scholarly journals Physical-chemical properties of C-phycocyanin isolated from an acido-thermophilic eukaryote, Cyanidium caldarium

1975 ◽  
Vol 147 (1) ◽  
pp. 63-70 ◽  
Author(s):  
O H Kao ◽  
M R Edwards ◽  
D S Berns
Keyword(s):  
Absorption Spectrum ◽  
High Temperature ◽  
Amino Acid ◽  
Ph Dependence ◽  
Chemical Properties ◽  
Sedimentation Velocity ◽  
Subunit Structure ◽  
Cyanidium Caldarium ◽  
Eukaryotic Alga ◽  
Physical Chemical

C-Phycocyanin from an acido-thermophilic eukaryotic alga, Cyanidium caldarium, was characterized with respect to subunit structure, absorption spectrum and fluorescence properties and was found to be similar to C-phycocyanins from mesophilic sources. The pH-dependence of fluorescence polarization and the changes in sedimentation velocity as a function of pH, concentration and temperature indicate the presence of extremely large amounts of unusually stable 19S aggregates. It was not possible to disaggregate this phycocyanin completely to monomer under normal conditions. The amino acid composition is similar to that of phycocyanins from other thermophilic and halophilic sources. The isoelectric point of this C-phycocyanin was 5.11, an unusually high value. The properties of this C-phycocyanin suggest an increase in protein stability as its mode of adaptation to the environmental stress of high temperature.

scholarly journals A study of the subunit structure and the thiol reactivity of bovine liver uridine diphosphate glucose dehydrogenase

1972 ◽  
Vol 129 (4) ◽  
pp. 821-830 ◽  
Author(s):  
P. A. Gainey ◽  
T. C. Pestell ◽  
C. F. Phelps
Keyword(s):  
Amino Acid ◽  
Amino Acid Analysis ◽  
Peptide Mapping ◽  
Ph Dependence ◽  
Glucose Dehydrogenase ◽  
Group Analysis ◽  
Subunit Structure ◽  
Uridine Diphosphate ◽  
Thiol Groups ◽  
Thiol Reactivity

1. The amino acid analysis of UDP-glucose dehydrogenase is reported. 2. N-Terminal-group analysis indicates only one type of N-terminal amino acid, methionine, to be present. 3. Peptide ‘mapping’ in conjunction with the amino acid analysis indicates that the subunits of the enzyme are similar if not identical. 4. The various kinetic classes of thiol group were investigated by reaction with 5,5′-dithiobis-(2-nitrobenzoate). 5. NAD+, UDP-glucose and UDP-xylose protect the two rapidly reacting thiol groups of the hexameric enzyme. 6. Inactivation of the enzyme with 5,5′-dithiobis-(2-nitrobenzoate) indicates the involvement of six thiol groups in the maintenance of enzymic activity. 7. The pH-dependence of UDP-xylose inhibition of the enzyme was investigated. 8. The group involved in the binding of UDP-xylose to the protein has a heat of ionization of about 33kJ/mol and a pK of 8.4–8.6. 9. It is suggested that UDP-xylose has a cooperative homotropic effect on the enzyme.

scholarly journals Physical-Chemical Properties of L-asparaginase Mutants From Rhodospirillum Rubrum which Showed Antitelomerase Activity

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
M.V. Pokrovskaya ◽  
S.S. Aleksandrova ◽  
A.V. Veselovsky ◽  
D.D. Zdanov ◽  
V.S. Pokrovsky ◽  
...  
Keyword(s):  
Amino Acid ◽  
Rhodospirillum Rubrum ◽  
Chemical Properties ◽  
Telomerase Activity ◽  
Kinetic Properties ◽  
Ph Optimum ◽  
Physical Chemical ◽  
Asparaginase Activity ◽  
Terminal Amino ◽  
Mutant Forms

Rru_A3730 protein is a bacterial Rhodospirillum rubrum L-asparaginase (RrA), which is known by its anticancer activity. RrA variants with point amino acid substitutions in the region of 150 amino acids residues: RrA17N, K149E, RrAE149R, V150P, F151T, RrА17N, E149R, V150P, RrAE149R, V150P, showed antiproliferative properties, and also by their ability to suppress telomerase activity. This work is devoted to comparison of physical-chemical and catalytic properties of these mutant forms of RrA. It is shown that pH optimum is in the alkaline zone (8.5 – 9.3); L-glutaminase and D-asparaginase activity is respectively not more than 0.1% and 1.6% of L-asparaginase for all studied variants of RrA. The presence of the N17-terminal amino acid sequence MASMTGGQMGRGSSRQ of the capsid protein of bacteriophage T7 in the RrA structure leads to an increase in the thermal stability of mutant RrA analogues (from 50°C to 56°C) and their resistance to denaturation in the presence of 3 – 4 M urea. It is of Metal ions exhibit multidirectional effects on L-asparaginase activity of RrA. K+, Ca2+, Zn2+, Cs+, Co2+ in significantly affect the activity of L-asparaginase, while Mn2+, Cu2+, Fe3+ ions inhibit it. There was no correlation between antitelomerase (antiproliferative) activity and kinetic properties of mutant forms of L-asparaginase RrA.

scholarly journals Self-association of unconjugated bilirubin-IX α in aqueous solution at pH 10.0 and physical-chemical interactions with bile salt monomers and micelles

1979 ◽  
Vol 179 (3) ◽  
pp. 675-689 ◽  
Author(s):  
M C Carey ◽  
A P Koretsky
Keyword(s):  
Aqueous Solution ◽  
Absorption Spectrum ◽  
Bile Salt ◽  
Bile Salts ◽  
Sodium Dodecyl ◽  
Chemical Properties ◽  
Critical Micellar Concentration ◽  
Solvent Mixtures ◽  
Physical Chemical ◽  
Self Association

Spectrophotometric measurements of bilirubin-IX alpha in water and in aqueous/organic solvent mixtures at pH 10.0 as a function of bilirubin-IX alpha concentration (approx. 0.6–400 microM) are consistent with the formation of dimers (KD - 1.5 microM) in dilute (less than 10 microM) aqueous solution and further self-aggregation to multimers at higher concentrations. Added urea (to 10M) and increases in temperature (to 62 degrees C) obliterate the dimer-multimer transition at 10 microM, but added NaCl (to 0.30 M) promotes strong aggregation of dimers over a narrow concentration range, suggesting a ‘micellization’ phenomenon. Concentrations of dioxan or ethanol greater than 60% (v/v) in water were required to obtain the absorption spectrum of bilirubin-IX alpha monomers, suggesting that both hydrophobic and electrostatic (pi-orbital) interactions are involved in stabilizing the dimeric state in water. Micellar concentrations of sodium dodecyl sulphate induced spectrophotometric shifts in the dimer absorption spectrum of bilirubin-IX alpha consistent with progressive partitioning of bilirubin-IX alpha monomers into a relatively non-polar region of the micelles and allowed a deduction of the apparent critical micellar concentration that closely approximated the literature values. The pattern of bilirubin IX alpha association with bile salts is complex, since the absorption spectrum shifts hypsochromically below and bathochromically above the critical micellar concentration of the bile salts. Consistent with these observations, bilirubin IX alpha appears to bind to the polar face of bile salt monomers and to the polar perimeter of small bile salt micelles. At higher bile salt concentrations some-bilirubin-IX alpha monomers partition into the hydrophobic interior of the bile salt micelles. Our results suggest that under physiological conditions the natural conjugates of bilirubin-IX alpha may exhibit similar physical chemical properties in bile, in that dimers, highly aggregated multimers and bile salt-associated monomers may co-exist.

scholarly journals Quality of UHT whole milk marketed in Pernambuco, Brazil

2021 ◽  
Vol 15 (3) ◽  
pp. 282-288
Author(s):  
Amanda Thaís Ferreira Silva ◽  
Diana Guiomar Ferreira Sena ◽  
Daniel Dias Silva ◽  
Thamyris Gracinda P. Khoury Souza ◽  
Elizabeth Sampaio Medeiros ◽  
...  
Keyword(s):  
High Temperature ◽  
Microbiological Quality ◽  
Chemical Properties ◽  
Quality Standards ◽  
Chemical Analyses ◽  
Physical Chemical ◽  
Whole Milk ◽  
Processing Plants ◽  
Further Development

The objective of this study was to evaluate the physical-chemical properties and microbiological quality of Ultra-high temperature (UHT) whole milk marketed in Pernambuco state, Brazil. In total, 390 samples of UHT whole milk were purchased from commercial establishments located in the mesoregions of Pernambuco, and transported to the Laboratory of Meat and Milk Inspection at the Federal Rural University of Pernambuco. The physical-chemical analyses and the microbiological evaluations were carried out in order to meet specific legislative mandates. All 13 brands tested met the determined physical-chemical standards. However, it was found that 105 (26.9%) samples did not meet microbiological standards. It is important to highlight the need for further development of integrated actions involving the inspection bodies and the processing plants, in order to adjust the product to the quality standards established in the legislation, respecting the rights and health of consumers.

Chlorinated Organics in Nearshore Waters and Tributaries of the St. Clair River

1986 ◽  
Vol 21 (3) ◽  
pp. 344-350 ◽  
Author(s):  
Barry G. Oliver ◽  
Klaus L.E. Kaiser
Keyword(s):  
United States ◽  
Suspended Sediment ◽  
Waste Disposal ◽  
Large Volume ◽  
Water Samples ◽  
Chemical Properties ◽  
Low Level ◽  
Chemical Company ◽  
Physical Chemical ◽  
The Individual

Abstract The concent rat ions of hexachloroethane (HCE), hexachlorobutadiene (HCBD), pentachlorobenzene (QCB), hexachlorobenzene (HCB) and octachlorostyrene (OCS) in large volume water samples show that the major sources of these chemicals to the St. Clair River are Dow Chemical Company effluents and, to a lesser degree, Sarnia’s Township ditch which drains one of Dow’s waste disposal sites. Tributaries entering the river on both sides of the Canada/United States border contain measurable concentrations of these chemicals indicating low level contamination throughout the area. The degree of water/suspended sediment partitioning of the chemicals (Kp) was studied. Kp values for the individual chemicals changed in a manner consistent with changes in their physical-chemical properties.

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