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At least 19 recordsLinked to original sources
PubMed1980

The molecular weight and molecular weight distribution of hydroxypropyl methylcellulose used in the film coating of tablets.

The molecular weight and molecular weight distributions of nine grades of hydroxypropyl methylcellulose used in the film coating of tablets have been measured using gel permeation chromatography. With the exception of Pharmacoat 603, there is a high molecular (greater than 5 x 10(5)) component present in all grades ranging from relatively small amounts in grades with low nominal viscosity to relatively large amounts in the 50 mPas grade. The peak molecular weight taken from the distribution curve--an indication of the molecular weight of the main component--could be calculated from the nominal viscosity using the equation. Peak molecular weight = 23.54 x 10(3) (viscosity)0.45. The relationship could also be expressed in the standard form [eta]=KM alpha where M is the peak molecular weight [eta] is the intrinsic viscosity and K and alpha are constants (in this case 9.94 x 10-4 and 1.096 respectively). The wide molecular weight distribution of these samples and the presence of quite high proportions of very low molecular weight (less than 5 x 10(3)) components especially in samples with nominal viscosity designations of less than 15 mPas appears to affect their mechanical properties.

Chromatography, Gel↗
PubMed2006

Immunostimulatory polysaccharides from Chlorella pyrenoidosa. A new galactofuranan. measurement of molecular weight and molecular weight dispersion by DOSY NMR.

Fractionation of the hot water extract of Chlorella pyrenoidosa was performed using a combination of ethanol precipitation, size exclusion chromatography, and anion exchange chromatography. One fraction contained a new polysaccharide, and this compound was shown to be a 1-->2-linked beta-d-galactofuranan from its 1D and 2D (1)H and (13)C NMR spectra, with a molecular weight of 15 kDa from DOSY NMR measurements. A number of other fractions were shown to have the same repeating unit as the previously identified arabinogalactan. However, arabinogalactans from different fractions were shown by DOSY NMR to have different molecular weights, which ranged from 27 to 1020 kDa. Agreement with molecular weights measured for some of these fractions by SEC-MALS was very good, further confirming the relationship established by Viel et al. between molecular weights of neutral polysaccharides and self-diffusion coefficients. The smaller molecular weight polysaccharides, the galactofuranan and the 27 and 50 kDa arabinogalactans, were shown to be close to monodisperse by analysis of the distributions of the self-diffusion coefficients for the polymers. The larger arabinogalactans had considerable variation in their molecular weights (188 +/- 109 kDa and 1020 +/- 370 kDa). Only the two larger arabinogalactans showed immunostimulatory activity.

Adjuvants, Immunologic↗
PubMed1981

Isolation of size homogeneous preparations of high molecular weight and low molecular weight fibrinogens.

Molecular sizes of fibrinogen (F) similar to FI, higher molecular weight form, and FII, lower molecular weight form, have been found by Lipinska and colleagues. A procedure has been developed to isolate for the first time each of the FI and FII forms of fibrinogen which are free of each other and of high molecular weight fibrin-fibrinogen complexes. This process involved removing the complexes by A-5 m chromatography. This chromatography also reduced a protein contaminant (X) and removed plasminogen. (NH4)2SO4 subfractionation at pH 5.9 was then done. A subfraction (16-18%) containing 90% FI and another (22-25% or 25-28%) containing 96% FII were obtained. Reprecipitation of the first 16-18% subfraction yielded a subfraction containing 97% FI. sodium dodecyl sulfate (SDS) - polyacrylamide gel electrophoresis of FII revealed that it contains one intact a alpha chain per (b beta, gamma)2. Clot opacity studies on FII suggested that the carboxyl terminal portion of the alpha chain of fibrin plays an important role in the lateral associations in fibrin polymerization. Also, the pattern of (NH4)2SO4 precipitation of the endogenous fibrin-fibrinogen complexes was studied. This revealed that the complexes precipitated mostly in the least soluble subfractions, but small amounts could be found in all subfractions. Examination of the complexes by SDS-polyacrylamide gel electrophoresis showed that most of the complexes could be dissociated to FI and FII. However, there were complexes which remained and these were found to be covalently cross-linked forms probably produced by factor XIII.

Ammonium Sulfate↗
PubMed1994

Molecular weight of low molecular weight heparins by 13C nuclear magnetic resonance spectroscopy.

Heparin and low molecular weight heparins are polydisperse polysaccharides with a degree of polymerization ranging from 4 to approximately 40. The determination of their average molecular weights has traditionally relied on size exclusion chromatography involving the use of oligosaccharides of known size and molecular weight as standards. 13C NMR spectroscopy is applied for the first time to obtain the molecular weights of low molecular weight heparins. The signal intensities of the reducing end and internal anomeric carbons, having distinctive chemical shifts in the 13C NMR spectrum, are measured to determine the molecular weight. Compared to techniques utilizing broad band decoupling or selective decoupling of anomeric protons, distortionless enhancement polarization transfer pulse sequence gave better quantitation of signal intensities of anomeric carbons. Molecular weight was calculated from the calibrated ratio of signal intensities of the anomeric carbons of reducing end groups and internal residues, and the disaccharide compositional analysis. The calibrated signal intensity ratio is determined using the T1 relaxation rates of anomeric carbons of model oligosaccharides. The disaccharide composition of low molecular weight-heparins is obtained using capillary electrophoresis. Signal averaging over 40,000-90,000 transients, requiring a total of 12-18 h on a 360-MHz NMR spectrometer was adequate to measure molecular weights in the range of 3000-7000. The measured molecular weights of twelve low molecular weight heparins, analyzed by this 13C NMR spectroscopic technique, correlated well with the number average molecular weights obtained using high performance-gel permeation chromatography and gradient polyacrylamide gel electrophoresis. In addition to establishing the number average molecular weight, the 13C NMR spectra helped distinguish the structural properties of different commercially prepared low molecular weight heparins.

Carbohydrate Sequence↗
PubMedDate not supplied

[Comparison of biological activity of high molecular weight and low molecular weight forms of immunoreactive prolactin from human serum in cultured lymphoma NB2 cells].

In experiments with NB2 rat lymphoma cells culture sensitive to lactogenic hormones the mitogenic activity of high molecular weight (> OOK) immunoreactive prolactin, found in substantial quantities in serum of certain hyperprolactinemic women, as compared to the activity of serum low molecular weight (23K) form, was studied. It was established that the ratio of immunoreactive to biologically active prolactin content in serums in cases of low molecular weight form predominance is close to 1,0 whereas in case of predominant content of high molecular weight form it is substantially higher (1.5-2.3), apparently because of low biological activity of high molecular weight form. Direct comparison of mitogenic effects of equivalent quantities of serum immunoreactive prolactin forms with high and low molecular weight, separated by gel-filtration, confirmed low biological activity of high molecular weight form. Monoclonal antibodies to prolactin completely suppressed mitogenic activity of low molecular weight form and only partially--high molecular weight one. The data obtained indicate that high and low molecular weight forms of human serum immunoreactive prolactin differ in their biochemical and functional characteristics. Therefore their ratio in the circulating blood can substantially affect the clinical manifestations of hyperprolactinemia.

Animals↗
PubMed1998

Inhibition of allergic airway responses by inhaled low-molecular-weight heparins: molecular-weight dependence.

Inhaled heparin prevents antigen-induced bronchoconstriction and inhibits anti-immunoglobulin E-mediated mast cell degranulation. We hypothesized that the antiallergic action of heparin may be molecular weight dependent. Therefore, we studied the effects of three different low-molecular-weight fractions of heparin [medium-, low-, and ultralow-molecular-weight heparin (MMWH, LMWH, ULMWH, respectively)] on the antigen-induced acute bronchoconstrictor response (ABR) and airway hyperresponsiveness (AHR) in allergic sheep. Specific lung resistance was measured in 22 sheep before and after airway challenge with Ascaris suum antigen, without and after pretreatment with inhaled fractionated heparins at doses of 0.31-5.0 mg/kg. Airway responsiveness was estimated before and 2 h postantigen as the cumulative provocating dose of carbachol in breath units that increased specific lung resistance by 400%. All fractionated heparins caused a dose-dependent inhibition of ABR and AHR. ULMWH was the most effective fraction, with the inhibitory dose causing 50% protection (ID50) against ABR of 0.5 mg/kg, whereas ID50 values of LMWH and MMWH were 1.25 and 1.8 mg/kg, respectively. ULMWH was also the most effective fraction in attenuating AHR; the ID50 values for ULMWH, LMWH, and MMWH were 0.5, 2.5, and 4.7 mg/kg, respectively. These data suggest that 1) fractionated low-molecular-weight heparins attenuate antigen-induced ABR and AHR; 2) there is an inverse relationship between the antiallergic activity of heparin fractions and molecular weight; and 3) ULMWH is the most effective fraction preventing allergic bronchoconstriction and airway hyperresponsiveness.

Aerosols↗
PubMed1976

Determination of molecular weight and molecular structure of rat-liver pyruvate carboxylase.

The molecular weight of pyruvate carboxylase isolated from pigeon and rat liver mitochondria was examined using analytical ultracentrifugation and electron microscopy. The enzyme molecule appeared as a tetramer with the four subunits arranged at the corners of a square. Sedimentation studies in the analytical ultracentrifuge, extrapolated to infinite dilution, showed the tetramer to have a molecular weight Mc=0r of 280 000 and an So20,w of 12.7 S. The tetramer could be dissociated into trimers and dimers of lower specific enzymic activity by storage at 4 degrees C or incubation at -- 20 degrees C at low protein concentrations. The isolated trimers and dimers had a molecular weight Mc=0r of 210 000 and 140 000, respectively, and an So20,w of 10.85 S and 7.55 S, respectively. Incubation with 2 M urea at 20 degrees C yielded enzymically inactive subunits (Mc=0r = 70 000; So20,w = 4.95 S). The molecular weights (for pyruvate carboxylase and its subunits), as calculated from the subunit diameter observed in the electron microscope, were consistent with the values obtained from sedimentation studies.

Animals↗
PubMed1985

Cloning and sequence analysis of cDNAs for human high molecular weight and low molecular weight prekininogens. Primary structures of two human prekininogens.

cDNA sequences for both human high molecular weight (HMW) and low molecular weight (LMW) prekininogens have been isolated by molecular cloning and determined by sequence analysis. The sequence determination together with the S1 nuclease mapping and RNA blot-hybridization analyses indicate that human HMW and LMW prekininogen mRNAs share an identical sequence throughout the 5'-untranslated region and the protein-coding region up to the sequence encoding the 12 amino acids distal to the bradykinin sequence, and the two mRNAs then completely diverge from each other. The signal peptide, the heavy chain (H chain), and the bradykinin moiety, which are common between the two prekininogens, consist of 18, 362, and 9 amino acids, respectively, while the light chains (L chains) of the HMW and LMW prekininogens are composed of 255 and 38 amino acids, respectively. All 17 cysteine residues present in the human and bovine H chains are located at exactly equivalent positions, indicating that the human H chain, like the bovine counterpart, can form 8 loop structures, each connected by two adjacent cysteine residues. The L chains of human and bovine kininogens differ in the protein lengths as well as in some amino acids crucial for the processing of the kininogens by kallikrein. Based upon this finding, we have discussed the molecular basis for the different modes of processing of human and bovine HMW kininogens and for the different kinetics of contact activation reactions exhibited by the two HMW kininogens.

Amino Acid Sequence↗
PubMed2000

Determination of the absolute molecular weight averages and molecular weight distributions of alginates used as ice cream stabilizers by using multiangle laser light scattering measurements.

High-performance size exclusion chromatography with multiangle laser light scattering detection (HPSEC-MALLS) was used for characterizing complete molecular weight distributions for a range of commercial alginates used as ice cream stabilizers. For the samples investigated, molecular weight averages were found to vary between 115 000 and 321 700 g/mol and polydispersity indexes varied from 1. 53 to 3.25. These samples displayed a high content of low molecular weights. Thus, the weight percentage of material below 100 000 g/mol ranged between 6.9 and 54.4%.

Alginates↗
PubMedDate not supplied

A single gene for bovine high molecular weight and low molecular weight kininogens.

A potent vasoactive peptide, bradykinin, is liberated from two distinct kininogens designated low molecular weight (LMW) and high molecular weight (HMW) kininogens. We have recently cloned and sequenced cDNAs for bovine LMW prekininogens and indicated that LMW prekininogens are encoded by two very similar but distinct mRNAs. This study concerns the structural basis for the relationship between HMW and LMW prekininogen mRNAs by examination of cDNA clones for bovine HMW prekininogens and a genomic clone. Two types of cDNAs for HMW prekininogens have been identified. The deduced sequences of these two mRNAs are identical with those of two LMW prekininogen mRNAs up to the regions preceding the sequences specifying the divergent C-terminal regions of HMW and LMW kininogens, with one-to-one correspondence. In genomic DNA, the sequence precisely corresponding to the divergent 3'-terminal region of LMW prekininogen mRNA is located after 87 nucleotides downstream from the sequence specifying the 3'-untranslated region of HMW prekininogen mRNA. Based on these findings, we conclude that HMW and LMW prekininogen mRNAs are transcribed from the same gene.

Amino Acid Sequence↗
PubMed1987

Mapping of functional domains of human high molecular weight and low molecular weight kininogens using murine monoclonal antibodies.

Thirty-four monoclonal antibodies directed against human high molecular weight (HMW) and low molecular weight (LMW) kininogens and their derivatives were obtained, and the specificities of the antibodies were assayed by enzyme-linked immunosorbent assay (ELISA). By use of HMW kininogen, kinin-free HMW kininogen, kinin-free and fragment 1.2 (fr 1.2) free HMW kininogen, fr 1.2-light chain of HMW kininogen, LMW kininogen, kinin-free LMW kininogen, heavy chain of LMW kininogen, and light chain of LMW kininogen, the monoclonal antibodies were characterized and classified into four groups: (A) 20 monoclonal antibodies reacting with only the heavy chain, a common region of HMW and LMW kininogens; each of these monoclonal antibodies possessed the specificity to domain 1 (2 monoclonal antibodies), domain 2 (2 monoclonal antibodies), domain 3 (7 monoclonal antibodies), and both domains 2 and 3 (7 monoclonal antibodies) of the heavy chain; (B) 7 monoclonal antibodies reacting with fr 1.2, a unique histidine-rich region; (C) 5 monoclonal antibodies reacting with the light chain of HMW kininogen; (D) 2 monoclonal antibodies reacting with the light chain of LMW kininogen. Two monoclonal antibodies in the first group (group A), designated HKG H7 and H12, effectively suppressed the thiol proteinase inhibitor activity of HMW kininogen to papain and calpains and of LMW kininogen to papain, but the others did not affect it. Further, all the monoclonal antibodies which recognized the fr 1.2 or light chain of HMW kininogen (groups B and C) suppressed the clotting activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed2000

Whale high-molecular-weight and low-molecular-weight kininogens.

The expression of high-molecular-weight and low-molecular-weight kininogen mRNAs in the whale liver was examined by reverse transcription-polymerase chain reaction. The nucleotide sequences of the high-molecular-weight and low-molecular-weight kininogen cDNAs were analyzed and deduced to the amino acid sequences. The high-molecular-weight kininogen composed of 609 amino acid residues with 18 signal peptides possessed the consensus sequences of the cysteine protease inhibitor domains I and II, the bradykinin domain, the histidine-rich region, and the prekallikrein-binding region. Except for the histidine-rich region, the overall homologies with bovine, human, and rat high-molecular-weight kininogens were 81%, 76%, and 62%, respectively. The low-molecular-weight kininogen is composed of 408 amino acid residues. The nucleotide sequence down to C(1200) as well as the amino acid sequence till Ile(382) is identical to that of the high-molecular-weight kininogen. The remaining low-molecular-weight kininogen-specific carboxy-terminal portion possessed an amino acid sequence similar to that of the land mammals. The overall homologies with bovine, human, and rat low-molecular-weight kininogens were 82%, 79%, and 64%, respectively. The amino acid sequences of both whale high-molecular-weight and low-molecular-weight kininogens are most similar to those of the bovine among the land mammals analyzed so far. An incubation of dolphin/whale plasma with human plasma kallikrein, or with bovine trypsin, in the presence of carboxypeptidase inhibitors generated bradykinin antigen as well as the spasmogenic activity to the estrous rat uterus. The amount of bradykinin released by the latter enzyme was almost double of the former, indicating that the dolphin/whale plasma contained similar concentrations of low-molecular-weight and high-molecular-weight kininogens.

Amino Acid Sequence↗
PubMed1987

Interaction of human calpains I and II with high molecular weight and low molecular weight kininogens and their heavy chain: mechanism of interaction and the role of divalent cations.

Calpain I prepared from human erythrocytes was half-maximally and maximally activated at 23 and 35 microM calcium ion, and two preparations of calpain II from human liver and kidney were half-maximally activated at 340 and 220 microM calcium ion and maximally activated at 900 microM calcium ion, respectively. High molecular weight (HMW) and low molecular weight (LMW) kininogens isolated from human plasma and the heavy chain prepared from these proteins inhibited calpain I as well as calpain II. The molar ratios of calpains to HMW kininogen to give complete inhibition of calpains were 1.4 for calpain I and 2.0 for calpain II, and those of calpains to heavy chain were 0.40-0.66 for calpain I and 0.85 for calpain II. LMW kininogen did not completely inhibit the calpains even with an excess amount of kininogen. The apparent binding ratio of calpain to HMW kininogen estimated from the disc gel electrophoretic analysis, however, was found to be 2:1, whereas those of calpain to LMW kininogen and of calpain to heavy chain were found to be 1:1. Calpains and kininogens failed to form complexes in the absence of calcium ion. In the presence of calcium ion, however, they formed the complexes, which were dissociable by the addition of ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid. The minimum concentrations of calcium ion required to induce complex formation between calpain I and kininogens and calpain II and kininogens were 70 and 100 microM, respectively. Some other divalent cations such as Mn2+, Sr2+, and Ba2+ were also able to induce the complex formation between calpains and kininogens.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium↗
PubMed1997

Molecular weight measurements of low molecular weight heparins by gel permeation chromatography.

The molecular weight profiles of low molecular weight heparin samples have been measured by high-performance gel permeation chromatography using as calibrant the heparinase-degraded material (90/686) now established as the 1st International Reference Preparation (IRP) Low Molecular Weight Heparin for Molecular Weight Calibration Use of the calibrant as a broad molecular weight standard is described and a calibration table provided based on data collected over several years in one laboratory. In order to confirm the assignment of degree of polymerisation to resolved oligosaccharide peaks in the calibrant, molecular weights of oligosaccharides fractionated from the 1st IRP were independently determined by fast atom bombardment mass spectrometry (FAB MS). The molecular weight distributions of commercial low molecular weight heparins have been characterized. Measurements of molecular weight parameters of heparin molecular weight standards from several sources provide comparisons between the molecular weight scales of this and other studies.

Calibration↗
PubMed1985

Self-association mode of a flavoenzyme D-amino acid oxidase from hog kidney. I. Analysis of apparent weight-average molecular weight data for the apoenzyme in terms of models.

The self-association of D-amino acid oxidase apoenzyme in 0.1 M sodium pyrophosphate, pH 8.3, at 25 degrees C was studied by low-angle laser light scattering. The concentration (c) dependence of the apparent weight-average molecular weight (Mwapp) was determined over a wide concentration range of 0.04 to 6.1 mg/ml. The extrapolated Mwapp value, to zero enzyme concentration, corresponded to the Mr value of the monomer. The self-association mode of the apoenzyme was systematically explored with nonlinear least-squares analysis of the Mwapp versus c data. The simplest model that fitted the data well was a model of isodesmic indefinite self-association of the monomer with the isodesmic association constant of 0.467 +/- 0.034 liter/g. The monomer-dimer model proposed previously, but only in a low enzyme concentration range of less than 0.9 mg/ml at 5-20 degrees C (Henn, S. W., and Ackers, G. K. (1969) Biochemistry 8, 3829-3838), did not fit the Mwapp versus c data either in the limited low concentration range or in the whole concentration range examined at 25 degrees C. To test the validity of the chosen model, the observed sedimentation boundary profiles were compared with the idealized boundary profiles calculated for the better-fit models. The profile calculated with the model of the isodesmic indefinite self-association mechanism was qualitatively consistent with the observed ones. The utility of the nonlinear least-squares procedure for analyzing self-associating systems was demonstrated.

Animals↗
PubMed1989

Gas-phase sequencing after electroblotting on polyvinylidene difluoride membranes assigns correct molecular weights to myoglobin molecular weight markers.

Commercially available polypeptide marker kits containing peptides generated by cyanogen bromide cleavage of either horse heart myoglobin or sperm whale myoglobin have been investigated by sodium dodecyl sulfate - polyacrylamide gel electrophoresis (SDS-PAGE), followed by electroblotting on polyvinylidene difluoride membranes, and gas-phase sequencing. It could be shown that the molecular weights assigned to the SDS-PAGE bands by the companies are incorrect. Arranged in descending order, the marker kits are composed of the following polypeptide fragments from myoglobin: positions 1-153, 1-131, 56-153, 56-131, 1-55, and 132-153. A polypeptide comprising residues 1-14 was not found. According to these results the log Mr versus Rf plot used for calibration must be revised. For the separation of low molecular weight polypeptides and peptides a new gel system based on the theory of multiphasic zone electrophoresis combined with a modified Coomassie staining procedure is reported.

Amino Acid Sequence↗