The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Peroxynitrite (PN) can be formed under mainly pathophysiological conditions from nitric oxide (NO) and superoxide anion and may be responsible for oxidative modifications of biomolecules. Preparations of nitric oxide synthases from porcine cerebellum (nNOS), bovine aortic endothelium (eNOS) and cytokine-treated murine macrophages (iNOS) were inhibited by PN in their ability to transform arginine...
The kinetics of CO binding to cytochrome P450, as measured by the flash photolysis technique, is a powerful probe of P450 structure-function relationships. The kinetics are sensitive to P450 conformation and dynamics and are modulated by P450 interactions with substrates and other components of the microsomal membrane. Application of a difference method to kinetic data analysis distinguishes the...
In the present paper, the application of scanning tunneling microscopy in cytochrome P450s membrane topology is discussed. The method enables visualization of heme location in the lipid-bilayer-incorporated protein. It is supposed that the membrane-bound cytochrome P450 on the tunneling microscope substrate should behave as molecular diode . A model explaining the liposome and the proteoliposome...
In the active center of cytochrome P450cam, Thr-252 is one of the conserved amino acid residues in the cytochrome P450 superfamily and plays a key role in hydroxylation of camphor. T252A mutant, in which Thr-252 is replaced by alanine, consumed O 2 at a rate comparable to that of the wild-type enzyme, whereas the amount of exo-5-hydroxycamphor formed was less than 10% of that formed by the...
A single amino acid substitution is sufficient to alter substrate specificity of P450 enzymes. Mouse P450 2a5, for example, has its substrate specificity converted from coumarin 7- to testosterone 15α-hydroxylase activity by the substitution of Phe at position 209 to Leu. Furthermore, placing Asn at this position confers a novel corticosterone 15α-hydroxylase activity to this P450. Recent site-directed...
A peptide scanning (PEPSCAN) approach was used for antigenic mapping of two hepatic microsomal cytochromes P450 (rab1A2 and rab2B4) and the microbial cytochrome from Pseudomonas putida (P450 101 or P450cam). This approach includes simultaneous synthesis of pin-linked overlapping hexapeptides covering the whole sequences of three P450s and testing them by ELISA with corresponding polyclonal antisera...
A new method for monitoring the formation of the cytochrome P450 complexes with NADPH-cytochrome P450 reductase (NCPR) is introduced. The method is based on the quenching of fluorescence of NCPR labelled with 7-ethylamino-3-(4 -maleimidilphenyl)-4-methylcoumarin maleimide (CPM). In a monomerized soluble reconstituted system in the absence of phospholipid, cytochrome P450 2B4 and NCPR c ...
Although halogenated hydrocarbons are noted for low chemical reactivity, small amounts are toxic to humans. Cytochromes P450 have been implicated in transforming these compounds to more reactive species, under anaerobic conditions, through reduction at the heme. A significant amount of effort has been directed toward turning this catalytic ability to our advantage by engineering P450 variants than...
The understanding of structure-function relationship of enzymes requires detailed information of their three-dimensional structure. Protein structure determination by X-ray and NMR methods, the two most frequently used experimental procedures, are often difficult and time-consuming. Thus computer modeling of protein structures has become an increasingly active and attractive option for obtaining...
The cDNAs and genes for two isozymes of cytochrome P450nor of the fungus Cylindrocarpon tonkinense, P450nor1 and P450nor2, were cloned and sequenced. Their deduced amino acid sequences respectively showed 83 and 70% identity to that of P450nor of Fusarium oxysporum, and 69% identity to each other. The genes for P450nor1 and P450nor2 were termed, respectively, CYP 55A2 and CYP 55A3. The cDNA for...
There now are four known cytochrome P450 crystal structures. Two of these, P450cam and P450eryF, are substrate-bound while P450terp and the heme domain of P450BM-3 are substrate-free. Here we describe a preliminary analysis of the P450BM-3 heme domain complexed with the 16-carbon fatty acid substrate, palmitoleic acid. A comparison of the substrate-free and -bound structures shows that a large...
The kinetics of carbon monoxide binding to cytochrome P450 BM-3 in the presence and absence of substrate has been investigated using flash photolysis. The second order kinetics for CO association with the substrate-free form of the protein appear biphasic. Deconvolution into two exponentials yields fast and slow rate constants of 11.1 ± 0.6 10 6 M -1 ...
Putidaredoxin (Pdx) is a Fe 2 S 2 ferredoxin which acts as the physiological reductant of cytochrome P-450 cam (CYP101). A model for the solution structure of oxidized Pdx has been determined using NMR methods (Pochapsky et al (1994) Biochemistry 33, 6424-6432). 1 H- 15 N correlations and redox-dependent amide exchange rates have also been described...
The influence of ionic strength on the interactions between individually expressed functional domains of cytochrome P450BM-3 and the domains in the holoenzyme has been analyzed by spectrophotometric and fluorometric techniques. High ionic strength facilitated electron transfer from NADPH to the FMN moiety of the reductase domain (BMR) of P450BM-3 and did not affect the first electron transfer from...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.