzol and a 'Veld' gleyic podzol from the Netherlands were analysed chemically and micromorphologically. The absorption spectra of Na-humates in visible light and infrared spectra were determined for the humic acids. The translocation and distribution of the principal humus compounds occurred by mechanical illuviation in the 'Holt' podzol, and by translocation in solution in the 'Haar' podzol and the 'Veld' podzol. The micromorphological images were closely correlated with the chemical composition of the humic substances. Illuviation cutans occurring in the B horizons of the 'Haar' podzol and the 'Veld' podzol appeared to consist mainly of fulvic acids. The dark humus micro-aggregates characteristic of the 'Haar' podzol and the Ap horizon of the 'Veld' podzol were composed mainly of bitumens, humins and humic acids of high molecular weight, while the brown micro-aggregates of the 'Holt' podzol and the lower horizons of the 'Veld' podzol consisted mainly of fulvic acids and humic acids of low molecular weight. The stability of micro-aggregates was correlated with their composition. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Precipitation of nucleotides by calcium phosphate

Earlier it has been shown that nucleic acids of high molecular weight can be introduced into cells by coprecipitation with calcium phosphate. We have studied the requirements for calcium phosphate coprecipitation of shorter nucleotides. The degree of coprecipitation of dodecanucleotides lacking terminal phosphate varied between 25 and 72%. Tetramers with a 5′-monophosphate were coprecipitated to 29–87% by calcium phosphate. A high content of guanosine residues and an increased number of terminal phosphate groups increased the degree of coprecipitation of nucleotides. The trinucleotide pppA2′p5′A2′p5′A was effectively precipitated by calcium phosphate but the monophosphate and the core structure were not.

Copolyimides new polybenzoxazinone‐imides

AbstractNew polybenzoxazinone‐imides have been synthesized by cyclopolycondensation reaction of 4,4′‐diaminodiphenylmethane‐3,3′‐dicarboxylic acid with diacid chlorides containing preformed imide rings. The low temperature solution polycondensation technique, used in these experiments, afforded poly(amic acids) of high molecular weight in the first step, which subsequently underwent thermal cyclodehydration at 200–300°C to give polybenzoxazinone‐imides in the second step. The obtained polymers have been characterized by IR absorption, elemental and thermogravimetric analyses. From 10% polymer solution flexible and transparent films have been cast with good mechanical and insulating properties.

Isolation of deoxyribonucleic acid from Mycobacterium avium by rapid nitrogen decompression.

Deoxyribonucleic acid (DNA) of high molecular weight could be isolated from cells of Mycobacterium avium if the cells were exposed to nitrogen gas at 1,500 lb/in2 for 30 min and then brought to atmospheric pressure by rapid decompression. DNA isolated from the cells had a molecular weight of 4.8 x 10(6) to 17.4 x 10(6). DNA was also released into the fluid in which the cells were suspended during nitrogen decompression. One-half of this DNA, representing 3% of the total DNA phosphorus in the cells had a uniform molecular weight of 4.2 x 10(6). This DNA was linear in conformation, and removal of associated carbohydrates did not change its sedimentation rate. The biological function or significance of the 4-megadalton DNA was not determined.

Purification and partial characterization of two acid phosphatases from rat bone.

Acid phosphatase activity in homogenized tibiae and femora of suckling rats was extracted with 0.3M KCl and 0.1% Triton X-100. A high-speed supernatant was treated with protamine sulfate, dialyzed, and chromatographed on CM-52 cellulose. All of the acid phosphatase activity was eluted with a sodium acetate buffer and combined ionic strength-pH gradient into two peaks (E1 and E2). Both enzyme peaks were further purified with Sephadex G-200, which resulted in 700- and 1000-fold purification for E2 and E1, respectively. A total of 220 units (mumoles substrate/min) of E2 with a specific activity of 160 units/mg protein has been obtained in one run by this procedure. E1 has a high molecular weight (greater than 100,000) and shows preference for monophosphate ester substrates, is markedly inhibited by tartrate, and has a pH optimum near 5. E2 has a lower molecular weight (greater than 40,000) and shows negligible activity with monophosphate esters [except with p-nitrophenyl phosphate (p-NPP)], but high activity with ADP and ATP. E2 is unaffected by tartrate and shows a pH optimum near 6. Both enzymes are competitively inhibited by inorganic phosphate, and E2, but not E1, is markedly inhibited by p-chloromercuribenzoate. With p-NPP as substrate, E1 and E2 have distinctly different values for Km. E1 appears similar to the high molecular weight acid phosphatases of soft tissues. However, E2 appears to differ from the low molecular weight phosphatases in soft tissues with regard to substrate specificity.

マウス腹水肉腫細胞核からの高分子量酸可溶性蛋白質の精製とその性質

マウス腹水肉腫細胞核からの高分子量酸可溶性蛋白質の精製とその性質

The persistence length of hyaluronic acid: An estimate from small-angle X-ray scattering and intrinsic viscosity

Measurement of small-angle X-ray scattering from a sample of hyaluronic acid of high molecular weight in 0.05 m HNO 3 gave persistence length plots which agreed in form with theory and led to apparent persistence lengths of from 4 to 6 nm. Similar measurements in 0.2 m NaCl gave plots which deviated somewhat in form from theoretical expectation, but which could be interpreted to give a persistence length of 4 nm in this solvent. Data for intrinsic viscosity [η] as a function of molecular weight were in reasonable agreement with the Yamakawa-Fujii treatment of [η] for the worm-like chain model for a persistence length of about 4 nm in both 0.5 m NaCl and 0.1 m HCl, perhaps slightly higher in the latter. The values of persistence length estimated from [η] depend somewhat on the choice of chain parameters and the method of correction of experimental data to unperturbed solvent conditions. Experimental data for the sedimentation coefficient, while less definitive, were consistent within experimental uncertainty with the same parameters of the worm-like chain model. These calculated results are in substantial agreement with the values derived from small-angle X-ray scattering. A fraction of hyaluronic acid of low molecular weight in 0.05 m HNO 3 gave an estimated molecular weight of 2.7 × 10 4 and a radius of gyration of 8 nm, in reasonable agreement with expected values based on the worm-like chain model for a persistence length of about 4 nm.

Correlation of Polynuclear Aromatic Hydrocarbon Formation Between Pyrolysis and Smoking

AbstractTobacco, its petroleum ether (PE) extract, and the residual extracted tobacco (marc) were pyrolyzed at 650-750°C, 650-850°C, and 700°C, respectively. Analyses of the polynuclear aromatic hydrocarbons (PAH) produced showed that the pyrolysis of the tobacco and the PE extract at 700°C produced PAH profiles comparable to those found in cigarette smoke condensate (CSC). The data indicated that most of the alkyl PAH and the major PAH in cigarette smoke are derived from the PE extractables of tobacco. The constituents of the marc were the major precursors for phenols, oxygenated PAH, and Iow molecular weight acids; and those of PE extract were the major producers of high molecular weight acids.

Subcellular distribution of low- and high-molecularweight acid phosphatases

Acid phosphatases (orthophosphoric-monoester phosphohydrolases (acid optimum), EC 3.1.3.2) of low and high molecular weight were separated by Sephadex G-75 filtration from extracts of rat brain, liver and kidney. The proportion of each phosphatase in the extract depends critically on the method employed for homogenate preparation, and no interconversion between high and low molecular weight forms was detected. In extracts obtained from subcellular organelles only high-molecular-weight acid phosphatase was detected, which is of lysosomal origin. Low-molecularweight acid phosphatase is restricted to the cell sap. Low- and high-molecular-weight acid phosphatases were characterized by their elution volumes, specific inhibition and activity with two substrates. It is suggested that the distribution pattern found in rat tissues could be common to all eukaryotic cells.

Influence of ratio of low- to high-molecular-weight acids on the thermal-oxidative stability of complex calcium greases

1. The oxidizability of complex Ca greases varies as an extremal-type function of the ratio of low to high molecular-weight acids. The most stable greases are those with a 1.5∶1 ratio of acetic acid to stearic acid or a 1∶1 ratio of acetic acid to synthetic fatty acid fraction. 2. Greases prepared with the synthetic fatty acids are more resistant to oxidation than are greases prepared with stearic acid. 3. The volatility of complex Ca greases decreases with increasing relative amount of acetic acid.

Interspersion of repetitive and single-copy sequences in nuclear ribonucleic acid of high molecular weight.

Nuclear RNA of high molecular weight, approximately 15 to 30 x 10(3) nucleotides long, isolated from rat ascites cells, has been shown previously to contain both middle repetitive and single-copy sequences. However, it was not known whether these sequences were located on separate molecules or whether they were interspersed within the same molecule. The present communication distinguishes between these possibilities and shows that a large proportion of nuclear RNA of high molecular weight consists of interspersed middle repetitive and single-copy sequences.

The release of intracellular dipeptidase from starter streptococci during Cheddar cheese ripening

SummaryIntracellular dipeptidase ofStreptococcus cremorisNCDO 924 has been investigated as a marker enzyme for detecting the release of starter enzymes into Cheddar cheese during maturation. Dipeptidases were produced extra- and intracellularly byStr. cremorisin broth cultures, but the intracellular enzyme was distinguishable by its relatively high activity against L-alanylglycine at low temperatures. The presence of dipeptidase activity of intracellular origin was demonstrated in extracts of Cheddar cheese freed from whole starter cells, opaque material of high molecular weight and free amino acids by a combination of centrifugation and gel filtration on Sephadex G200. The enzyme was not detected in cheeses made without starter (δ-gluconic acid lactone cheeses). In fresh curd with a high viable count of starter the dipeptidase activity was low and mostly extracellular. As the count declined the proportion of intracellular enzyme activity increased, reaching a maximum when 90% of the starter cells had died. The total dipeptidase subsequently decreased until the level remained 30% higher than that of the original curd, and changed little on further ripening up to 120 d. There remained a significant proportion of extracellular dipeptidase activity throughout the maturation period studied.