| 1. |
|
|
| 2. |
|
|
| 3. |
- Lipnizki, Frank, et al.
(författare)
-
Einsatz von Pervaporation-Bioreaktor-Hybridprozessen in der Biotechnologie
- 1998
-
Ingår i: Chemie-Ingenieur-Technik. - : Wiley. - 0009-286X .- 1522-2640. ; 70:12, s. 1587-1595
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Pervaporation is a membrane separation process with considerable innovative possibilities in the area of biotechnology. Above all, the combination of bioreactor and pervaporation has potential in the longer term as an alternative to conventional batch processes. This article considers the state of the art of pervaporation/bioreactor hybrid processes. The possible applications of such hybrid processes are discussed and compared with conventional processes. It becomes apparent that the use of pervaporation/bioreactor hybrid processes can avoid product inhibition and greatly enhance the productivity of biotechnological processes.
|
|
| 4. |
- Behravan, Gity, et al.
(författare)
-
Formation of a free radical of the sulfenylimine type in the mouse ribonucleotide reductase reaction with 2'-azido-2'-deoxycytidine 5'-diphosphate
- 1995
-
Ingår i: Biochimica et Biophysica Acta, Gene Structure and Expression. - : Elsevier BV. - 0167-4781 .- 1879-2634. ; 1264:3, s. 323-329
-
Tidskriftsartikel (refereegranskat)abstract
- Mouse and Escherichia coli ribonucleotide reductases (RR) both belong to the same class of RR, where the enzyme consists of two non-identical subunits, proteins R1 and R2. A transient free radical was observed by EPR spectroscopy in the mouse RR reaction with the suicidal inhibitor 2′-azido-2′-deoxycytidine 5′-diphosphate. The detailed hyperfine structure of the EPR spectrum of the transient radical is somewhat different for the mouse and previously studied E. coli enzymes. When the positive allosteric effector ATP was replaced by the negative effector dATP, no transient radical was observed, showing that ‘normal' binding of the inhibitor to the substrate binding site is required. Using the mouse protein R2 mutants W 103Y and D266A, where the mutations have been shown to specifically block long range electron transfer between the active site of the R1 protein to the iron/radical site in protein R2, no evidence of transient radical was found. Taken together, the data suggest that the radical is located at the active site in protein R1, and is probably of the sulfenylimine type
|
|
| 5. |
- Dunuwila, D.D., et al.
(författare)
-
ATR FTIR spectroscopy for in situ measurement of supersaturation
- 1997
-
Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 179:1-2, s. 185-193
-
Tidskriftsartikel (refereegranskat)abstract
- The current contribution establishes the technical feasibility of Attenuated Total Reflection (ATR) Fourier transform infrared (FTIR) spectroscopy for the in situ measurement of supersaturation in crystallization processes. The approach was inspired by recent advancements in ATR spectroscopy by way of various light transfer systems for remote sensing and by the increasing availability of ATR configurations well suited for remote, in situ measurements. The feasibility of the technique was investigated using a DIPPER-210® immersion probe manufactured by Axiom Analytical, Inc. Initial experiments conducted using aqueous maleic acid proved that ATR FTIR spectroscopy can be successfully employed to measure supersaturation, solubility and the metastable limit, in situ, with sufficient accuracy and precision.
|
|
| 6. |
|
|
| 7. |
- LeCaptain, D.J., et al.
(författare)
-
Applicability of second harmonic generation for in situ measurement of induction time of selected crystallization systems
- 1999
-
Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 203:4, s. 564-569
-
Tidskriftsartikel (refereegranskat)abstract
- The nonlinear optical technique of second harmonic generation (SHG) is introduced as a novel technique for monitoring particle formation in batch crystallizations. SHG is more sensitive and is less prone to interference than turbidometric methods. The studies presented show the applicability of SHG as a method for in situ measuring the induction time of a number of noncentrosymmetric crystal systems.
|
|
| 8. |
- Miranda, E.A., et al.
(författare)
-
Development of precipitant agents for precipitation of proteins based on hydrophobic interaction
- 1995
-
Ingår i: Brazilian journal of chemical engineering. - 0104-6632 .- 1678-4383. ; 12:1, s. 1-12
-
Tidskriftsartikel (refereegranskat)abstract
- Precipitation agents were developed to perform protein separation by precipitation based on hydrophobic interaction. They consisted of ligands, saturated linear chains of fatty acids, attached by esterification to a carrier molecule, methylcellulose. Precipitation of bovine serum albumin was achieved at 50 percent saturation of ammonium sulfate. The butyric acid derivative showed a higher efficiency in precipitating this protein than other derivatives tested. There is evidence that the interaction between the protein and the derivatives is hydrophobic.
|
|
| 9. |
- Pan, Borlan, et al.
(författare)
-
Time-resolved fluorescence and anisotropy of covalently coupled 1-pyrenebutyric acid for monitoring the crystallization conditions of lysozyme
- 1997
-
Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 171:1-2, s. 226-235
-
Tidskriftsartikel (refereegranskat)abstract
- Time-resolved fluorescence and anisotropy measurements of trace amounts of 1-pyrenebutyric acid labeled hen egg-white lysozyme (PBA-HEL) were used to characterize hen egg-white lysozyme (HEL) crystallization conditions. The effects of sodium chloride and protein concentrations on the fluorescence lifetimes and rotational correlation times of the labeled protein were examined. These results were compared with the effects of the salts ammonium acetate and ammonium sulfate. Addition of protein precipitants caused increases in the rotational correlation times which were attributed to a combination of steric, hydrodynamic, general electrostatic and specific ionic interactions. This decrease in the rotational mobility of HEL appears to be a necessary but not sufficient condition to allow the formation of specific interactions leading to crystallization. The results demonstrated that fluorescence measurements are effective in characterizing and monitoring protein crystallization processes prior to the appearance of macroscopic crystals.
|
|
| 10. |
- Rasimas, J. P., et al.
(författare)
-
A molecular lock-and-key approach to detecting solution phase self-assembly : a fluorescence and absorption study of carminic acid in aqueous glucose solutions
- 1996
-
Ingår i: Journal of Physical Chemistry. - : American Chemical Society (ACS). - 0022-3654 .- 1541-5740. ; 100:17, s. 7220-7229
-
Tidskriftsartikel (refereegranskat)abstract
- We introduce a novel approach to the study of complex ternary systems where a fluorescent chromophore contains a functionality that incorporates into precrystalline aggregates in concentrated solutions. We demonstrate the feasibility of this approach by using carminic acid, a fluorescent molecule possessing a pendant glycosyl moiety, in aqueous glucose solutions. We report the steady state absorption and emission response of carminic acid as well as its picosecond dynamical response. These data, taken collectively, show that saturated glucose solutions exhibit anomalous molecular scale organization and that the persistence time of this organization is significantly less than a nanosecond. Our results indicate that kinetic contributions to crystallization are expected to play an important, sometimes dominant, role in this technologically important process.
|
|
