Accessibility of Tyrosine Residues in Cytochrome P-450scc (CYP11A1)

1998 ◽  
Vol 63 (10) ◽  
pp. 1678-1682
Author(s):  
Pavel Anzenbacher ◽  
Jiří Hudeček ◽  
Reinhard Lange ◽  
Frédéric Bancel
Keyword(s):  
Absorption Spectra ◽  
Conformational Equilibrium ◽  
Ultraviolet Region ◽  
Conformational States ◽  
Compact Structure ◽  
Tyrosine Residues ◽  
Temperature Range ◽  
Ph Values ◽  
Derivatives Of

Cytochrome P-450scc (CYP11A1) is known to exist in various conformational states. To study the accessibility of tyrosine residues to the solvent, second and fourth derivatives of cytochrome absorption spectra in the ultraviolet region were used. The measurements were carried out in the temperature range -10 to 40 °C and at two pH values (6.8 and 7.4). Our results indicate that the tyrosine residues of this enzyme are less accessible at higher temperatures as well as at higher pH, that is at conditions where the conformational equilibrium shifts to low-spin Fe(III) form(s). In other words, a more compact structure is attributable to the low-spin Fe(III) form(s) of P-450scc.

Derivatives of isatin in aqueous solution. I. Kinetics of ring opening of Isatin-5-sulfonate

1981 ◽  
Vol 34 (2) ◽  
pp. 365 ◽  
Author(s):  
H Stunzi
Keyword(s):  
Ring Opening ◽  
Rate Of Change ◽  
Spectroscopic Methods ◽  
Ph Values ◽  
Buffer Region ◽  
Pka Value ◽  
Back Titration ◽  
Kinetics Of ◽  
Derivatives Of ◽  
Sulfonate Anion

The reactions of isatin-5-sulfonate anion (si-) which cause a hysteresis in pH titrations were studied by pH-metric and n.m.r, spectroscopic methods. Rapid alkalimetric titrations [I 0.15 M (KNO3),37�] gave the pKa value corresponding to the addition of OH- to si- [pKa(ring) 9.55]. The slow ring opening to the sulfonatoisatate dianion (sia2-) led to a drift of the pH values towards an equilibrium buffer region. Its pKa, value [pKa(eq) 3.44] corresponds to the reaction si-+H2O ↔ sia 2-+H+ Rapid back-titration gave the pKa value of the ring-opened species Hsia- [pKa(open) c. 1.3]. The rate law for the ring opening d[sia]/dt=k2 [siOH](OH)+k1*[si] was obtained from the rate of change of pH. N-Methylisatin-5-sulfonate behaves analogously.

STUDY OF ABSORPTION SPECTRA OF THE COMPLEXES OF BOVINE SERUM ALBUMIN WITH HOECHST 33258 AND METHYLENE BLUE

2021 ◽  
Vol 55 (2 (255)) ◽  
pp. 158-164
Author(s):  
Nara H. Petrosyan
Keyword(s):  
Methylene Blue ◽  
Serum Albumin ◽  
Absorption Spectra ◽  
Hoechst 33258 ◽  
Differential Absorption ◽  
Partial Loss ◽  
Groove Binding ◽  
Compact Structure ◽  
Binding Material ◽  
Molecular Compounds

The study on the interaction of DNA-specific low-molecular compounds – groove binding material Hoechst 33258 and intercalating ligand methylene blue (MB) with serum albumin has been carried out. The absorption and differential absorption spectra of complexes of the mentioned ligands with protein were obtained. Changes of the absorption and differential absorption spectra indicate the binding of two ligands with albumin. The obtained results indicate that at the interaction with both ligands, the conformational state of the protein alters, though these changes are not similar, since in the case of MB a compactization of the protein folding occurs, while in the case of Hoechst 33258, most apparently, an unfolding of the compact structure takes place as a result of partial loss of helicity of $\alpha$-structures.

Bacterial Spoilage of Citrus Products at pH Lower than 3.51

1976 ◽  
Vol 39 (12) ◽  
pp. 819-822 ◽  
Author(s):  
B. J. JUVEN
Keyword(s):  
Acetic Acid ◽  
Lactic Acid ◽  
Thermal Resistance ◽  
Tartaric Acid ◽  
Lactobacillus Brevis ◽  
Acid Inhibition ◽  
Temperature Range ◽  
Ph Values ◽  
Sugar Syrup ◽  
Z Value

A strain of Lactobacillus brevis, L-3, was isolated from a blown can of grapefruit segments in sugar syrup; it caused spoilage of citrus products having pH values lower than 3.5. When inoculated into orange (pH 3.38) and grapefruit (pH 2.99) juices, after 5 h at 30 C L-3 produced 15 and 22 μg diacetyl/ml, respectively, and off-flavor was detectable. L-3 grew in APT broth acidified to pH 3.0 with citric, hydrochloric, phosphoric, or tartaric acid. However, its growth was inhibited at pH 3.6 if the acidulant was lactic acid, while with acetic acid inhibition occurred at a pH between 3.7 and 4.0. The thermal resistance of L-3 in orange serum (pH 3.4) was studied in the temperature range of 52 to 60 C: a z value of 8.3 was obtained. A simple and reliable capillary technique for studying the thermal resistance of gas-producing organisms in liquid foods and media is presented.

scholarly journals Влияние концентрации примеси магния на электрические свойства кристаллов LiNbO-=SUB=-3-=/SUB=-

2021 ◽  
Vol 63 (10) ◽  
pp. 1566
Author(s):  
А.В. Яценко ◽  
С.В. Евдокимов ◽  
В.Ф. Шульгин ◽  
М.Н. Палатников ◽  
Н.В. Сидоров ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Absorption Spectra ◽  
Impurity Content ◽  
Threshold Value ◽  
Ir Absorption ◽  
Temperature Range ◽  
Polar Direction ◽  
Ir Absorption Spectra ◽  
Mg Content

Using the results of studying the electrical conductivity in the temperature range of ~ 295-460 K and the IR absorption spectra of a series of LiNbO3: Mg crystals, it is shown that as the Mg content in the sample increases, the mobility of H+ ions sharply decreases when moving along the polar direction. This effect is most clearly manifested in the samples of LiNbO3: Mg crystals with a high (above threshold value) impurity content.

Absorption spectra of volatile aromatic hydrocarbon films in the vacuum ultraviolet region

1982 ◽  
Vol 71 (1) ◽  
pp. 135-144 ◽  
Author(s):  
Shojun Hino ◽  
Tamás Veszprémi ◽  
Koichi Ohno ◽  
Hiroo Inokuchi ◽  
Kazuhiko Seki
Keyword(s):  
Aromatic Hydrocarbon ◽  
Absorption Spectra ◽  
Vacuum Ultraviolet ◽  
Ultraviolet Region ◽  
Hydrocarbon Films ◽  
Vacuum Ultraviolet Region
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